METHOD FOR ASSESSING THE QUALITY OF A COMPONENT OF OPTICAL MATERIAL

Abstract

A method and system for assessing the quality of at least one component of optical material which has at least one first center axis includes directing at least one light beam towards at least one detector device such that while changing the position and/or orientation of the component relative to the light beam, the light beam crosses at least from time to time the component and determining, with at least one determination device, at least one characterizing value of at least one figure of merit of the component based on analyzing, with at least one analyzing device, the dependency of a parameter of the light beam detected by the detector device on the position and/or orientation of the component.

Claims

1. A method for assessing the quality of at least one component of optical material which has at least one first center axis, the method comprising: directing at least one light beam towards at least one detector device such that while changing the position and/or orientation of the component relative to the light beam, the light beam crosses at least from time to time the component; and determining, with at least one determination device, at least one characterizing value of at least one figure of merit of the component based on analyzing , with at least one analyzing device, the dependency of a parameter of the light beam detected by the detector device on the position and/or orientation of the component.

2. The method according to claim 1, wherein directing the at least one light beam comprises routing the light beam from its at least one light source to the detector device via at least one optical element.

3. The method according to claim 1, wherein, when the light beam crosses the component, the light beam propagates through at least one thickness range of the component.

4. The method according to claim 1, wherein the light beam always crosses the component or crosses the component at different locations for different instances of time.

5. The method according to claim 1, wherein the component is fixedly attached to at least one positioning device, wherein changing the position and/or orientation of the component comprises actuating the positioning device or changing the position and/or orientation of the positioning device.

6. The method according to claim 1, wherein changing the position of the component comprises changing the position of the component along at least one first direction by displacing the positioning device along the first direction.

7. The method according to claim 1, wherein changing the position of the component comprises changing the position of the component along at least one second direction by displacing the positioning device along the second direction.

8. The method according to claim 1, wherein changing the orientation of the component comprises rotating the component around its first center axis or around at least one axis parallel to the incident or the exiting light beam.

9. The method according to claim 1, wherein changing the orientation of the component comprises rotating the component around its first center axis or around at least one axis parallel to the incident or the exiting light beam, by rotating the positioning device around the first center axis or around at least one axis parallel to the incident or the exiting light beam.

10. The method according to claim 1, wherein changing the position and/or orientation of the component comprises changing the position of the component along the first direction and changing the orientation of the component.

11. The method according to claim 1, wherein changing the position and/or orientation of the component comprises changing the position of the component along the first and the second direction.

12. The method according to claim 1, wherein the detector device has at least one detecting plane for detecting the light beam incident to the detector device

13. The method according to claim 1, wherein the parameter is at least one selected from the group consisting of: the area of at least one cross-section of the light beam that lies within the detecting plane of the detector device, the position of the cross-section of the light beam within the detecting plane, and the intensity distribution of the light beam in the detecting plane.

14. The method according to claim 1, wherein the figure of merit is directed to local inhomogeneities, such as at least one local thickness or at least one local refraction index, of, local deviation from a nominally ideal shaped component of, local deviation from a cylindric design of, local defects, such as bubbles or knots, in, local or global roundness of, local slope error of, local drawing lines on, local shape errors of, local artifacts of, local light transmission properties of, local striae of, local scratches on, local variation of physical thickness of, local variation of optical thickness of, or local impurities, such as stones or pieces of metal, in, respectively, the component.

15. The method according to claim 1, wherein analyzing the dependency comprises obtaining and evaluating the variation the parameter detected by the detector device has across the different positions and/or orientations of the component.

16. The method according to claim 1, wherein the parameter is a first coordinate value of the position of the cross-section of the light beam in the detecting plane and whose dependency on different positions along the first and/or second direction of the component and/or orientations of the component around its first center axis is analyzed for determining the characterizing value of the local deviation from a cylindrical design, the roundness, the slope error or the drawing lines, respectively, of the component.

17. The method according to claim 1, wherein the parameter is a second coordinate value of the position of the cross-section of the light beam in the detecting plane and whose dependency on different positions along the first and/or second direction of the component and/or orientations of the component around its first center axis is analyzed for determining the characterizing value of the local deviation from a cylindrical design, the roundness, the slope error or the drawing lines, respectively, of the component.

18. The method according to claim 1, wherein the parameter is the area of the cross-section of the light beam in the detecting plane and whose dependency on different positions along the first and/or second direction of the component and/or orientations of the component around its first center axis is analyzed for determining the characterizing value of local deviation from a cylindric design or local defects, respectively, of the component.

19. The method according to claim 1, wherein the parameter is the intensity distribution of the light beam in the detecting plane and whose dependency on different positions along the first and/or second direction of the component and/or orientations of the component around its first center axis is analyzed for determining the characterizing value of local defects or at least one light transmission property, respectively, of the component.

20. A System for assessing the quality of at least one component of optical material, the system comprising: at least one holder device for holding the component; at least one detector device; at least one light source that emits at least one light beam towards the at least one detector device such that the light beam crosses the component at least from time to time while the component is held by the holder device; at least one positioning device configured to change the position and/or orientation of the component relative to the light beam while the component is held by the holder device,; at least one analyzing device configured to analyze the dependency of one or more parameters of the light beam detected by the detector device on the position and/or orientation of the component; and at least one determination device configured to determine at least one characterizing value of at least one figure of merit of the component based on at least one result obtained from the analyzing device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0128] Various aspects of this disclosure will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, when read in light of the accompanying schematic drawings.

[0129] FIG. 1 shows a system according to the present disclosure in a first configuration for a first type of component for carrying out a method according to the present disclosure.

[0130] FIG. 2 shows a system according to the present disclosure in a second configuration for a second type of component for carrying out a method according to the present disclosure.

[0131] FIG. 3 shows a diagram of the variation of a selected parameter for components of the same type but of different quality.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0132] FIG. 1 shows a system 1 in a first configuration for assessing the quality of at least one component of optical material 3 of a first type.

[0133] The component (of optical material) 3 whose quality can be assessed with the system 1 is of cylindrical shape and has a shell (i.e. first type component). The component 3 has a first center axis which in FIG. 1 runs along a direction parallel to direction R1 (i.e. a vertical direction in FIG. 1).

[0134] The system 1 comprises a holder device 5 for holding the component 3. In FIG. 1 this holder device is in form of a table.

[0135] The system 1 comprises a detector device 7 and a light source 9 which emits a light beam 11, wherein the light beam 11 is directed towards the detector device 7 such that the light beam 11 crosses the component 3 at least from time to time if it is held by the holder device 5. The light source might be realized in form of a laser, for example having a wavelength of 633 nm.

[0136] The detector device 7 has a detecting plane for detecting the light beam 11 incident to the detector device 7. The detecting plane is perpendicular to the incident light beam 11. For example the detector device 7 comprises a 2D detector unit which comprises an array of pixels. This allows that the detector device 7 can determine the position, the shape and/or the intensity distribution of the cross-section of the light beam 11 in the detecting plane.

[0137] The system 1 further comprises a positioning device 13, for changing the position along the first direction R1 and the orientation of the component 3, while the component 3 is held by the holder device 5, relative to the light beam 11. The positioning device 13 is realized in form of a rotary and height-adjustable table (see the arrows indicated at the positioning device 13 for illustration purposes). Indeed, the holder device 5 is designed in one piece with at least one part of the positioning device 13, i.e. the table function as holder device 5 and at the same time also functions as positioning device 13.

[0138] The system 1 also comprises an analyzing device 15 which is configured to analyze the dependency of one or more parameters of the light beam 11 detected by the detector device 7 on the position and/or orientation of the component 3.

[0139] The system 1 also comprises a determination device 17 which is configured to determine at least one characterizing value of at least one figure of merit of the component 3 based on at least one result obtained from the analyzing device 15.

[0140] Indeed, the analyzing device 15 and the determination device 17 are designed as one single device which might be a personal computer having some hardware and some software installed. The analyzing device 15 and determination device 17 might be connected with each other and/or with the detector device 7 and the positioning device 13 as indicated by solid lines in FIG. 1 for the purpose of transmitting and exchanging control data and receiving data of the detector device 13.

[0141] In the system 1 the light beam 11 is directed from its light source 9 to the detector device 7 via an optical element 19. The optical element 19 comprises a prism such as a pentaprism but it might alternatively or in addition also comprise a mirror.

[0142] Optionally, the system 1 further comprises a filter 21 which is arranged within the light beam path before the detector device 7. The filter 21 might be in form of an attenuation filter for attenuating the incident light beam 11. Alternatively or in addition the filter might be in form of a scattered light filter to prevent scattered light reaching the detector device 7.

[0143] Inter alia due to one or more optional mounting elements 23, the system 1 experiences/undergoes a minimum oscillation/vibration during use.

[0144] In the system 1 the light beam 11 is incident on the optical element 19 along a direction parallel to the first center axis of the component 3, i.e. parallel to direction R1, and the light beam 11 is deflected by the optical element 19 in a direction perpendicular to the direction R1 of incidence of the light beam 11 (which is also a direction perpendicular to the first center axis of the component 3).

[0145] Of course, for the sake of completeness it is acknowledged that there might be possible modifications of system 1 so that for cylindrical components the light beam 11 is incident on the optical element 19 along a direction perpendicular to the first center axis of the component and where the light beam 11 is deflected by the optical element 19 in a direction parallel to the first center axis of the component. In other words, such a modification of system 1 might be suitable for scenarios where the cylindrical component 3 is rotated by 90 degrees in the picture plane of FIG. 1 along with an appropriate modification of the positioning device 13.

[0146] The light beam 11 always crosses the component 3 (particularly the shell thereof) and by displaying and/or rotating the component 3, the light beam 11 crosses the component at different locations. Hence, the detector device 7 can evaluate the quality of the component at different locations by evaluating the light beam. This allows an overall assessment of the quality of the component 3.

[0147] FIG. 2 shows a system 1′ in a second configuration for assessing the quality of at least one component of optical material 3′ of a second type.

[0148] The component (of optical material) 3′ whose quality can be assessed with the system 1′ is preferably of flat shape such as of cubic shape (i.e. second type component). The component 3′ has a first center axis which in FIG. 2 runs along a direction parallel to the direction R1′ (i.e. a vertical direction in FIG. 2).

[0149] Indeed, system 1′ is similar to system 1 described above with respect to FIG. 1. Hence, for the same structural features the same reference numerals are used, however, single dashed. It is, therefore, also sufficient to describe only the differences between system 1′ and system 1, while for the remainder, reference can be made to the description provided above with respect to system 1 in combination with FIG. 1.

[0150] In system 1′ the positioning device 13′ allows for changing the position of the component 3′ along the first direction R1′ and along a second direction R2′ (which is a direction perpendicular to the drawing plane of FIG. 2), while the component 3 is held by the holder device 5′, relative to the light beam 11′. The positioning device 13′ is realized in form of a X-Y-adjustable table (see the arrows indicated at the positioning device 13′ for illustration purposes).

[0151] In other words, compared to the positioning device 13 of system 1, the positioning device 13′ of system 1′ performs a displacement in a further direction (perpendicular to the first direction) rather than a rotation.

[0152] This modification of the system especially allows the assessment of the quality of non-cylindrical components, such as component 3′ which is of cubic shape in a beneficial manner.

[0153] System 1 and system 1′, both, might be either suitable for carrying out and/or configured to carry out, respectively, a method for assessing the quality of at least one component of optical material, such as component 3 or 3′, which has at least one first center axis. The method can be illustrated by means of reference to the systems 1 and 1′ as described before, although it is clear that also other setups than that described with respect to systems 1 and 1′ might be possible for carrying out the method.

[0154] The method comprises directing at least one light beam (such as light beam 11 or 11′ of system 1 or 1′) towards at least one detector device (such as detector device 7 or 7′ of system 1 or 1′) such that while changing the position and/or orientation of the component (such as component 3 or 3′ of system 1 or 1′) relative to the light beam, the light beam crosses at least from time to time the component and determining, by means of at least one determination device (such as determining device 15 or 15′ of system 1 or 1′), at least one characterizing value of at least one figure of merit of the component based on analyzing, by means of at least one analyzing device (such as analyzing device 15 or 15′ of system 1 or 1′), the dependency of one or more parameters of the light beam detected by the detector device on the position and/or orientation of the component.

[0155] When the light beam crosses the component, the light beam propagates through at least one thickness range of the component. For the cylindrical component of system 1 this thickness range is the shell of the component 3 and for the cubic component 3′ of system 1′ this thickness range is the thickness of the wall of the cubic.

[0156] For system 1 the optical element is located at least in part and/or at least from time to time within at least one volume enclosed by the component 3 when the method is carried out. This allows that the light beam always crosses the component, i.e. that at the detector side information of the component is always available.

[0157] FIG. 3 shows a diagram of the variation of a selected parameter for components of the same type but of different quality.

[0158] For example, the figure of merit (whose characterizing value might be desired to be determined with the system 1, the system 1′ and/or by carrying out the respective method as described above) might be directed to local deviation from a cylindrical design of a component of cylindrical shape (such as the component 3). In other words, the comparison of the cylindrical component to an ideal cylindrical shape is of interest.

[0159] For assessing this figure of merit, as parameter a first coordinate value of the position of the cross-section of the light beam within the detecting plane might be chosen.

[0160] The first coordinate value is on a first coordinate axis, wherein the first coordinate axis is along a third direction. The third direction is perpendicular to the first center axis of the component. For example, for the system 1 the third direction might be perpendicular to the drawing plane of FIG. 1.

[0161] FIG. 3 shows a diagram of the variation of the first coordinate value for cylindrical components A and B of two different qualities, which might preferably be obtained with a system such as system 1 described above in combination with FIG. 1. Here the parameter (first coordinate value) is detected by the detector device dependent on the rotation angle of the component, while the position of the component is at a fixed height. In other words, FIG. 3 shows the dependency of the first coordinate value (i.e. the parameter) of the light beam detected by the detector device on the orientation of, respectively, the components A and B.

[0162] Determining the characterizing value of the local deviation from a cylindrical design (i.e. the figure of merit) here comprises comparing the result obtained from analyzing the dependency in form of the variation of the parameter, against quantitative reference means. Here, the quantitative reference means comprise an upper threshold value (indicated in FIG. 3 by a solid horizontal line at 50 pixels) and a lower threshold value (indicated in FIG. 3 by a solid horizontal line at -50 pixels).

[0163] Thus, the result obtained from analyzing the dependency as shown in FIG. 3 is compared against the upper and lower threshold values. For example if the variation of the parameter exceeds the upper threshold value and/or falls below the lower threshold value, it is possible to classify the component's quality as not acceptable and otherwise as acceptable. In this regard, based on the results shown in FIG. 3, component A might be classified as not acceptable (because the parameter runs outside both thresholds) and component B might be classified as acceptable (because the parameter runs within both thresholds).

[0164] The features disclosed in the description, the figures as well as the claims could be essential alone or in every combination for the realization of the disclosure in its different embodiments.