Optical correction method for a light extraction system with a fixed angle of divergence from a laser

Abstract

The application discloses a light calibration method for a light taking system with a fixed included angle with a laser expander, which adopts a novel method to adjust the light taking system, so that the light taking system on the expander is coaxial with the laser in the case that the laser and the expander have a fixed included angle, and high-precision and precise adjustment of the light calibration of the telescope light taking system is realized. The light path structure is simple, and the operation is simple, so that the light calibration efficiency is greatly improved. The light calibration method is suitable for the optical axis calibration of the edge light taking device of the laser of each wavelength, and the wavelength range depends on the wavelength range of the beam analyzer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of telescope light taking optical system adjustment technology, and relates to a light calibration method for a light taking system with a fixed included angle between a laser and an expander, which is simple in structure and operation and suitable for light axis calibration of a light taking device for a laser edge. BACKGROUND

[0002] In the load of a spatial reflection type telescope optical system for laser height measurement and distance measurement, laser is favored due to its high brightness, good directivity, good monochromaticity, all-weather and other excellent characteristics, and has a wide application in the fields of aviation and aerospace.

[0003] For a satellite laser altimeter system, the time of initial laser pulse emission is crucial for subsequent distance calculation, and directly affects the measurement accuracy of the system. Therefore, how to accurately adjust the light taking position is a problem to be solved in the field of optical adjustment. In the actual adjustment process, the laser is fixed on the designed structure and cannot be ground, so there is always a certain included angle between the laser and the expander. Therefore, how to accurately take light under the condition that there is a certain included angle between the laser and the expander is very important. SUMMARY

[0004] The present application aims to provide a light calibration method for a light taking system with a fixed included angle between a laser and an expander. The present application introduces the optical axis of a light taking fiber into computer and laser registration based on a collimator and a corner cube prism. This method is suitable for the adjustment of a light taking system with high precision.

[0005] The detection device of the method of the present application is shown in FIG. 1. Figure 1 The device comprises a collimator (1), a transmitting-receiving coaxial device (2), a telescope expander system (3), a light taking fiber structure (4), a corner cube prism (5), a device laser (6), a 632.8 nm laser (7), a 1064 nm laser (8), an absorbing attenuator (9), a standard plane mirror (10), a Leica theodolite (11), and a cubic reference prism (12). The specific method steps are as follows:

[0006] 1. Calibration and assembly of the transmitting-receiving coaxial reference.

[0007] First, install the transceiver coaxial device 2 at the focal plane of the collimator 1, connect the 1064nm laser 8 to the light splitting prism 2-1, and place the corner cube prism 5 in front of the collimator 1. Turn on the laser, and the laser is split into two symmetrical beams by the light splitting prism. One of the beams is collimated by the collimator 1, reflected by the corner cube prism 5, and then converges to the photosensitive surface of the beam analyzer 2-2 through the collimator 1 to form an image. The shape of the imaging spot is observed on the computer. Second, place the corner cube prism 5 at different positions in front of the collimator 1, and observe whether the shape of the imaging spot of the corner cube prism 5 changes. Third, if the shape of the spot changes, adjust the distance between the transceiver coaxial device 2 and the collimator 1 until the shape of the spot does not change when the corner cube prism 5 is placed at different positions in front of the collimator 1. The position of the spot is the transceiver coaxial point, and the point is recorded using a computer. At this time, the calibration and assembly of the transceiver coaxial reference are completed.

[0008] 2. Laser optical axis alignment.

[0009] Place the device laser 6 in front of the collimator 1, and place an absorbing attenuator 9 between the device laser 6 and the collimator 1. Adjust the position of the device laser 6 so that the laser emitted by the device laser 6 converges on the transceiver coaxial point of the beam analyzer 2-2 through the collimator 1. At this time, the optical axis alignment of the device laser is completed, and the device laser 6 is fixed.

[0010] 3. Optical axis alignment of the telescope beam expansion system.

[0011] First, place the telescope beam expansion system 3 between the device laser 6 and the absorbing attenuator 9, turn on the device laser 6, and adjust the position of the telescope beam expansion system 3 so that the laser emitted by the device laser 6 converges on the transceiver coaxial point after passing through the telescope beam expansion system 3 and the collimator 1. Fix the telescope beam expansion system 3, turn off the laser, and remove the absorbing attenuator 9. Second, because there is a certain angle between the device laser 6 and the telescope beam expansion system 3, first place a standard plane mirror 10 on the platform where the telescope beam expansion system 3 is located. Use the Leica theodolite 11 to align the optical axis of the standard plane mirror 10 with the optical axis of the cubic reference prism 12. Then, adjust the platform where the standard plane mirror 10 is located to a certain angle relative to the actual position of the telescope beam expansion system 3. Fix the telescope beam expansion system 3. At this time, the optical axis alignment of the telescope beam expansion system 3 is completed.

[0012] 4. Optical axis alignment of the telescope light collection system.

[0013] Take away the absorption type attenuating sheet 9, install the light taking fiber structure 4, place the corner cube prism 5 at the laser light entrance of the telescope expansion system 3, connect the light taking fiber and the 632.8nm laser 7, open the laser, coarsely adjust the position of the light taking fiber structure 4, so that the light is incident on the light sensitive surface of the beam analyzer 2-2 through the telescope expansion system 3 and the collimator 1, then connect the light taking fiber and the 1064nm laser 8, open the laser, adjust the position of the light taking fiber structure 4, so that the light spot of the laser is at the position of the coaxial point of the receiving and transmitting marked in the foregoing, that is, the accurate registration of the optical axis of the telescope light taking system is completed.

[0014] The advantages of the present application mainly embody in the following aspects: (1) the calibration and assembly of the coaxial reference of the present application are simple and efficient; (2) the coaxial registration of the laser and the telescope expansion system is simple and has high accuracy; (3) the related systems involved in the present application are all reflective systems, and other laser systems of different wavelengths can also be applied, and the selection of the wavelength is mainly determined by the spectral wavelength range of the beam analyzer. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic diagram for the calibration and assembly of the coaxial reference of the present application;

[0016] Figure 2 It is a schematic diagram for the coaxial registration of the telescope light taking system of the present application;

[0017] Figure 3 It is a schematic diagram for the coaxial registration of the telescope expansion system of the present application;

[0018] Figure 4 It is a schematic diagram for the coaxial registration of the telescope light taking system of the present application. DETAILED DESCRIPTION

[0019] The implementation examples of the present patent method are described in detail below in combination with the drawings. The main components used in the present patent are described:

[0020] The collimator 1 is a common reflective collimator, the light aperture is 400mm, the focal length is 4000mm, the surface type of each mirror requires that the RMS is less than λ / 20 (λ=632.8nm), and the transmission surface of the collimator is coated with aluminum film.

[0021] The receiving and transmitting coaxial device 2 is composed of a beam splitter prism 2-1 and a beam analyzer 2-2; the beam splitter prism 2-1 has a beam splitting ratio of 5:5 for the used wavelength, and the surface RMS value of the light transmission surface is less than λ / 5 (λ=632.8nm).

[0022] 632.8nm); the beam analyzer 2-2 uses a beam analyzer of Model SP90421 of Spiricon Company, USA, and its main performance parameters are: working waveband 700nm-1100nm, pixel size 4.4um*4.4um, pixel number 1600*1200.

[0023] Telescope beam expander system 3: a 4.5 times reflection type beam expander system, and the surface type requirement is less than λ / 20 (632.8nm).

[0024] / 20 (632.8nm), and the primary and secondary mirrors are coated with Ag film.

[0025] Optical fiber structure 4: composed of an optical fiber, a turning mirror, a converging lens and corresponding structures, the optical fiber uses a single-mode optical fiber output, and its main performance parameters are: working wavelength 980-1600nm, optical fiber mode field diameter 6.2±0.3@1060nm, cladding core diameter 125±0.5um, cut-off wavelength 920±50nm; the converging lens is coated with an antireflection film, and the turning mirror is coated with an antireflection film.

[0026] Corner cube prism 5: uses a corner cube prism of Model PS976-M01B of Thorlabs Company, and its main performance parameters are: prism mirror coated with gold film, surface type less than λ / 10 (λ=632.8nm); rotation accuracy less than 3", clear aperture 50mm, and light transmission range 800-2000nm.

[0027] Device laser 6: the device laser is a self-developed 1064nm pulse laser, and its pulse energy is 180mj, working temperature 22±1.5℃, and energy stability better than 5%.

[0028] 632.8nm laser 7: uses a laser of Model MDL-III-633L of Changchun Xin Industry Optoelectronic Technology Co., Ltd., and its main performance parameters are: output power 1-80mW, spot mode TEM 00 , beam quality M 2 <1.5.

[0029] 1064nm laser 8: uses a laser of Model MIL-S-1064 of Changchun Xin Industry Optoelectronic Technology Co., Ltd., and its main performance parameters are: output power 1-1500mW, spot mode TEM 00 , beam quality M 2 <1.2.

[0030] Absorbing attenuator 9: the aperture of the absorbing attenuator is 200mm, and the transmittance is 15%.

[0031] Cubic reference prism 12: The reference prism is a regular cube reflection prism, which is a regular hexahedron with an angle error of 2 seconds between adjacent faces, and has three adjacent faces coated with a reflective film and a crosshair.

Claims

1. A method for collimating the light of a light-taking system at a fixed angle of divergence from a laser, the method using tools including a collimator (1), a coaxial transmitting and receiving device (2), a telescope divergence system (3), a light-taking system (4), a corner cube prism (5), a device laser (6), a 632.8 nm laser (7), a 1064 nm laser (8), an absorbing attenuator (9), a standard flat mirror (10), a Leica theodolite (11), and a cubic reference prism (12); characterized in that The method steps are as follows: Step one: the parallel light pipe (1) needs to be used with the transceiver coaxial device (2), the transceiver coaxial device (2) is placed near the focal plane of the parallel light pipe (1), the light sensitive surface of the light beam analyzer (2-2) in the transceiver coaxial device (2) is at the focal plane of the parallel light pipe (1); the light splitting prism (2-1) in the transceiver coaxial device (2) is connected with the 1064nm laser (8), the corner cube prism (5) is placed on the light outlet side of the parallel light pipe (1), the self-accurate function of the corner cube prism (5) is used, the light collimated by the parallel light pipe (1) is reflected by the corner cube prism (5), and then the light is converged to the light sensitive surface of the light beam analyzer (2-2) by the parallel light pipe (1) to form an image, and the position of the light spot of the light beam is marked as the transceiver coaxial point; Step two: the device laser (6) is placed on the light outlet side of the parallel light pipe (1), and the absorbing attenuating sheet (9) is placed between the device laser (6) and the parallel light pipe (1), the position of the device laser (6) is adjusted, the outgoing light of the laser is converged on the transceiver coaxial point by the parallel light pipe (1), and the device laser (6) is fixed; Step three: the telescope beam expansion system (3) is placed between the absorbing attenuating sheet (9) and the device laser (6), the device laser (6) is turned on, the position of the telescope beam expansion system (3) is adjusted, the outgoing light of the laser is converged to the transceiver coaxial point by the telescope beam expansion system (3) and the parallel light pipe (1), the telescope beam expansion system (3) is fixed, the laser is turned off, and the absorbing attenuating sheet (9) is removed; Step four: the light taking system (4) is installed on the telescope beam expansion system (3), because there is a certain angle between the device laser (6) and the telescope beam expansion system (3), a standard plane mirror (10) is first placed on the platform where the telescope beam expansion system (3) is located, the optical axis of the standard plane mirror (10) and the optical axis of the cubic reference prism (12) are unified by using the Leica theodolite (11), then the plane where the standard plane mirror (10) is located is adjusted to a certain angle to the actual position of the telescope beam expansion system (3); the light taking system (4) is installed, and the corner cube prism (5) is placed at the laser inlet of the telescope beam expansion system (3), the light taking fiber and the 632.8nm laser (7) are connected, the laser is turned on, the position of the light taking system (4) is coarsely adjusted, the light is incident on the light sensitive surface of the light beam analyzer (2-2) through the telescope beam expansion system (3) and the parallel light pipe (1), the light taking fiber and the 1064nm laser (8) are connected, the laser is turned on, the position of the light taking system (4) is adjusted, and the light spot is at the position of the transceiver coaxial point, so that the light taking system is light calibrated.

2. The method of claim 1, wherein the fixed angle is 90 degrees. The parallel light pipe (1) is a conventional parallel light pipe, the focal length is 4000mm, the mirror surface type RMS value is less than λ / 20, and λ=632.8nm.

3. The method of claim 1, wherein the laser beam is expanded by a fixed angle. The transceiving coaxial device (2) is composed of a light splitting prism (2-1) and a light beam analyzer (2-2); the light splitting ratio of the light splitting prism (2-1) for the wavelength is 5:5, the surface shape RMS value of the light passing surface is less than λ / 5, λ=632.8nm; the working wave band of the light beam analyzer (2-2) is 700nm to 1100nm.

4. The method of claim 1, wherein the laser beam is expanded by a factor of 2 to 10. The laser emitted by the device laser (6) is pulse laser, the wavelength is 1064nm, and the frequency is 1Hz.

5. The method of claim 1, wherein the laser beam is expanded by a fixed angle. The rotation precision of the corner cube prism (5) is less than 3", and the surface shape is less than λ / 10, λ=632.8nm.

6. The method of claim 1, wherein the laser beam is expanded by a factor of 2 to 10. The light taking system (4) is composed of optical fiber, folding mirror, converging lens and corresponding structure, wherein the optical fiber adopts single mode optical fiber output, the working wavelength is 980-1600nm; the converging lens is coated with antireflection film; the folding mirror is coated with antireflection film.

7. The method of claim 1, wherein the laser beam is expanded by a factor of 2 to 10. The output power of the 632.8nm laser (7) is 1-80mW.

8. The method of claim 1, wherein the laser beam is expanded by a factor of 2 to 10. The output power of the 1064nm laser (8) is 1-1500mW.

9. The method of claim 1, wherein the laser beam is expanded by a factor of 2.5 to 5.

0. The aperture of the absorption type attenuation sheet (9) is 200mm, and the transmittance is 15%.

10. The method of claim 1, wherein the laser beam is expanded by a factor of 2 to 10. The cubic reference prism (12) is a regular hexahedron, the angle error between adjacent surfaces is 2 seconds, and three adjacent surfaces are coated with reflective film and crosshair.

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