Laser beam directing system and method for orienting optical components of the laser beam directing system

Abstract

A laser beam directing system including a first deflection mirror which is connected with an elevation axis of the laser beam directing system; a primary laser which is coupleable into telescope optics by the first deflection mirror; a first auxiliary laser that is oriented in parallel to an azimuth rotation axis of the laser beam directing system; a second auxiliary laser that is oriented parallel to an elevation rotation axis of the laser beam directing system; and a first detector, wherein the first auxiliary laser, the second auxiliary laser and the first detector are arranged and oriented in the laser beam directing system so that the first deflection mirror is alignable by comparing beams of the first auxiliary laser and the second auxiliary laser impacting the first detector so that a beam from the primary laser is coupleable into the telescope optics parallel to the elevation rotation axis.

Claims

1. A laser beam directing system, comprising: a first deflection mirror which is attached at the laser beam directing system and moves with the laser beam directing system about an elevation axis of the laser beam directing system; telescope optics; a primary laser which is coupleable into the telescope optics by the first deflection mirror; a first auxiliary laser that is oriented in parallel to an azimuth rotation axis of the laser beam directing system; a second auxiliary laser that is oriented parallel to an elevation rotation axis of the laser beam directing system; a first detector, and a first beam splitter component, wherein the first auxiliary laser, the second auxiliary laser and the first detector are arranged and oriented in the laser beam directing system so that the first deflection mirror is alignable by comparing beams of the first auxiliary laser and the second auxiliary laser impacting the first detector so that a beam from the primary laser is coupleable into the telescope optics parallel to the elevation rotation axis, wherein the first beam splitter component is configured to decouple a first portion of the beams of the first auxiliary laser at a right angle onto the first detector and to let a second portion of the beams of the first auxiliary laser pass through.

2. The laser beam directing system according to claim 1, wherein the first deflection mirror has a dielectric coating, and wherein the dielectric coating is configured so that the first deflection mirror is reflective for the primary laser and partiaily reflective for the auxiliary lasers.

3. The laser beam directing system according to claim 1, wherein the primary laser has a first wavelength, wherein the first auxiliary laser has a second wavelength, wherein the second auxiliary laser has a third wavelength, and wherein the first wavelength differs from the second wavelength and from the third wavelength.

4. The laser beam directing system according to claim 1, wherein an adjustment element is provided at the first deflection mirror, and wherein the adjustment element is configured to adjust an inclination angle or an orientation of the first deflection mirror in the azimuth rotation axis and in the elevation rotation axis.

5. The laser beam directing system according to claim 4, wherein the adjustment element is configured as a piezo motor.

6. The laser beam directing system according to claim 1, wherein the first auxiliary laser is operable simultaneously or time sequentially with the second auxiliary laser.

7. The laser beam directing system according to claim 1, further comprising; a control unit, wherein the control unit is configured to determine a first angle of incidence of a beam from the first auxiliary laser on the first detector and a second angle of incidence of a beam from the second auxiliary laser on the first detector, and wherein the control unit is configured to adjust the first deflection mirror so that the first angle of incidence is identical to the second angle of incidence.

8. The laser beam directing system according to claim 1, further comprising: a first beam splitter component, wherein the first beam splitter component is configured to decouple a first portion of the beam from the first auxiliary laser at a right angle onto the first detector and to let a second portion of the beam from first auxiliary laser pass through, and wherein the first beam splitter component is configured to decouple a first portion of the beam from the second auxiliary laser at a right angle onto the first detector.

9. The laser beam directing system according to claim 8, further comprising: a first coplanar plate which is arranged physically fixated in the azimuth rotation axis of the laser beam directing system, wherein the first coplanar plate is configured partially reflective for the first auxiliary laser and for the second auxiliary laser, and wherein an orientation of the first auxiliary laser parallel to the azimuth rotation axis of the laser beam directing system is adjustable by the first coplanar plate, the first beam splitter component and the first detector.

10. The laser beam directing system according to claim 9, further comprising: a first aperture, wherein the first aperture is configured to close the first coplanar plate.

11. The laser beam directing system according to claim 1, further comprising: a second detector, wherein the second detector is arranged in the laser beam directing system so that the first deflection mirror is alignable by comparing beams from the first auxiliary laser and the second auxiliary laser impacting the second detector so that a beam from the primary laser is coupleable into the telescope optics parallel to the elevation rotation axis.

12. The laser beam directing system according to claim 1, further comprising: a second deflection mirror; a third deflection mirror; and a fourth deflection mirror, wherein the second deflection mirror, the third deflection mirror and the fourth deflection mirror are mounted at an azimuth rotation yoke of the laser beam directing system, and wherein the first auxiliary laser, the second auxiliary laser and the first detector are arranged in the laser beam directing system so that the second deflection mirror, the third deflection mirror and the fourth deflection mirror are alignabie by comparing the beams from the first auxiliary laser and the second auxiliary laser impacting the first detector so that a beam from the primary laser extends parallel to the azimuth rotation axis and parallel to the elevation rotation axis in the laser beam directing system.

13. A method for orienting the first deflection mirror, a second deflection mirror, a third deflection mirror and a fourth deflection mirror of the laser beam directing system according to claim 1, comprising the steps: operating the first auxiliary laser which is aligned parallel to the azimuth rotation axis of the laser beam directing system; operating the second auxiliary laser which is aligned parallel to the elevation rotation axis of the laser beam directing system; determining a first angle of incidence of a beam rom the first auxiliary laser on the first detector; determining a second angle of incidence of a beam from the second auxiliary laser on the first detector; and adjusting the first deflection mirror, the second deflection mirror, the third deflection mirror and the fourth deflection mirror of the laser beam directing system so that the first angle of incidence is identical with the second angle of incidence.

14. The method according to claim 13, wherein adjusting or readjusting the first deflection mirror, the second deflection mirror, the third deflection mirror and the fourth deflection mirror is performed dynamically.

15. The method according to claim 13, further comprising the steps: aligning the first auxiliary laser parallel to the azimuth rotation axis of the laser beam directing system; and aligning the second auxiliary aser parallel to the elevation rotation axis of the laser beam directing system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are subsequently described with reference to the drawing figures, wherein:

(2) FIG. 1 illustrates a schematic of a laser beam directing system according to the invention;

(3) FIG. 2 illustrates a cross section of laser beam directing system according to an embodiment of the invention; and

(4) FIG. 3 illustrates a flow chart of a method for orienting optical components of a laser beam directing system according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) All figures are mere representations of devices according to the invention or their components according to embodiments of the invention. In particular distances and size relationships in the figures are not represented according to scale. In different figures equivalent elements are provided with identical reference numerals.

(6) FIG. 1 illustrates a laser beam directing system for quickly directing a primary laser beam at a target which can move in an entire hemisphere. The primary laser beam is introduced by mirrors that are not visible in FIG. 1 into the Coudéoptical channel. In the Coudéoptical channel 11 the primary laser beam is routed by a fourth deflection mirror 29, a third deflection mirror 27 and a second deflection mirror 25 to telescope optics 12. The primary laser beam is coupled into the telescope optics 12 by a first deflection mirror 23 which is not visible in FIG. 1. In the telescope optics 12, the primary laser beam is expanded and focused.

(7) Using the laser beam directing system 1, the primary laser can be track a moving target. For this purpose the laser beam directing system 1 includes an azimuth rotation yoke 3 which is supported in an azimuth bearing 5 and rotatable about an azimuth axis by means of an azimuth motor 9. Furthermore the laser beam directing system 1 includes an elevation support 7 at which the telescope optics 12 are rotatable about an elevation axis by means of an elevation motor 10.

(8) A precise adjustment of the deflection mirrors 23, 25, 27, 29 is required in order to provide a highly precise alignment of the primary laser beam with the target. It is particularly advantageous when the primary laser beam extends parallel to the rotation axes of the laser beam directing system 1. The highly precise alignment is provided through the configuration of the laser beam directing system 1 with auxiliary lasers 19, 21 and detectors 15, 17. This will be described in more detail with reference to FIG. 2. Thus the configuration of the laser beam directing system 1 according to the invention facilitates a dynamic readjustment of the deflection mirrors 23, 25, 27 and 29 so that a precise laser directing is also provided over longer time periods and for a moving laser directing system 1, thus under dynamic loads. Thus, the deflection mirrors 23, 25, 27 and 29 can be aligned with a precision of a few micro rad relative to the two rotation axes of the laser beam directing system 1.

(9) FIG. 2 illustrates a cross section of a so called Altazimuth beam directing unit with an axis of the telescope optics 12 which axis is aligned parallel to the azimuth axis. The primary laser beam of the primary laser 13 is coupled in parallel to the azimuth axis into the directing unit or in the laser beam directing system by a mirror 47 that is fixated in position. The primary laser beam is coupled into the optical axis of the telescope optics by the deflection mirrors mounted in the azimuth rotation yoke 3 or in the Coudéoptical channel 11, namely the second deflection mirror 25, the third deflection mirror 27 and the fourth deflection mirror 29 within the laser beam directing system 1 parallel to the elevation axis by the first deflection mirror 23 which is moved together with the elevation axis.

(10) A first auxiliary laser 19 and a second auxiliary laser 21 are used as tools for adjusting the deflection mirrors 23, 25, 27 and 29. The beam of the first auxiliary laser 19 is radiated into the laser beam directing system 1 collinear with the azimuth rotation axis and the beam of the second auxiliary laser 21 collinear with the elevation rotation axis. The wavelengths of the auxiliary lasers 19, 21 differ from the wavelength of the primary laser 13 to be directed. The wavelength of the first auxiliary laser can be for example 532 nm, the wavelength of the second auxiliary laser can be for example 635 nm and the wavelength of the primary laser can be for example 1070 nm.

(11) The optical components, in particular the first deflection mirror 23, the second deflection mirror 25, the fourth deflection mirror 29 and the fixated mirror 47 can be configured as coplanar plates. The material of the coplanar plates can thus be transparent for the wavelengths of the auxiliary lasers 19, 21. The front sides of these mirrors, this means the sides of the mirrors that are oriented towards the primary laser beam can be coated so that they are highly reflective for the primary laser radiation and partially reflective for the radiation of the auxiliary lasers. The third deflection mirror 27 can be coated with metal.

(12) A first coplanar plate 35 is arranged in the azimuth rotation axis perpendicular thereto and fixated at the azimuth rotation yoke 3. The material of the first coplanar plate 35 is transparent for the wavelengths of the auxiliary lasers 19, 21. Furthermore the surface of the first coplanar plate 35 is provided with a coating that is partially reflective for the auxiliary laser radiation. A first aperture 39 is arranged in front of the first coplanar plate 35 in particular between the first auxiliary laser 19 and the first coplanar plate 35. The first aperture 39 is thus configured to prevent a transmission and also a reflection of the first auxiliary laser beam at the first coplanar plate 35 in a closed condition of the first aperture 39. The first aperture 39 can be opened and closed at will.

(13) In the same way a second coplanar plate 37 is arranged in the elevation rotation axis perpendicular thereto and fixated at the support 7 of the telescope optics 12. The second coplanar plate 37 is thus configured as a planar mirror. A second aperture 41 is arranged in front of the second coplanar plate 37. The second aperture 41 prevents a reflection of the first and the second auxiliary laser beam at the second coplanar plate 37 in a closed condition of the second aperture 41. Thus, the second aperture 41 can be opened and closed at will.

(14) The first auxiliary laser 19 is mounted fixated in place. The second auxiliary laser 21 is fixated in the azimuth yoke 3. Initially an alignment of the auxiliary lasers 19, 21 parallel to the axes can be checked and adjusted as required before starting the primary laser 13 or the laser beam directing system 1.

(15) For this purpose the first auxiliary laser 19 is aligned to the first coplanar plate 35 while transmitting through the spatially fixated mirror 47 and the fourth deflection mirror 29 with the first aperture 39 open. In order to check the alignment a first beam splitter component 31 and the first detector 15 are used wherein the first beam splitter component is arranged downstream of the first auxiliary laser 19 and configured as a beam splitter cube.

(16) The first beam splitter component 31 is thus provided so that its diagonal mirror surface couples out a few percent of the beam of the first auxiliary laser 19 at a right angle onto the first detector 15. The transmitted beam of the first auxiliary laser 19 is reflected back into itself by the first coplanar plate 35 and also coupled out onto the first detector 15 by the diagonal mirror surface and a mirrored surface of the first beam splitter component 31. The first detector 15 is configured, for example, as a Hartmann-Shack sensor. Thus, the first detector 15 can determine the respective tilting of the two received beams. The alignment or angular adjustment of the first auxiliary laser 19 can now be provided so that the tilting of the two beams received at the first detector 15 is identical.

(17) The second auxiliary laser 21 can be aligned similar to the first auxiliary laser 19. The beam of the second auxiliary laser 21 is aligned perpendicular to the second coplanar plate 37 while transmitting through the second deflection mirror 25 and the first deflection mirror 23 with the second aperture 41 open. In order to check alignment a second beam splitter component 33 arranged after the second auxiliary laser 21 in its beam path and the second detector 17 are used.

(18) The second beam splitter component 33 is configured similar to the first beam splitter component 31 and configured so that its diagonal mirror surface couples a few percent of the beam of the second auxiliary laser 21 out at a right angle onto the second detector 17. The portion of the second auxiliary laser beam transmitted through the second beam splitter component 33 is reflected back into its self by the second coplanar plate 37 and also coupled out onto the second detector 17 through a diagonal mirror surface and a mirrored surface of the second beam splitter component 33. The second detector 17 can thus be also configured as a Hartmann-Shack sensor. Using the second detector 17 the tilts of the two received beams can be determined. The alignment or angular adjustment of the second auxiliary laser 21 can now be performed so that the tilting of the two beams received at the second detector 17 is identical.

(19) The described adjustment of the first auxiliary laser 19 and the second auxiliary laser 21 assures that the first auxiliary laser 19 is aligned with very high precision parallel to the azimuth rotation axis and the second auxiliary laser 21 is aligned with very high precision parallel to the elevation rotation axis. Using the laser beams of the auxiliary laser 19, 21 thus adjusted an adjustment of the deflection mirrors 23, 25, 27 and 29 can be performed thereafter.

(20) For example, the first deflection mirror 23 can be adjusted or aligned by means of the auxiliary lasers 19, 21 as follows: the first deflection mirror 23 is adjusted so that the beam of the second auxiliary laser 21 reflected by the second coplanar plate 37 and the first deflection mirror 23 impacts the first detector 15 at the same angle as the beam of the first auxiliary laser 19 coupled out by the first beam splitter component 31. For control purposes the first deflection mirror 23 can be additionally simultaneously aligned so that the beam of the first auxiliary laser 19 reflected by the first reflection mirror 23 and the second coplanar plate 37 impacts the second detector 17 at the same angle as the beam of the second auxiliary laser 21 that is coupled out by the second beam splitter component 33.

(21) Also the additional deflection mirrors 25, 27, 29 can be controlled and adjusted similar to the first deflection mirror 23. In particular the deflection mirrors 25, 27, 29 can be iteratively adjusted so that the beam of the first auxiliary laser reflected by the fourth mirror 29, the third deflection mirror 27, the second deflection mirror 25, the second coplanar plate 37 and the second beam splitter component 33 centrally impacts the second detector 17. Thus, the deflection mirrors 25, 27, 29 are furthermore iteratively readjusted so that the beam of the first auxiliary laser 19 impacts the second detector 17 at the same angle as the beam of the second auxiliary laser 21 reflected by the second beam splitter component 33.

(22) For control purposes and in order to improve precision of alignment the deflection mirrors 25, 27, 29 can be furthermore adjusted so that the beam of the second auxiliary laser 21 reflected by the second coplanar plate 33, the second deflection mirror 25, the third deflection mirror 27, the fourth deflection mirror 29 and the first beam splitter component 31 centrally impacts the first detector 15. Thus the deflection mirrors 25, 27, 29 are furthermore iteratively readjusted so that the beam of the auxiliary laser 21 impacts the first detector 15 at the same angle as the beam of the first auxiliary laser 19 reflected by the first beam splitter component 21.

(23) If required for differentiating the individual auxiliary lasers 19, 21, the auxiliary lasers 19, 21 can be turned on and off in a time sequential manner and the coplanar plates 35, 37 can be covered by the apertures 39, 41.

(24) The adjustment can be performed in a static manner before starting up the primary laser 13 or the laser beam directing system 1. Alternatively the adjustment can be performed during operation of the laser beam directing system and in particular of the primary laser 13. Thus, deviations of the alignment that are caused by operational dynamic forces can be measured and corrected. The optical compensation of the deviations can be provided by motor driven adjustment elements 43. Thus two respective adjustment elements 43 can be provided at each deflection mirror 23, 25, 27, 29 wherein the adjustment elements are configured for example as piezo elements.

(25) The adjustment elements 43 can be connected with a control unit 45. The control unit 45 can be furthermore connected with the first detector 15 and the second detector 17. Based on the data read out at the detectors 15, 17 the control unit 45 can control the control elements 43 and can readjust the deflection mirrors 23, 25, 27, 29 in this manner.

(26) An additional control of an angular position of the first deflection mirror 23 can be provided during operations of the laser beam directing system 1 when an additional beam splitter element is provided on a backside of the deflection mirror 23, wherein the additional beam splitter element causes a partial deflection of the transmitted beams of the first auxiliary laser 19 and/or the second auxiliary laser 21 at a slant angle of for example 30°. This can be provided for example by an optical diffraction grating integrated on a back side of the first deflection mirror 23.

(27) An angle of beams of the first auxiliary laser 19 and/or the second auxiliary laser 21 deflected in this manner can be measured by the third detector 49 provided in the wall of the telescope optics 12. A suitable correction of an angular deviation can be performed using the measuring data of the first detector 15 and the second detector 17 using the adjustment elements 43 at the deflection mirrors 23, 25, 27, 29.

(28) FIG. 3 illustrates a flow chart of an embodiment of a method for aligning optical components, in particular, the deflection mirrors 23, 25, 27, 29 of the laser beam directing system 1. The method can be supplemented at will by additional steps which were recited, for example, with respect to FIG. 2.

(29) In a first step S01, the first auxiliary laser 19 as described in conjunction with FIG. 2 is aligned in parallel with the azimuth rotation axis of the laser beam directing system 1. Furthermore, the second auxiliary laser 21 is aligned in step S03 in parallel with the elevation rotation axis of the laser beam directing system 1. Subsequently the auxiliary lasers 19, 21 are radiated into the laser beam directing system in parallel to the axes. This is performed in steps S05 and S07.

(30) In step S09 a first angle of incidence of the first auxiliary laser beam on a first detector 15 is determined. In step S11 a second angle of incidence of the second auxiliary laser beam on the first detector 15 is determined. Subsequently the optical components 23, 25, 27, 29 like, for example, the first deflection mirror 23 are adjusted in step S13 so that the first angle of incidence coincides with the second angle of incidence.

(31) The steps of the method can thus be partially performed in an alternating sequence or in parallel with one another. For example the first auxiliary laser 19 and the second auxiliary laser 21 can be operated simultaneously. This means the steps S05 and S07 can be performed in parallel with one another. Furthermore the steps S09 and S11 can be performed in parallel with one another or sequentially.

(32) It is appreciated that features of the embodiments and aspects of the device also are applicable for embodiments of the method and vice versa. Furthermore features can be freely combined with one another unless explicitly stated to the contrary.

(33) In closing it is appreciated that terms like “comprising” or similar do not exclude additional elements or steps from being provided. Furthermore it is appreciated that the term “a” does not exclude a plurality. Furthermore features described in a context with various embodiments can be combined with one another at will. It is furthermore appreciated that the reference numerals in the patent claims shall not limit the scope of the patent claims.

REFERENCE NUMERALS AND DESIGNATIONS

(34) 1 laser beam directing system

(35) 3 azimuth rotation yoke

(36) 5 azimuth axis support

(37) 7 elevation axis support

(38) 9 azimuth motor

(39) 10 elevation motor

(40) 11 Coudéoptical channel

(41) 12 telescope optics

(42) 13 primary laser

(43) 15 first detector

(44) 17 second detector

(45) 19 first auxiliary laser

(46) 21 second auxiliary laser

(47) 23 first deflection mirror

(48) 25 second deflection mirror

(49) 27 third deflection mirror

(50) 29 fourth deflection mirror

(51) 31 first beam splitter component

(52) 33 second beam splitter component

(53) 35 first coplanar plate

(54) 37 second coplanar plate

(55) 39 first aperture

(56) 41 second aperture

(57) 43 adjustment element

(58) 45 control unit

(59) 47 mirror spatially fixated

(60) 49 third detector

(61) S01 aligning the first auxiliary laser parallel to the azimuth rotation axis of the laser beam directing system

(62) S03 aligning the second auxiliary laser parallel to the elevation rotation axis of the laser beam directing system

(63) S05 operating the first auxiliary laser

(64) S07 operating the second auxiliary laser

(65) S09 determining a first angle of incidence of the first auxiliary laser beam on a first detector

(66) S11 determining a second angle of incidence of the second auxiliary laser beam on the first detector

(67) S13 adjusting the optical components of the laser directing system so that the first angle of incidence coincides with the second angle of incidence.