METHOD FOR APPLYING A MEASUREMENT SCALE TO A SURFACE OF A GUIDE RAIL OF A LINEAR PROFILE RAIL GUIDE, MEASUREMENT SCALE FOR A LINEAR ENCODER, AND LINEAR ENCODER

Abstract

A method for applying a measurement scale to a guide rail surface of a linear profile rail guide, the guide rail having a first side surface and the measurement scale including at least one track extending linearly and longitudinally toward the guide rail, including several mirror regions arranged alternately one behind the other, and marking regions, uses a pulsed laser to generate a laser beam and introduces a microstructure in a first region corresponding to the at least one marking region of the first side surface. The laser generates the laser beam with a sequence of several light pulses that is directed at the first region so that the laser beam is moved two-dimensionally relative to the first region to irradiate different subregions of the first region one after the other by the light pulses. Each different irradiated subregion has an overlap with at least one other irradiated subregion.

Claims

1. A method for applying a measurement scale (15) to a surface of a guide rail (2) of a linear profile rail guide (1), wherein the guide rail (2) has a first side surface (2.1) and an opposite second side surface (2.2), wherein the measurement scale (15) comprises at least one track (SP1, SP2), which extends linearly in the longitudinal direction (X) of the guide rail (2), comprising several mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15), which are arranged one behind the other so as to alternate, and marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14), wherein each of the marking regions extends in a line-like manner transverse to the longitudinal direction (X) of the at least one track (SP1, SP2), and wherein the method has the following method steps: providing a pulsed laser for generating a laser beam; and providing at least one of the marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) by introducing a microstructure in a first region (B1), which corresponds to the at least one marking region, of the first side surface (2.1) of the guide rail (2), in that: the laser generates the laser beam with a sequence of several light pulses, and the laser beam is directed at the first region (B1, B2) of the first side surface (2.1) in such a way that only a subregion (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1) is irradiated by means of each individual light pulse of the generated sequence of several light pulses in such a way that the first side surface (2.1) in the subregion (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1), which is irradiated by means of the respective individual light pulse, is changed due to the irradiation by means of the respective individual light pulse in such a way that after the irradiation by means of the respective individual light pulse, the first side surface (2.1) has a spatial modulation of the first side surface (2.1), which extends over the subregion (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region (B1), which is irradiated by means of the respective individual light pulse, wherein the spatial extension (D) of the subregion of the first region (B1), which is irradiated by means of the respective individual light pulse, in the longitudinal direction (X) of the at least one track is smaller than the spatial extension (DBX) of the first region (B1) in the longitudinal direction (X) of the at least one track (SP1, SP2), and that the spatial extension (D) of the subregion irradiated by means of the respective individual light pulse transverse to the longitudinal direction (X) of the at least one track (SP1, SP2) is smaller than the spatial extension (DBY) of the first region (B1) transverse to the longitudinal direction (X) of the at least one track (SP1, SP2); the laser beam is moved relative to the guide rail (2), so that at least several of the light pulses of the generated sequence of several light pulses irradiate several different subregions (TB11, TB15, TB16, TB1n, TB21, TB25, TB26, TB2n) of the first region, which are arranged spatially distributed to one another, sequentially in time, wherein for each individual one of the several different irradiated subregions (TB15), at least two other ones of the several different irradiated subregions (TB16, TB25) are present, which are offset to the respective individual one of the several different irradiated subregions (TB15) in such a way that one of the at least two other ones of the several different irradiated subregions (TB25) is offset relative to the respective individual one of the several different irradiated subregions (TB15) in the longitudinal direction (X) of the at least one track (SP1, SP2) so that the one of the at least two other ones of the several different irradiated subregions (TB25) and the respective individual one of the several different irradiated subregions (TB15) have an overlap (UX), and that the other one of the at least two other ones of the several different irradiated subregions (TB16) is offset relative to the respective individual one of the several different irradiated subregions (TB15) transverse to the longitudinal direction (X) of the at least one track (SP1, SP2) so that the other one of the at least two other ones of the several different irradiated subregions (TB16) and the respective individual one of the several different irradiated subregions (TB15) have an overlap (UY), and wherein the several different irradiated subregions together form a region of the first side surface, which is congruent with the first region (B1).

2. The method according to claim 1, wherein the method further has the following method steps: prior to the introduction of the microstructure into the first side surface (2.1) of the guide rail (2) by means of the pulsed laser beam, at least the first side surface of the guide rail is subjected to a surface treatment in such a way that little material is in particular removed from the first side surface of the guide rail; and after the introduction of the microstructure into the first side surface of the guide rail by means of the laser beam, at least the first side surface of the guide rail is subjected to a surface cleaning.

3. The method according to claim 1, wherein the overlap (UX) between the respective individual one of the several different irradiated subregions (TB11, TB1n) and the at least one other one of the several different irradiated subregions (TB21, TB2n) in the longitudinal direction (X) of the at least one track (SP1, SP2) has a spatial extension (DUX), which is 20-50% of the spatial extension (D) of the subregion of the first region, which is irradiated by means of the respective individual light pulse, in the longitudinal direction (X) of the at least one track (SP1, SP2), and/or wherein the overlap (UY) between the respective individual one of the several different irradiated subregions (TB15) and the at least one other one of the several different irradiated subregions (TB16) transverse to the longitudinal direction (X) of the at least one track (SP1, SP2) has a spatial extension (DUY), which is 20-50% of the spatial extension (D) of the subregion of the first region, which is irradiated by means of the respective individual light pulse, transverse to the longitudinal direction (X) of the at least one track (SP1, SP2).

4. The method according to claim 1, wherein the laser is formed as short-pulse laser for generating pulsed laser light by means of light pulses with pulse durations of less than 15 nanoseconds or as ultra short-pulse laser for generating pulsed laser light by means of light pulses with pulse durations of less than 20 picoseconds; and/or wherein the pulse parameters of the laser and/or a laser focus are/is selected in such a way that a material roughening in the nanometer range is formed when introducing the microstructure into the first side surface (2.1) of the guide rail (2) without material removal or at least without significant material removal along the surface paths.

5. The method according to claim 1, wherein prior to the introduction of the microstructure into the first side surface (2.1) of the guide rail (2) by means of the pulsed laser beam, at least the first side surface of the guide rail is subjected to the surface treatment by means of polishing; and/or wherein prior to the introduction of the microstructure into the first side surface of the guide rail by means of the pulsed laser beam, at least the first side surface (2.1) of the guide rail (2) is subjected to the surface treatment in such a way that the first side surface (2.1) of the guide rail (2) has an average roughness value (Ra) of maximally 0.3 ?m, preferably an average roughness value (Ra) of maximally 0.1 ?m, and even more preferably an average roughness value (Ra) in a range of approximately 0.007 ?m to 0.1 ?m.

6. The method according to claim 1, wherein prior to the introduction of the microstructure into the first side surface (2.1) of the guide rail (2) by means of the pulsed laser beam, at least the first side surface of the guide rail is subjected to the surface treatment by means of polishing disks, by means of laser polishing and/or by means of electropolishing.

7. The method according to claim 1, wherein after the introduction of the microstructure into the first side surface (2.1) of the guide rail (2), the first side surface (2.1) of the guide rail (2) has, in one of the marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) of the measurement scale (15), an average roughness value (Ra), which is greater by more than a factor of 10 than the average roughness value of the side surface (2.1) in one of the mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) of the measurement scale (15).

8. The method according to claim 1, wherein after the introduction of the microstructure into the first side surface (2.1) of the guide rail (2) by means of the laser beam, the first side surface (2.1) of the guide rail (2) is subjected to a surface cleaning, wherein the surface cleaning is a laser treatment and/or a vibration cleaning or an application of the first side surface with ultrasound.

9. The method according to claim 1, wherein the laser beam has an essentially round beam bundle and is selected in such a way that the beam bundle on the first side surface of the guide rail has a diameter of 3.5 ?m bis 12 ?m, preferably 6 ?m to 9 ?m, and in particular approximately 8 ?m; and/or wherein the laser is operated with a pulse frequency of approximately 60 kHz.

10. A measurement scale (15) for a linear encoder (11), which linear encoder (11) comprises a guide rail (2) of a linear profile rail guide (1), wherein the guide rail (2) has a first side surface (2.1) and an opposite second side surface (2.2), wherein the measurement scale (15) comprises at least one track (SP1, SP2) extending linearly in the longitudinal direction (X) of the guide rail (2) comprising several mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) arranged one behind the other so as to alternate, and marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14), wherein each of the marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) extends linearly transverse to the longitudinal direction (X) of the at least one track (SP1, SP2) and is formed to absorb incident light and/or to reflect it diffusely, wherein the mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15), have an at least essentially smooth surface, which is formed to reflect incident light in a reflective manner, wherein the measurement scale (15) is applied to the first side surface (2.1) of the guide rail (2) according to the method according to claim 1.

11. The measurement scale (15) according to claim 10, wherein the guide rail (2) has at least one and preferably a plurality of blind holesstarting at the second side surface (2.2)preferably comprising an internal thread, and wherein the first side surface (2.1) of the guide rail (2) is in particular provided without holes.

12. The measurement scale (15) according to claim 10, wherein the at least one track (SP1) is formed as incremental track comprising a plurality of equidistantly arranged marking regions (M) or the at least one track (SP2) is formed as reference track with at least one marking region (M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) for encoding at least one reference position.

13. A linear encoder (11), which has the following: the measurement scale (15) according to claim 10; and at least one sensor device (20), which is formed to optically scan the at least one track (SP1, SP2) of the measurement scale (15), wherein the at least one sensor device (22) has a measuring head (21), which can be moved relative to the measuring scale (15): a light source (22) for emitting light (22.1) onto mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) and marking regions (M; M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14) of the measurement scale (15), and at least one arrangement of photo sensors (25.1, 25.2), which are formed to detect light (RL1, RL2) emitted by the light source (22) and reflected on mirror regions (S; S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15) of the measurement scale (15).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0063] In the drawings,

[0064] FIG. 1 schematically shows the mode of operation of a distance measuring system comprising a linear encoder, which works according to the principle of the bright field measurement, for measuring a distance covered in the longitudinal direction of a guide rail of a linear profile rail guide (illustrated in a cross section perpendicular to the longitudinal direction of the guide rail);

[0065] FIG. 2 schematically shows an exemplary embodiment of an arrangement of marking regions of a measurement scale applied to the surface of a guide rail of a profile rail guide for a linear encoder according to FIG. 1;

[0066] FIG. 3A shows a schematic illustration of a first marking region of the measurement scale according to FIG. 2 and of an arrangement of surface regions of the guide rail, which are to be irradiated by means of light pulses of a pulsed laser beam, in order to provide for a provision of the first marking region on the surface of the guide rail according to the invention;

[0067] FIG. 3B shows, analogously to FIG. 3A, a schematic illustration of a second marking region of the measurement scale according to FIG. 2 and of an arrangement of surface regions of the guide rail, which are to be irradiated by means of light pulses of a pulsed laser beam, in order to provide for a provision of the second marking region on the surface of the guide rail according to the invention;

[0068] FIG. 4 shows a top view through a microscope onto a measurement scale applied to a surface of a guide rail of a profile rail guide by means of the method according to the invention;

[0069] FIG. 5 schematically shows marking regions introduced in the side surface of a guide rail of a profile rail guide by means of the method according to the invention prior to a surface cleaning;

[0070] FIG. 6 schematically shows the marking regions according to FIG. 5 after performance of a surface cleaning; and

[0071] FIG. 7 shows a section from the illustration according to FIG. 4 for the magnified illustration of the surface of the guide rail in the region of a marking region with a magnification, which visualizes a roughening of the surface of the guide rail in the illustrated marking region.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0072] Unless mentioned otherwise, the same reference numerals are in each case used for the same elements in the figures.

[0073] The mode of operation of a distance measuring system 10 for measuring a distance covered in the longitudinal direction of a guide rail 2 of a linear profile rail guide 1 of a movable body 3 of the profile rail guide 1, which is guided on the guide rail 2, is illustrated in FIGS. 1 and 2. The movable body 3 of the profile rail guide 1 is thereby guided on the guide rail 2 in such a way that it can be moved linearly in the longitudinal direction of the guide rail 2. For this purpose, the movable body 3 of the profile rail guide 1 can be supported on the guide rail 2, for example via rolling bodies (not illustrated in the figures). It is assumed in the illustration according to FIGS. 1 and 2 that the X axis of a cartesian coordinate system illustrated in FIGS. 1 and 2 with three orthogonal axes X, Y or Z, respectively (X axis, Y axis or Z axis, respectively) extends in the longitudinal direction of the guide rail 2 and that the movable body 3 can thus be linearly moved in the direction of the X axis.

[0074] The distance measuring system 10 according to FIGS. 1 and 2 has an optical linear encoder 11, which works according to the principle of the bright field measurement and which provides for a measurement of a distance covered by the body 3 in the longitudinal direction of the guide rail 2. For this purpose, the linear encoder 11 comprises a measurement scale 15 extending in the longitudinal direction of the guide rail 2 comprising at least one track extending linearly in the longitudinal direction of the guide rail 2 comprising several mirror regions and marking regions arranged one behind the other so as to alternate, and at least one sensor device 20, which is formed to optically scan the at least one track of the measurement scale 15.

[0075] As suggested in FIG. 1, the measurement scale 15 is formed on a first side surface 2.1 of the guide rail 2. In order to provide for an optical scanning of the measurement scale 15, the sensor device 20 comprises a measuring head 21, which can be moved in the longitudinal direction of the guide rail 2 and which is fastened to the movable body 3 in such a way that the measuring head 21 is arranged so as to be located opposite the side surface 2.1 of the guide rail 2, which is provided with the measurement scale 15, and is moved together with the movable body 3 in response to a movement of the movable body 3 in the longitudinal direction of the guide rail 2.

[0076] As suggested in FIGS. 1 and 2, the measurement scale 15 comprises two different tracks, which are arranged on the first side surface 2.1 and which extend parallel to one another in the longitudinal direction of the guide rail 2, comprising several mirror regions and marking regions, which are arranged one behind the other so as to alternate: a first track SP1, which is formed as incremental track with a plurality of equidistantly arranged marking regions, and a second track SP2, which is formed as reference track and has at least one marking region for encoding at least one reference position, or which can alternatively also have several marking regions arranged one behind the other in the longitudinal direction of the guide rail 2 for encoding several different reference positions.

[0077] As suggested in FIG. 2, each of the marking regions of the first track SP1 and of the second track SP2 of the measurement scale 15 in each case extends on the first side surface 2.1 of the guide rail in a line-like manner in the direction of the Y axis illustrated in FIGS. 1 and 2, i.e. transverse to the longitudinal direction of the measurement scale 15 or transverse to the longitudinal direction of the guide rail 2, respectively.

[0078] As suggested in FIG. 2, the first track SP1 (incremental track) comprises a plurality of marking regions M, which are identical with respect to their geometric shape and with respect to their spatial extension in the direction of the X axis and with respect to their spatial extension in the direction of the Y axis. A mirror region S is in each case formed between two adjacent marking regions M, which are arranged directly one behind the other in the direction of the X axis, wherein all mirror regions S of the first track SP1 are identical with respect to their spatial extension in the direction of the X axis and with respect to their spatial extension in the direction of the Y axis.

[0079] As furthermore suggested in FIG. 2, the second track SP2 (reference track) in the present example comprises several (here, for example, a total of fourteen) marking regions M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 or M14, respectively, which are arranged one behind the other in a row in the longitudinal direction of the guide rail 2.

[0080] In the case of the second track SP2, a mirror region is in each case also formed between two adjacent marking regions, which are arranged directly one behind the other in the direction of the X axis, so that the above-mentioned marking regions M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 or M14, respectively, are arranged one behind the other in a row so as to alternate with mirror regions S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 or S15, respectively. The marking regions M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2, however, are not all identical to one another with respect to their spatial extension in the direction of the X axis. The mirror regions S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 are likewise not all identical to one another with respect to their spatial extension in the direction of the X axis. In this way, the different marking regions and mirror regions of the second track SP2 provide for an encoding of several different reference positions, which in each case unambiguously define several different absolute positions.

[0081] The measuring head 21 has a light source 22 (for example an LED), by means of which light in the form of a light beam 22.1 is emitted, which is directed essentially perpendicular at the side surface 2.1 of the guide rail 2, so that a portion of the light emitted by the light source 22 impinges on the first track SP1 of the measurement scale 15, and another portion of the light 22.1 emitted by the light source 22 impinges on the second track SP2 of the measurement scale 15. The mode of operation of the linear encoder 11 requires a regular (mirror-like) reflection of the light 22.1 emitted by the light source 22 on the side surface 2.1 of the guide rail 2, wherein each incident beam is to be reflected at the same angle to the surface normal, if possible.

[0082] As suggested in FIG. 1, that portion of the light 22.1 emitted by the light source 22, which impinges on the first track SP1 of the measurement scale 15, is reflected on the first track SP1; the light reflected on the first track SP1 of the measurement scale 15 is represented in FIG. 1 by means of light beams, which are identified with RL1. That portion of the light 22.1 emitted by the light source 22, which impinges on the second track SP2 of the measurement scale 15, is accordingly reflected on the second track SP2; the light reflected on the first track SP1 of the measurement scale 15 is represented in FIG. 1 by means of light beams, which are identified with RL2.

[0083] As furthermore suggested in FIG. 1, the measuring head 21 comprises an electronic light sensor chip 25, which is formed to detect the light RL1 reflected on the first track SP1 and the light RL2 reflected on the second track SP2, and to analyze the spatial distribution of the intensity of the reflected light RL1 and the spatial distribution of the intensity of the reflected light RL2.

[0084] For this purpose, the light sensor chip 25 comprises a first arrangement 25.1 of a plurality of photo sensors for detecting the light RL1 reflected on the first track SP1 of the measurement scale 15, and a second arrangement 25.2 of a plurality of photo sensors for detecting the light RL2 reflected on the second track SP2 of the measurement scale 15, and moreover further electronic elements (not illustrated in the figures), which are formed to evaluate corresponding output signals of the first arrangement 25.1 of photo sensors and/or output signals of the second arrangement 25.2 of photo sensors.

[0085] According to the invention, the measurement scale 15 is designed in such a way that the individual marking regions, i.e. the marking regions M of the first track SP1 and the marking regions M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2, essentially absorb the light 22.1 emitted by the light source 22 and impinging on the respective marking regions, and do not reflect it in the direction of the first arrangement 25.1 of photo sensors and/or in the direction of the second arrangement 25.2 of photo sensors. In this case, the light RL1 reflected on the first track SP1 of the measurement scale 15 consists essentially of light, which has been reflected on the mirror regions S of the first track SP1. The light RL2 reflected on the second track SP2 of the measurement scale 15 accordingly consists essentially of light, which has been reflected on the mirror regions S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2.

[0086] Under the above-mentioned circumstances, the spatial distribution of the intensity of the light RL1 reflected on the first track SP1 of the measurement scale 15 has a spatial variation in the longitudinal direction of the guide rail 2, which corresponds to the spatial arrangement of the mirror regions S of the first track SP1 in the longitudinal direction of the guide rail 2. The spatial distribution of the intensity of the light RL2 reflected on the second track SP2 of the measurement scale 15 accordingly has a spatial variation in the longitudinal direction of the guide rail 2, which corresponds to the spatial arrangement of the mirror regions S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2 in the longitudinal direction of the guide rail 2.

[0087] The first arrangement 25.1 of photo sensors comprises a plurality of photo sensors (not illustrated in FIG. 1), which are arranged one behind the other in a row in the longitudinal direction of the guide rail 2. The second arrangement 25.2 of photo sensors accordingly comprises a plurality of photo sensors (not illustrated in FIG. 1), which are arranged one behind the other in a row in the longitudinal direction of the guide rail 2.

[0088] If the movable body 3 is moved in the longitudinal direction of the guide rail 2, the arrangement 25.1 of photo sensors and the arrangement 25.2 of photo sensors of the measuring head 21 are then also moved in the longitudinal direction of the first track SP1 or of the second track SP2, respectively, of the measurement scale 15. In this case, the intensity of the light RL1 reflected on the first track SP1, which is detected by the individual photo sensors of the first arrangement 25.1 of photo sensors, in each case shows a variation as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2, in response to the movement of the movable body 3 in the longitudinal direction of the guide rail 2.

[0089] Due to the fact that the first track SP1 is formed as incremental track and the marking regions M of the first track SP1 are in each case arranged equidistantly one behind the other in the longitudinal direction of the guide rail 2, the intensity of the light RL1 reflected on the first track SP1, which is detected by the individual photo sensors of the first arrangement 25.1 of photo sensors, in each case shows a periodic variation as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2 in response to the movement of the movable body 3 in the longitudinal direction of the guide rail 2. The individual photo sensors of the first arrangement 25.1 of photo sensors accordingly in each case generate output signals, which vary periodically as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2 in response to a movement of the movable body 3 in the longitudinal direction of the guide rail 2.

[0090] It is generally possible to form the photo sensors of the first arrangement 25.1 of photo sensors in such a way that the individual photo sensors of the first arrangement 25.1 of photo sensors in each case generate output signals, the periodic variation of which as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2 corresponds to the course of a mathematical sine function or cosine function, respectively, in response to a movement of the movable body 3 in the longitudinal direction of the guide rail 2. An evaluation of the output signals of the photo sensors of the first arrangement 25.1 of photo sensors accordingly provides for a determination of a distance covered by the movable body 3 in response to a movement in the longitudinal direction of the guide rail 2.

[0091] As mentioned, the second track SP2 is formed as reference track, wherein the marking regions M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13 and M14 of the second track SP2 are not all identical to one another with respect to their spatial extension in the direction of the X axis, and the mirror regions S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 and S15 of the second track SP2 are likewise not all identical to one another with respect to their spatial extension in the direction of the X axis.

[0092] In this case, the intensity of the light RL2 reflected on the second track SP2, which is detected by the individual photo sensors of the second arrangement 25.2 of photo sensors, in each case shows a variation as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2, in response to the movement of the movable body 3 in the longitudinal direction of the guide rail 2, wherein this variation, however, does not have a periodic course as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2.

[0093] The individual photo sensors of the second arrangement 25.2 of photo sensors accordingly in each case generate output signals, which do not vary periodically as a function of the position of the movable body 3 with respect to the longitudinal direction of the guide rail 2 in response to a movement of the movable body 3 in the longitudinal direction of the guide rail 2. An evaluation of the output signals of the photo sensors of the second arrangement 25.2 of photo sensors accordingly provides for a determination of an absolute position of the movable body 3 with respect to the respective positions of the marking regions and mirror regions of the second track SP2 of the measurement scale 15.

[0094] Steel, in particular stainless steel, is generally used as material for guide rails of a linear profile rail guide. Surfaces of guide rails of this type, which are ground according to standard (i.e. unpolished), generally have a profile, which can deviate from a flat area in such a way that surfaces of this type effect a rather diffuse reflection of light.

[0095] If the light 22.1 emitted by the light source 22 were to be reflected diffusely on the respective mirror regions of the measurement scale 15, this could impact the measuring accuracy of the distance measuring system 10.

[0096] With regard to a realization of a measurement scale 15 on a first side surface of a guide rail 2 according to FIGS. 1 and 2, it is thus expedient that prior to the application of the measurement scale 15 to the side surface 2.1 of the guide rail 2 by means of the method according to the invention, the side surface 2.1 is initially subjected to a surface treatment in such a way that material is in particular removed slightly from the first side surface 2.1 of the guide rail 2, in order to reduce a roughness, which is originally present, of the side surface 2.1 and to accordingly form the side surface 2.1 to be as smooth or flat as possible, respectively.

[0097] For the surface treatment of the profile rail guide, the surface of the guide rail 2 is preferably polished in the region of the side surface 2.1. The polishing can take place in a variety of ways, but in particular by means of a pre-polishing by means of a ceramic grinding disk with a very fine grain size (400 or finer) and subsequent polishing by means of a polishing disk bound on the basis of rubber or synthetic resin. Alternative manufacturing types for polishing by means of polishing disk are laser polishing or electropolishing or polishing by means of polishing brushes.

[0098] After a surface treatment of this type of the side surface 2.1, the individual marking regions of the measurement scale 15 are subsequently applied to the first side surface 2.1 of the guide rail 2 with the help of a pulsed laser. Examples for the application of the individual marking regions of the measurement scale 15 according to the method according to the invention will be described below, for example with reference to FIGS. 3A and 3B.

[0099] FIG. 3A shows (in a top view onto the side surface 2.1) a first region B1 of the side surface 2.1, in which the side surface 2.1 is to be treated with the help of a pulsed laser, in order to form a microstructure, which represents one of the marking regions of the first track SP1 or of the second track SP2 of the measurement scale 15, in the first region B1.

[0100] Due to the fact that the respective marking regions of the first track SP1 or of the second track SP2 of the measurement scale 15 in each case extends in a line-like manner transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis according to FIGS. 1 and 2), it is assumed in the example according to FIG. 3A that the first region B1 essentially has the shape of a rectangle, which has an extension DBX in the longitudinal direction of the measurement scale 15 and an extension DBY transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis according to FIGS. 1 and 2).

[0101] In order to introduce a microstructure in the region B1, which represents one of the marking regions of the first track SP1 or of the second track SP2 of the measurement scale 15, a pulsed laser for generating a laser beam is provided, wherein the laser generates the laser beam by means of a sequence of several light pulses. The laser beam is directed at the first region B1 of the first side surface 2.1 in such a way that only a subregion of the first region B1 is irradiated by means of each individual light pulse of the generated sequence of several light pulses.

[0102] It is assumed in the example according to FIG. 3A that in a plane perpendicular to the propagation direction of the laser beam, the laser beam has an essentially circular beam profile with a diameter DL, so that, when impinging on the side surface 2.1, an individual light pulse of the laser beam irradiates a region of the side surface 2.1, which has the shape of a circle, with laser light, wherein, in the present example, the diameter of this region, which is irradiated by means of an individual light pulse, essentially corresponds to the diameter DL of the laser.

[0103] It is assumed in the present example that, when an individual light pulse of the laser beam impinges on the side surface 2.1, the side surface 2.1 is irradiated in such a way that the side surface 2.1 is changed in a circular region, which has the shape of a circle having a diameter D, due to the irradiation by means of the individual light pulse, in such a way that the side surface 2.1 has a change in the form of a spatial modulation in the above-mentioned circular region with the diameter D (compared to the shape of the surface prior to the irradiation by means of the respective individual light pulse). In the example according to FIG. 3A, a subregion of the first region B1, which is irradiated by means of the respective individual light pulse, is accordingly in each case illustrated as a region of the side surface 2.1, which is limited by a circle with the diameter D.

[0104] It is additionally assumed in particular in the example according to FIG. 3A that the laser beam is directed at the first region B1 of the first side surface 2.1 in such a way that the spatial extension D of the subregion of the first region B1, which is irradiated by means of the respective individual light pulse, in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) is smaller than the spatial extension DBX of the first region B1 in the longitudinal direction of the measurement scale 15, and that the spatial extension D of the subregion, which is irradiated by means of the respective individual light pulse, transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis), is smaller than the spatial extension DBY of the first region B1 transverse to the longitudinal direction of the measurement scale 15.

[0105] In the example according to FIG. 3A, the laser beam is moved relative to the guide rail 2 in such a way that at least several of the light pulses of the generated sequence of several light pulses irradiate several different subregions of the first region B1, which are arranged spatially distributed relative to one another, sequentially in time, wherein, for each individual one of the several different irradiated subregions, at least one other one of the several different irradiated subregions is present, which is offset to the respective individual one of the several different irradiated subregions in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) and/or transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) in such a way that the respective individual one of the several different irradiated subregions and the at least one other one of the several different irradiated subregions have an overlap, and wherein the several different irradiated subregions together form a region of the first side surface, which is congruent with the first region B1.

[0106] According to this, the laser beam is moved two-dimensionally (i.e. in the direction of the X axis and in the direction of the Y axis) over the first region B1 of the first side surface 2.1 of the guide rail 2, which corresponds to a marking region of the measurement scale 15 to be applied, so that different subregions of the first region B1 are irradiated one after the other.

[0107] The irradiation of a subregion by means of one of the light pulses locally effects a slight removal and/or a spatial redistribution of the material (steel) forming the first side surface 2.1 of the guide rail 2, so that the shape of the surface in the irradiated subregion is changed after the irradiation by means of a light pulse. Due to the fact that the laser beam is moved over the first region B1 in such a way that each of the different irradiated subregions has to have an overlap with at least one other one of the irradiated subregions, it is attained that the first side surface 2.1 of the guide rail 2 in the first region B1 has a spatial modulation after the irradiation by means of the light pulses, so that the first side surface 2.1 in the first region B1 compared to its state prior to the irradiation by means of the light pulseshas an increased roughness. The irradiation of the first region by means of the light pulses provides for a microstructuring of the first side surface in such a way that a surface, which is smooth prior to the irradiation, has an arrangement of elevations (microstructure), which represents an essentially even roughening of the surface, in the first region B1, after the irradiation in the entire first region.

[0108] In the example according to FIG. 3A, the diameter DL of the laser beam or the diameter D of the subregions, which are in each case irradiated by means of a light pulse, of the first region B1, respectively, in relation to the extension DBX of the first region B1 in the longitudinal direction of the measurement scale 15 and in relation to the extension DBY of the first region B1 transverse to the longitudinal direction of the measurement scale 15 is selected in such a way that

D<DBX<2D and

D<DBY<n D,

wherein n is a natural number (with n?2).

[0109] It is furthermore assumed that the different subregions, which are in each case irradiated by means of a light pulse, are arranged in the first region B1 in such a way that a first group of subregions of the entirety of all irradiated subregions with a number of a total of n subregions is present, wherein the individual subregions of these first groups are arranged in a row extending transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) and are thereby arranged relative to one another in such a way that the center points of the different subregions are offset relative to one another by predetermined distances, in each case transverse to the longitudinal direction of the measurement scale 15. As illustrated in FIG. 3A, the above-mentioned first group of subregions in its entirety forms a first line-shaped section of the first region B1, which is identified with the reference numeral D in FIG. 3A, the extension of which transverse to the longitudinal direction of the measurement scale 15 is identical to the extension DBY of the first region B1, and the extension of which in the longitudinal direction of the measurement scale 15 is identical to the diameter D of the subregions, which are in each case irradiated by means of a light pulse.

[0110] It is important to point out that not all of the subregions, which are arranged in the first line-shaped section L1, of the above-mentioned first group of subregions are illustrated in FIG. 3A: Only four of the respective subregions of the above-mentioned first group of subregions are illustrated graphically (for the sake of clarity of the illustration), wherein these four subregions are identified with the reference numerals TB11, TB15, TB16, and TB1n in FIG. 3A. The two subregions TB11 and TB1n are thereby arranged offset relative to one another in the direction of the Y axis in such a way that the subregion TB11 is arranged on one end of the first line-shaped section L1 with respect to the Y axis, and the subregion TB1n is arranged on the other end of the first line-shaped section L1 (i.e. located opposite the subregion TB11). The two subregions TB15 and TB16 are arranged relative to one another in such a way that the center point of the subregion TB16 is offset by a distance ?Y relative to the center point of the subregion TB15 in the direction of the Y axis. In the present example, the distance ?Y is selected in such a way that the distance ?Y is preferably greater than or equal to half the diameter D of the subregions, which are in each case irradiated by means of a light pulse, and the distance ?Y is preferably smaller than 80% of the diameter D of the subregions, which are in each case irradiated by means of a light pulse (i.e. D/2??Y<0.8*D). The two subregions TB15 and TB16 thus have an overlap, which is illustrated as a shaded area in FIG. 3A which is identified with the reference numeral UY. In the direction of the Y axis, the overlap UY has an extension DUY, which preferably lies in the range of 20-50% of the spatial extension D of the subregion, which is irradiated by means of an individual light pulse, in the direction of the Y axis.

[0111] The extension DUY is associated with the diameter D of the subregions, which are in each case irradiated by means of a light pulse, and with the above-mentioned distance ?Y according to the following equation: DUY=D?Y.

[0112] With regard to those subregions of the above-mentioned first group of subregions, which are not illustrated in FIG. 3A, it shall be pointed out that the center points of the different subregions relative to one another can in each case be offset transverse to the longitudinal direction of the measurement scale 15 in such a way that for each individual one of the different subregions, which is irradiated by means of a light pulse, another subregion is present, which is irradiated by means of a light pulse and the center point of which transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) is offset relative to the center point of the respective individual one of the different subregions, which are irradiated by means of a light pulse, by a distance, which corresponds to the distance ?Y illustrated in FIG. 3A between the center points of the subregions TB15 and TB16. Each of the subregions of the above-mentioned first group of subregions accordingly has an overlap at least with another subregion of the above-mentioned first group of subregions, which corresponds to the overlap UY of the subregions TB15 and TB16 illustrated in FIG. 3A.

[0113] As can be seen from FIG. 3A, the different subregions, which are in each case irradiated by means of a light pulse, are arranged in the first region B1 in such a way that additionally to the above-described first group of subregions, a second group of subregions of the entirety of all irradiated subregions is present with a number of a total of n subregions, wherein the individual subregions of this second group are arranged in a row extending transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) and are thereby arranged relative to one another in such a way that the center points of the different subregions are likewise offset relative to one another in each case transverse to the longitudinal direction of the measurement scale 15 by specified distances. As illustrated in FIG. 3A, the above-mentioned second group of subregions in its entirety forms a second line-shaped section of the first region B1, which is identified with the reference numeral L2 in FIG. 3A, the extension of which transverse to the longitudinal direction of the measurement scale 15 is identical to the extension DBY of the first region B1, and the extension of which in the longitudinal direction of the measurement scale 15 is identical to the diameter D of the subregions, which are in each case irradiated by means of a light pulse.

[0114] As suggested in FIG. 3A, the individual subregions, which are irradiated by means of light pulses, of the second group of subregions are arranged in the second line-shaped section L2 of the first region B1 transverse to the longitudinal direction of the measurement scale 15 so as to be spatially distributed in a way, which, analogously to the spatial distribution of the individual subregions, which are irradiated by means of light pulses, corresponds to the first group of subregions in the first line-shaped section L1 in the direction of the Y axis.

[0115] Likewise, not all of the subregions of the second group of subregions, which are arranged in the second line-shaped section L1, are illustrated in FIG. 3A: Only four of the respective subregions of the above-mentioned second group of subregions are illustrated graphically (for the sake of clarity of the illustration), wherein these four subregions are identified with the reference numerals TB21, TB25, TB26, and TB2n in FIG. 3A. The two subregions TB21 and TB2n are thereby arranged offset relative to one another in the direction of the Y axis in such a way that the subregion TB21 is arranged on one end of the second line-shaped section L2 with respect to the Y axis and the subregion TB2n is arranged on the other end of the second line-shaped section L2 (i.e. located opposite the subregion TB21).

[0116] Moreover, the center points of the different subregions of the second group of subregions are arranged offset relative to one another in the second line-shaped section L2 of the first region B1 in each case transverse to the longitudinal direction of the measurement scale 15 in such a way that for each individual one of the different subregions, which are irradiated by means of a light pulse, another subregion is present, which is irradiated by means of a light pulse and the center point of which, transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis), is offset relative to the center point of the respective individual one of the different subregions, which are irradiated by means of a light pulse, by a distance, which corresponds to the distance ?Y illustrated in FIG. 3A between the center points of the subregions TB15 and TB16. Each of the subregions of the second group of subregions accordingly has an overlap with another subregion of the second group of subregions, which corresponds to the overlap UY of the subregions TB15 and TB16 illustrated in FIG. 3A.

[0117] As mentioned, the diameter DL of the laser beam or the diameter D of the subregions of the first region B1, respectively, which are in each case irradiated by means of a light pulse, in relation to the extension DBX of the first region B1 in the longitudinal direction of the measurement scale 15, is selected in such a way in the example according to FIG. 3A that the relation D<DBX<2 D is fulfilled. Due to the fact that the first line-shaped section L1 of the first region B1 as well as the second line-shaped section L2 of the first region B1 have an extension in the longitudinal direction of the measurement scale 15, which is identical to the diameter D of the subregions, which are in each case irradiated by means of a light pulse, the subregions of the first group of subregions and the subregions of the second group of subregions are arranged relative to one another in such a way that the center points of the subregions of the first group of subregions lie on a first straight line extending in the direction of the Y axis, and the center points of the subregions of the second group of subregions lie on a second straight line, which likewise extends in the direction of the Y axis, wherein the first straight line and the second straight line are arranged parallel to one another, and, in the longitudinal direction of the measurement scale 15, have a distance ?X, which is smaller than the diameter D of the subregions, which are in each case irradiated by means of a light pulse.

[0118] The first line-shaped section L1 of the first region B1 and the second line-shaped section L2 of the second region B1 accordingly have an overlap, which extends in the direction of the Y axis over a length, which corresponds to the extension DBY of the first region B1 in the direction of the Y axis, and which extends in the longitudinal direction of the measurement scale 15 over a length DUX (illustrated in FIG. 3A). The extension DUX of the overlap of the first line-shaped section L1 of the first region B1 and of the second line-shaped section L2 of the first region B1 in the longitudinal direction of the measurement scale 15 is associated with the diameter D of the subregions, which are in each case irradiated by means of a light pulse, and with the above-mentioned distance ?X according to the following equation: DUX=D??X.

[0119] The subregions of the first group of subregions and the subregions of the second group of subregions are accordingly arranged relative to one another in such a way that each subregion of the first group of subregions generally has an overlap with at least one subregion of the second group of subregions, which has an extension in the longitudinal direction of the measurement scale 15, which is identical to the above-mentioned extension DUX of the overlap between the first line-shaped section L1 of the first region B1 and the second line-shaped section L2 of the second region B1 in the longitudinal direction of the measurement scale 15.

[0120] It is accordingly illustrated in an exemplary manner in FIG. 3A that the subregion TB11 and the subregion TB21 are arranged offset in the longitudinal direction of the measurement scale 15 in such a way that the subregion TB11 and the subregion TB21 have an overlap, which is illustrated in FIG. 3A as a shaded area, which is identified with the reference numeral UX. In the direction of the X axis, this overlap UX has an extension, which is identical to the above-mentioned extension DUX.

[0121] It is additionally illustrated in an exemplary manner in FIG. 3A that the subregion TB1n and the subregion TB2n are arranged offset in the longitudinal direction of the measurement scale 15 in such a way that the subregion TB1n and the subregion TB2n have an overlap, which is illustrated in FIG. 3A as a shaded area, which is likewise identified with the reference numeral UX. In the direction of the X axis, this overlap UX accordingly has an extension, which is identical to the above-mentioned extension DUX.

[0122] It is additionally illustrated in an exemplary manner in FIG. 3A that the subregion TB15 and the subregion TB25 are arranged offset in the longitudinal direction of the measurement scale 15 in such a way that the subregion TB15 and the subregion TB25 have an overlap, which is illustrated as a shaded area in FIG. 3A, which is likewise identified with the reference numeral UX and which, in the direction of the X axis, accordingly has an extension, which is identical to the above-mentioned extension DUX.

[0123] As moreover illustrated in FIG. 3A, the subregion TB16 and the subregion TB26 are arranged offset in the longitudinal direction of the measurement scale 15 in such a way that the subregion TB16 and the subregion TB26 have an overlap, which is illustrated as a shaded area in FIG. 3A, which is likewise identified with the reference numeral UX, and which, in the direction of the X axis, accordingly has an extension, which is identical to the above-mentioned extension DUX.

[0124] As can be seen from FIG. 3A, the two subregions TB25 and TB26 are arranged relative to one another in such a way that the center point of the subregion TB26 is offset by the distance ?Y relative to the center point of the subregion TB25 in the direction of the Y axis, so that the two subregions TB25 and TB26 have an overlap in the direction of the Y axis, which is illustrated as a shaded area in FIG. 3A, which is identified with the reference numeral UY.

[0125] As can be seen from FIG. 3A, the subregions TB15, TB16, TB25, and TB26 of the first region B1, which are irradiated by means of a respective individual light pulse, accordingly have overlaps UX and UY in two dimensions (i.e. in the longitudinal direction of the at least one track as well as transverse to the longitudinal direction of the at least one track).

[0126] All of the subregions of the first region B1, which are irradiated by means of an individual light pulse, accordingly each have overlaps UX and UY in two dimensions (i.e. in the longitudinal direction of the at least one track as well as transverse to the longitudinal direction of the at least one track).

[0127] The distance ?X is preferably selected in such a way that the extension DUX of the overlap UX in the direction of the X axis preferably lies in the range of 20-50% of the spatial extension D of the subregion, which is irradiated by means of an individual light pulse, in the direction of the X axis.

[0128] FIG. 3B showssimilarly as FIG. 3A (in a top view onto the side surface 2.1) a first region B2 of the side surface 2.1, in which the side surface 2.1 is to be treated with the help of a pulsed laser, in order to form a microstructure in the first region B2, which represents one of the marking regions of the first track SP1 or of the second track SP2 of the measurement scale 15.

[0129] Similarly as in the example according to FIG. 3A, it is assumed in the example according to FIG. 3B that the first region B2 essentially has the shape of a rectangle, which has an extension DBX in the longitudinal direction of the measurement scale 15, and an extension DBY transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis according to FIGS. 1 and 2).

[0130] Similarly as in the example according to FIG. 3A, a pulsed laser for generating a laser beam is provided in the example according to FIG. 3B for producing a microstructure, which is to be formed in the region B2, wherein the laser generates the laser beam by means of a sequence of several light pulses, and the laser beam is directed at the first region B2 of the first side surface 2.1 in such a way that only a subregion of the first region B2 is irradiated by means of each individual light pulse of the generated sequence of several light pulses.

[0131] Similarly as in the example according to FIG. 3A, it is assumed in the example according to FIG. 3B that in a plane perpendicular to the propagation direction of the laser beam, the laser beam has an essentially circular beam profile with a diameter DL, so that, when impinging on the side surface 2.1, an individual light pulse of the laser beam irradiates a region of the side surface 2.1, which has the shape of a circle, with laser light, wherein, in the present example, the diameter of this region, which is irradiated by means of an individual light pulse, essentially corresponds to the diameter DL of the laser.

[0132] Similarly as in the example according to FIG. 3A, it is assumed in the example according to FIG. 3B that, when an individual light pulse of the laser beam impinges on the side surface 2.1, the side surface 2.1 is irradiated in such a way that the side surface 2.1 is changed in a circular region, which has the shape of a circle having a diameter D, due to the irradiation by means of the individual light pulse, in such a way that the side surface 2.1 has a change in the form of a spatial modulation in the above-mentioned circular region with the diameter D (compared to the shape of the surface prior to the irradiation by means of the respective individual light pulse). In the example according to FIG. 3B, a subregion of the first region B2, which is irradiated by means of the respective individual light pulse, is accordingly in each case illustrated as a region of the side surface 2.1, which is limited by a circle with the diameter D.

[0133] Similarly as in the example according to FIG. 3A, it is additionally assumed in the example according to FIG. 3B that the laser beam is directed at the first region B2 of the first side surface 2.1 in such a way that the spatial extension D of the subregion of the first region B2, which is irradiated by means of the respective individual light pulse, in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) is smaller than the spatial extension DBX of the first region B2 in the longitudinal direction of the measurement scale 15, and that the spatial extension D of the subregion, which is irradiated by means of the respective individual light pulse, transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis), is smaller than the spatial extension DBY of the first region B2 transverse to the longitudinal direction of the measurement scale 15.

[0134] The example according to FIG. 3B essentially differs from the example according to FIG. 3A in that even though the extension DBY of the first region B2 according to FIG. 3B transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) is identical to the extension of the first region B1 according to FIG. 3A transverse to the longitudinal direction of the measurement scale 15, the spatial extension DBX of the first region B2 in the longitudinal direction of the measurement scale 15 is to be essentially larger, however, than the extension of the first region B1 according to FIG. 3A in the longitudinal direction of the measurement scale 15. The latter accounts for the requirement that the measurement scale 15 has different marking regions in the region of the second track SP2, the extensions of which in the longitudinal direction of the measurement scale 15 are different to a significant extent.

[0135] In the example according to FIG. 3A, it is accordingly assumed that the spatial extension DBX of the first region B2 in the longitudinal direction of the measurement scale 15 is to be significantly larger than twice the spatial extension D of the subregion of the first region B2, which is irradiated by means of the respective individual light pulse, in the longitudinal direction of the measurement scale 15 (i.e. DBX?2*D).

[0136] In the example according to FIG. 3B, the laser beam is likewise moved relative to the guide rail 2 in such a way that at least several of the light pulses of the generated sequence of several light pulses irradiate several different subregions of the first region B2, which are arranged so as to be spatially distributed relative to one another, sequentially in time, wherein, for each individual one of the several different irradiated subregions, at least one other one of the several different irradiated subregions is present, which is offset to the respective individual one of the several different irradiated subregions in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) and/or transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) in such a way that the respective individual one of the several different irradiated subregions and the at least one other one of the several different irradiated subregions have an overlap, and wherein the several different irradiated subregions together form a region of the first side surface, which is congruent with the first region B2.

[0137] In the example according to FIG. 3B, the laser beam is thus likewise moved two-dimensionally (i.e. in the direction of the X axis and in the direction of the Y axis) over the first region B2 of the first side surface 2.1 of the guide rail 2, which corresponds to a marking region of the measurement scale 15 to be applied, so that different subregions of the first region B2 are irradiated one after the other.

[0138] In contrast to the example according to FIG. 3A, it is assumed in the example according to FIG. 3B that due to the relatively large spatial extension DBX of the first region B2 in the longitudinal direction of the measurement scale 15, compared to the spatial extension D of the subregion, which is irradiated by means of the respective individual light pulse, the different subregions, which are in each case irradiated by means of a light pulse, are arranged in the first region B2 in such a way that more than two different groups of subregions of the entirety of all irradiated subregions are present, wherein each of these more than two different groups of subregions in each case comprises several of the subregions (with a number n of subregions as in the example according to FIG. 3A) and the individual subregions of each of the more than two different groups are arranged in a row extending transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis) and are thereby arranged relative to one another in such a way that the center points of the different subregions are offset relative to one another by predetermined distances, in each case transverse to the longitudinal direction of the measurement scale 15. The more than two different groups of subregions thereby differ in that the center points of the subregions of one of the different groups of subregions are offset relative to the center points of the subregions of every other one of the different groups of subregions in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) by predetermined distances.

[0139] In the example according to FIG. 3B, it is assumed that seven different groups of subregions are present (alternatively, more or fewer different groups could be present). As illustrated in FIG. 3B, the respective subregions of each of the seven different groups of subregions in each case form a line-shaped section of the first region B2, the extension of which transverse to the longitudinal direction of the measurement scale 15 is identical to the extension DBY of the first region B2, and the extension of which in the longitudinal direction of the measurement scale 15 is identical to the diameter D of the subregions, which are in each case irradiated by means of a light pulse.

[0140] Due to the fact that the center points of the subregions of one of the seven different groups of subregions are offset relative to the center points of the subregions of every other one of the seven different groups of subregions in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) by predetermined distances, the subregions of the seven different groups form a total of seven line-shaped sections of the first region B2, which are identified in FIG. 3B with the reference numerals L1, L2,L3, L4, L5, L6 or L7, respectively.

[0141] The individual subregions, which are irradiated by means of a light pulse and which are in each case assigned to one of the seven line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, of the first region B2, are not illustrated in FIG. 3B. It is assumed in this context that the arrangement of the individual subregions, which are irradiated by means of a light pulse, of the seven line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, is analogous to the arrangement of the individual subregions, which are irradiated by means of a light pulse, in the first line-shaped section L1 or in the second line-shaped section L2, respectively, of the first region B1 according to FIG. 3A.

[0142] As suggested in FIG. 3B, the center points of the individual subregions, which are irradiated by means of a light pulse, in each of the seven line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, of the first region B2 in each case lie on a straight line, which extends in the direction of the Y axis. In the example according to FIG. 3B, seven line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, of the first region B2 are arranged relative to one another in such a way that the center points of those subregions, which are irradiated by means of a light pulse and which are assigned to the line-shaped section L1, relative to the center points of those subregions, which are irradiated by means of light pulses and which are assigned to the line-shaped section L2, with respect to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) have a distance ?X, which is smaller than the diameter D of the subregions, which are in each case irradiated by means of a light pulse. The center points of those subregions, which are irradiated by means of a light pulse and which are assigned to the line-shaped section L2, relative to the center points of those subregions, which are irradiated by means of a light pulse and which are assigned to the line-shaped section L3, with respect to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis) accordingly likewise have the above-mentioned distance ?X. The remaining line-shaped sections L4, L5, L6 or L7, respectively, of the first region B2 are arranged in an analogous way relative to the line-shaped sections L1, L2 and L3 of the first region B2: The center points of the individual subregions, which are irradiated by means of a light pulse, of the seven line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, in each case lie on different straight lines, which extend in the direction of the Y axis and which are in each case arranged equidistantly one after the other in the longitudinal direction of the measurement scale 15, wherein the distance between two respective adjacent ones of these straight lines corresponds to the above-mentioned distance ?X (as illustrated in FIG. 3B).

[0143] Due to the fact that it is assumed that the distance ?X is smaller than the diameter D of the subregions, which are in each case irradiated by means of a light pulse, the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, of the first region B2 are arranged to be offset in the longitudinal direction of the measurement scale 15 in such a way that each of the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, in each case has an overlap with another one of the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, which is illustrated in FIG. 3B as a shaded area and which is in each case identified with the reference numeral UX. In the direction of the X axis, the respective overlap UX between two respective ones of the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, accordingly has an extension DUX, which is associated with the above-mentioned distance ?X according to the following equation: DUX=D?X.

[0144] Each of the subregions, which is irradiated by means of a light pulse and which is assigned to one of the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, accordingly has an overlap with at least one other subregion, which is irradiated by means of a light pulse and which is assigned to another one of the line-shaped sections L1, L2, L3, L4, L5, L6 or L7, respectively, in the region of one of the overlaps UX illustrated in FIG. 3B.

[0145] In the example according to FIG. 3B, the distance ?X is preferably selected in such a way that the extension DUX of the overlap UX in the direction of the X axis preferably lies in the range of 20-50% of the spatial extension D of the subregion, which is irradiated by means of an individual light pulse, in the direction of the X axis.

[0146] Realizations of a measurement scale 15 illustrated in FIGS. 1 and 2 on a side surface of a guide rail (made of steel) will be described below with reference to FIGS. 4-7.

[0147] FIGS. 4-7 show realizations of a measurement scale 15 illustrated in FIGS. 1 and 2 on a side surface of a guide rail of a profile rail guide, in the case of which a short-pulse laser, for example, with a wavelength of 355 nm and a maximum output power of 300 mW as well as a pulse duration of less than 15 nanoseconds and an aperture opening of 16 mm was used for introducing the microstructure in the respective marking regions of the measurement scale 15 on the side surface of the guide rail. To introduce the microstructure, it was possible to move the laser beam at a scan speed of 200 mm per second relative to the guide rail, wherein the laser generated a sequence of light pulses with a repetition rate (pulse frequency) of 60 kHz, and generally 90% of the maximum output power was selected for the laser power.

[0148] The laser beam had a circular profile and was applied to the side surface of the guide rail in such a way that an individual light pulse of the laser beam on the side surface of the guide rail irradiated a subregion with a diameter D of approx. 8 ?m.

[0149] FIG. 4 shows a top view through a microscope onto a measurement scale 15 according to FIG. 2, which is applied to a side surface of a guide rail by means of the method according to the invention with the help of the above-mentioned short-pulse laser. The upper half of FIG. 4 shows a top view onto the first track SP1 (incremental track) of the measurement scale 15, and the lower half of FIG. 4 shows a top view onto the second track SP2 (reference track) of the measurement scale 15.

[0150] The bright regions in FIG. 4 correspond to the respective mirror regions of the measurement scale 15, while the dark regions in FIG. 4 show the respective marking regions of the measurement scale 15, which were applied by means of the above-mentioned short-pulse laser to the side surface of the guide rail.

[0151] The side surface illustrated in FIG. 4 was polished prior to the application of the measurement scale 15, so that the average roughness value (Ra) of the side surface was Ra=0.007 ?m (measured by means of a laser scanning microscope). The individual marking regions of the first track SP1 (incremental track) illustrated in the upper half in FIG. 4 have an extension of approximately 100 ?m in the longitudinal direction of the measurement scale 15 (i.e. in the direction of the X axis of a coordinate system specified in FIG. 4).

[0152] The marking regions of the measurement scale 15 illustrated in FIG. 4 were provided according to the example illustrated in FIG. 3B, whereby the parameters D and ?X were selected as follows: D=8 ?m and ?X=5 ?m.

[0153] In the case of the side surface illustrated in FIG. 4, the irradiation by means of the laser pulses had the effect that the side surface in the respective marking regions experienced a roughening, which is homogenous over the entire area of the respective marking regions, whereby the average roughness value (Ra) in the marking regions was Ra=0.162 ?m (measured by means of a laser scanning microscope).

[0154] As a result of this roughening, the respective marking regions of the measurement scale illustrated in FIG. 4 do not show a direct reflection of the light, which is incident on the marking regions (for example perpendicular to the side surface) and can thus be seen in FIG. 4 as homogenous dark (black) surface areas in a light, which is incident essentially perpendicular to the side surface.

[0155] FIG. 5 shows a top view through a microscope onto a measurement scale 15 as in FIG. 4, which is applied to a side surface of a guide rail by means of the method according to the invention with the help of the above-mentioned short-pulse laser, but with a lager magnification, so that the outer contours of the respective marking regions and of the respective mirror regions of the measurement scale 15 can be seen more clearly. A total of five of the marking regions of the first track SP1 (incremental track) of the measurement scale 15 can be seen in FIG. 5 in an upper region of FIG. 5, and a total of two of the marking regions of the second track SP2 (reference track) of the measurement scale 15 can be seen on the lower edge of FIG. 5. Upon detailed observation of the marking regions, which are applied by means of the short-pulse laser, it can be seen that due to the impact of the light pulse generated by the short-pulse laser, material residues are created (in the form of small particles adhering to the surface), which can protrude into the respective adjacent (polished) mirror regions on the outer edges of the marking regions. This has the result that the respective marking regions do not appear to be limited cleanly in a straight line on their edges in the view according to FIG. 5. The latter can relate, for example, to edges of the marking regions, which, in the illustration according to FIG. 5, in each case extend transverse to the longitudinal direction of the measurement scale 15 (i.e. in the direction of the Y axis of a coordinate system specified in FIG. 5), and thus have an impact on the measuring accuracy of a linear encoder, which is based on an optical scanning of the measurement scale 15 in the longitudinal direction of the measurement scale 15.

[0156] Material residues of the above-mentioned type, which can be created during the application of the marking regions by means of a short-pulse laser of the above-mentioned type, can be removed completely by means of a surface cleaning process with a suitable cleaning agent.

[0157] It is furthermore important to point out that an irradiation of a surface of a guide rail consisting of the material steel or stainless steel, respectively, by means of the light pulses of the short-pulse laser can have the effect that a chromium depletion (i.e. a reduction of the concentration of the portions of chromium contained in the steel) can be induced at the surface in the respective irradiated region. A chromium depletion of this type can reduce the corrosion resistance of the surface of the guide rail (in particular in the marking regions of the measurement scale) and would thus be disadvantageous with respect to a desirable resistance of the measurement scale, which is as long-term as possible. In order to counteract the above-mentioned effect, a passivation of the side surface can preferably be performed by means of a suitable passivation agent after the application of the measurement scale to the side surface of the guide rail.

[0158] For example, a highly alkaline cleaner, which is known under the name deconex MT 19, which is produced and sold by the company Borer Chemie AG, Gewerbestrasse 13, 4528 Zuchwil, is suitable for the above-mentioned purpose as a cleaning agent for cleaning stainless steel surfaces.

[0159] For example, a highly acidic cleaner, which is known under the name deconex MT 41, which is likewise produced and sold by the above-mentioned company Borer Chemie AG, is suitable for the above-mentioned purpose as a passivation agent for passivating stainless steel surfaces.

[0160] In particular the following sequential cleaning process has turned out to be suitable for cleaning and passivating the side surface of the guide rail after the application of the measurement scale 15 to the side surface with the help of a short-pulse laser of the above-mentioned type: [0161] 1. cleaning using deconex MT 19, 2% concentration at 55? C. and 25 kHz; 15 W/L; [0162] 2. passivating using deconex MT 41, 8% concentration at 55? C. and 40 kHz; 15 W/L; [0163] 3. rinsing with DI water at room temperature and 40 kHz; 15 W/L; and [0164] 4. drying at 100? C.

[0165] FIG. 6 shows a view of the measurement scale according to FIG. 5 after performance of the above-listed ultrasonic cleaning process. Compared to FIG. 5, it can be seen clearly that the marking regions are essentially limited in a straight line after performance of the above-mentioned cleaning process. Material residues, which protrude into the respective adjoining mirror regions, can no longer be seen on the outer edges of the marking regions.

[0166] FIG. 7 shows a section of the marking regions illustrated in FIG. 6 in a magnification, which shows structural details of the surface of the individual marking regions after performance of the above-listed ultrasonic cleaning process. In particular, a roughening of the surface, which is homogenous over the entire area of a marking region, can be seen.

[0167] As already mentioned, the roughness, which a side surface 2.1 of a guide rail 2 has prior to the application of a measurement scale 15 to the side surface 2.1 according to the described method, decisively influences the intensity of the reflected light RL1 or RL2, respectively, which reflects in a linear encoder 11 according to FIG. 1 on the respective mirror regions of the first track SP1 or on the respective mirror regions of the second track SP2, respectively, of the measurement scale 15, which is applied to the side surface 2.1 according to the described method, and which is detected by means of the respective photo sensors of the first arrangement 25.1 of photo sensors or the respective photo sensors of the second arrangement 25.2 of photo sensors, respectively. The roughness, which the side surface 2.1 of the guide rail 2 has prior to the application of a measurement scale 15 to the side surface 2.1 according to the described method, accordingly also decisively influences the size of the respective output signals, which the respective photo sensors of the first arrangement 25.1 of photosensors generate in each case during the detection of the light RL1 reflected on the first track SP1 of the measurement scale 15 or the respective photo sensors when detecting the light RL2 reflected on the second track SP2 of the measurement scale 15, respectively. The roughness, which the side surface 2.1 of the guide rail 2 has prior to the application of a measurement scale 15 to the side surface 2.1 according to the described method, accordingly also decisively influences the amplitude of the variation, which the output signals of the respective photo sensors of the first arrangement 25.1 or the output signals of the respective photo sensors of the second arrangement 25.2, respectively, show in response to a movement of the measuring head 21 in the longitudinal direction of the guide rail 2 as a function of the respective position of the measuring head 21 with respect to the longitudinal direction of the guide rail 2.

[0168] In order to experimentally evaluate the above-mentioned influence of the roughness, which a side surface 2.1 of a guide rail 2 has prior to the application of a measurement scale 15 to the side surface 2.1 according to the described method, a measurement scale 15 illustrated in FIG. 2 was in each case applied to side surfaces 2.1 of several different guide rails 2 according to the described method, whereby a side surface 2.1 of one of the guide rails was ground according to standard prior to the application of the measurement scale 15, but was not polished (after the grinding according to standard), and a side surface 2.1 of other guide rails 2 was initially ground according to standard and subsequently polished additionally (after the grinding according to standard), in particular by means of a pre-polishing by means of a ceramic grinding disk with a very fine grain size (400 or finer) and subsequent polishing by means of a polishing disk bound on the basis of rubber or synthetic resin, or alternatively by means of polishing by means of polishing brushes.

[0169] The measurement scale 15 was thereby in each case applied to the side surface 2.1 of the respective guide rail 2 by means of the same short-pulse laser, which served for the realization of the measurement scale 15 illustrated in FIGS. 4-7 (when using the same operating parameters of the short-pulse laser).

[0170] The laser beam accordingly had a circular profile and was applied to the side surface 2.1 of the respective guide rail 2 in such a way that an individual light pulse of the laser beam irradiated a subregion with a diameter D of approx. 8 ?m on the side surface 2.1 of the respective guide rail. The marking regions of the respective measurement scale 15 were provided according to the example illustrated in FIG. 3B, whereby the parameters D and ?X were selected as follows: D=8 ?m and ?X=5 ?m. The first track SP1 of the respective measurement scale 15 was thereby in each case realized in such a way that the individual marking regions M and the individual mirror regions S of the measurement scale 15 in each case have an extension of approx. 100 ?m in the longitudinal direction of the measurement scale 15.

[0171] Each individual one of the measurement scales 15, which are provided in this way on side surfaces 2.1 of different guide rails, was subsequently combined with a sensor device 20 illustrated in FIG. 1, in order to form a distance measuring system 10 illustrated in FIG. 1.

[0172] To characterize each individual one of the measurement scales 15, which are provided in this way on side surfaces 2.1 of different guide rails 2, each individual one of these measurement scales 15 was optically scanned by means of the sensor device 20, wherein the sensor device 20 (as described in connection with FIG. 1) was moved in the longitudinal direction of the respective measurement scale 15, the respective measurement scale 15 was illuminated thereby by means of a light beam 22.1 emitted by the light source 22, and the light RL1 reflected on the respective mirror regions of the first track SP1 was detected with the help of the photo sensors of the first arrangement 25.1 of photo sensors of the electronic light sensor chip 25.

[0173] The first arrangement 25.1 of photo sensors was thereby formed in such a way that the photo sensors of the first arrangement 25.1 of photo sensors in each case generate an output signal, which varies periodically between a maximum signal value Smax and a minimum signal value Smin as a function of the position of the sensor device 20 with respect to the longitudinal direction of the measurement scale 15, in response to a movement of the sensor device 20 in the longitudinal direction of the respective measurement scale 15, with a periodic variation, which corresponds to the course of a mathematical sine function or cosine function, respectively. In order to characterize this periodic variation of the respective output signal of one of the photo sensors of the first arrangement 25.1 of photo sensors, it is expedient to determine a signal contrast K of the respective output signal of one of the photo sensors of the first arrangement 25.1 of photo sensors, which, in this connection, can be defined as the ratio from the amplitude (Smax?Smin)/2 of the variation of the respective output signal as a function of the position of the sensor device 20 with respect to the longitudinal direction of the measurement scale 15 and the difference between an average value (i.e. (Smax+Smin)/2) of the respective output signal and a base output signal S0 of the respective photo sensor, i.e. the output signal of the respective photo sensor measured under the condition that the light source 22 is turned off and thus does not generate a light beam for illuminating the measurement scale 15, i.e. the signal contrast K of the respective output signal of one of the photo sensors of the first arrangement 25.1 is calculated as

K=(Smax?Smin)/(Smax+Smin?2*S0).

[0174] The signal contrast K generally assumes a value between 0 and 1.

[0175] The roughness, which a side surface 2.1 of a guide rail 2 has prior to the application of a measurement scale 15 to the side surface 2.1 according to the described method, has a significantly measurable influence on the size of the above-mentioned signal contrast K of the respective output signal of one of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20.

[0176] In the case of the measurement scale 15, which was applied to a side surface 2.1 of the guide rail 2 according to the described method, which was ground only according to standard prior to the application of the measurement scale 15, but which (after the grinding according to standard) was not polished, the respective output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 showed a signal contrast K=0.29 when optically scanning the first track SP1 of the measurement scale 15.

[0177] In the case of the measurement scales 15, which were applied to a side surface 2.1 of guide rails 2 according to the described method and which were initially ground according to standard prior to the application of the respective measurement scale 15 and were additionally polished subsequently (after the grinding according to standard), the respective output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 in each case showed a signal contrast K in the range of 0.5 to 0.65 (as a function of the respectively used method for polishing the side surface 2.1 of the respective guide rail 2 and accordingly of the size of the reduction, which is in each case attained by means of the polishing, of the roughness of the respective side surface 2.1, to which the respective measurement scale 15 was applied according to the described method), in response to the optical scanning of the first track SP1 of the respective measurement scale 15.

[0178] By means of a polishing of the side surface 2.1 prior to the application of the respective measurement scale 15, the signal contrast K of the output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 can accordingly be increased significantly in response to the optical scanning of the first track SP1 of the respective measurement scale 15. The respective size of the above-mentioned signal contrast K is relevant for the measuring accuracy of the distance measuring system 10 illustrated in FIG. 1 or of the linear encoder 11 illustrated in FIG. 1, respectively: The larger the signal contrast K, the larger the accuracy, with which the respective position of the sensor device 20 can be determined with respect to the longitudinal direction of the respective measurement scale 15 by means of an evaluation of the output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20.

[0179] As mentioned, it is in each case provided in the above-mentioned embodiments of the measurement scale 15 to provide the individual marking regions of the measurement scale 15 on a side surface 2.1 in such a way that all subregions of the respective marking region M, which are irradiated by means of an individual light pulse, in each case have overlaps UX and UY in two dimensions (i.e. in the longitudinal direction of the at least one track as well as transverse to the longitudinal direction of the at least one track). The respective overlaps UX and UY between the different irradiated subregions have an impact on the reflectivity of the respective marking regions M compared to the reflectivity of the individual mirror regions S. The reflectivity of the respective marking regions M can in particular be minimized by means of a suitable selection of the size of the respective overlaps UX and UY, which provides for an increase of the respective signal contrast K of the output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 during the optical scanning of the first track SP1 of the respective measurement scale 15.

[0180] In order to characterize the impact of the size of the respective overlaps of the different irradiated subregions of a marking region M, the impact of the size of the overlap UX on reflectivity of the respective marking regions M was evaluated in an exemplary manner.

[0181] For this purpose, three examples (hereinafter example 1, example 2, and example 3) were produced on a side surface 2.1 by means of the method according to the invention, in each case next to one another, for a first track SP1 of the measurement scale 15 of the type illustrated in FIG. 2, wherein the side surface 2.1 was polished evenly prior to the provision of the marking regions M of the different first tracks SP1 in the entire region of the side surface.

[0182] The laser beam thereby had a circular profile and was applied to the side surface 2.1 in such a way that an individual light pulse of the laser beam irradiated a subregion on the side surface 2.1. The marking regions of the respective measurement scale 15 were provided according to the example illustrated in FIG. 3B, wherein the parameters D and ?Y were selected as follows: D=15.2 ?m and ?Y=5 ?m. The first track SP1 of the respective measurement scale 15 was thereby in each case realized in such a way that the individual marking regions M and the individual mirror regions S of the measurement scale 15 in each case have an extension of approx. 100 ?m in the longitudinal direction of the measurement scale 15.

[0183] The above-mentioned embodiments of the first track SP1 according to example 1, example 2, or example 3, respectively, are accordingly identical with regard to the distance ?Y, which decisively determines the extension DUY of the overlap UY of the subregions, which are irradiated by means of a laser pulse, in each case transverse to the direction of the X axis or transverse to the longitudinal direction of the first track SP1, respectively (DUY=D-?Y=10.2 ?m in the present case).

[0184] The above-mentioned embodiments of the first track SP1 according to example 1, example 2, or example 3, respectively, differ with regard to the distance ?X, which decisively determines the extension DUX of the overlap UX in the direction of the X axis or in the longitudinal direction of the first track SP1, respectively. AX were thereby selected as follows: ?X=5 ?m for example 1; ?X=8 ?m for example 2, or ?X=15.2 ?m for example 3, respectively.

[0185] The above-mentioned embodiments of the first track SP1 according to example 1, example 2, or example 3, respectively, were in each case scanned by means of the above-described sensor device 20, and the respective output signals of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 were measured for each of these embodiments during the optical scanning of the first track SP1 of the measurement scale 15. The signal contrast K of the respective output signal of one of the photo sensors of the first arrangement 25.1 of photo sensors of the sensor device 20 was thereby determined in each case for each of the mentioned embodiments of the first track SP1 according to example 1, example 2, or example 3, respectively.

[0186] The respective determined values for the signal contrast K, the distance ?X, and the extension DUX of the overlap UX in the direction of the X axis or in the longitudinal direction of the first track SP1, respectively, are specified in the following Table 1 for the above-mentioned embodiments of the first track SP1 according to example 1, example 2, or example 3, respectively.

TABLE-US-00001 TABLE 1 D [?m] ?X [?m] DUX [?m] K (%) Example 1 15.2 5 10.2 61.4 Example 2 15.2 8 7.2 53.6 Example 3 15.2 15.2 0 51.6

[0187] As can be seen from Table 1, the different subregions, which are irradiated by means of a laser pulse, in the case of example 3, are distributed in a marking region M in such a way that the different subregions do not have an overlap UX in the longitudinal direction of the first track SP1 (i.e. DUX=0). In the case of example 1 and of example 2, in contrast, an overlap UX with DUX>0 is present in each case.

[0188] As can be seen from Table 1, the signal contrast K for examples 1 and 2 is in each case larger than the corresponding value for the signal contrast K for example 3. Compared to example 3 (with DUX=0), an enlargement of the extension DUX of the overlap UX in the longitudinal direction of the first track SP1 accordingly leads to an increase of the signal contrast K and thus to a reduction of the reflectivity of a marking region M.

[0189] It is important to point out that it is also conceivable as alternative for the above-mentioned short-pulse laser to use an ultra short-pulse laser with a pulse duration in the picosecond range, for example with a pulse duration of less than 10 picoseconds, in order to apply a measurement scale to a surface of a guide rail in accordance with the invention.

[0190] The use of an ultra short-pulse laser of this type provides for an application of the measurement scale with a reduced thermal stress of the surface regions irradiated by means of laser pulses. This results in the advantage that after the application of the measurement scale, a performance of the above-described method for cleaning and passivation can be forgone.

[0191] With reference to FIG. 1, it is important to point out that the guide rail 2 can be equipped with at least one and preferably with a plurality of blind holesstarting at the second side surface 2.2preferably comprising an internal thread, wherein the first side surface 2.1 of the guide rail 2 can in particular be formed without holes. The latter provides for a fastening of the guide rail 2 to any structure with the help of the above-mentioned blind holes (not illustrated in FIG. 1), whereby the entire surface of the first side surface 2.1 is available completely for the formation of the measurement scale.

[0192] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.