A jitter compensation device and method for high-precision pointing system

Abstract

The present invention discloses a jitter compensation device and method for a high-precision pointing system, which belongs to the field of adaptive optics. The method constructs a proprietary optical device, uses a high-power microscope system to perform jitter analysis on the autocollimated image reflected from the product end, and then drives the rapid rotation of the two-dimensional reflector, thereby realizing jitter compensation of the entire system. The method involved in the present invention can achieve a jitter compensation accuracy better than 0.1″ and a resolution better than 0.01″, thereby providing high-precision test conditions for high-precision sensors.

Description

Technical Field

[0001] The invention relates to a jitter compensation device and method for a high-precision pointing system, and belongs to the field of adaptive optics. Background Art

[0002] Traditionally, the accuracy test of pointing sensors conducted on the ground can measure a limit level of 1″. For higher accuracy and higher tests, the influencing factors include air disturbance, ground jitter, and specific random jitter of motor-controlled components inside the equipment. Air disturbance can be eliminated by installing the entire set of equipment in a confined space and controlling the airflow in the confined space. Ground jitter can be eliminated to a certain extent through the foundation, but usually the highest level is E level. The jitter inside the equipment can only be reduced to a certain extent but cannot be eliminated. Taking various control measures and using traditional methods to conduct ground accuracy tests cannot achieve higher accuracy pointing sensor accuracy tests. Summary of the invention

[0003] The purpose of the present invention is to overcome the jitter problem of the traditional precision test system and provide a high-stability simulation system that can realize sensor testing with milli-arcsecond level precision.

[0004] The technical solution of the present invention is:

[0005] A jitter compensation device for a high-precision pointing system, comprising: an adjustable color temperature light source (1), a graticule (2), an adjustable aperture (3), a light source collimation system (4), a beam splitting system (5), a neutral attenuation plate (6), a reflector (7), a jitter compensation system (11), a signal light beam expansion system (12), a reference light beam expansion system (8), a microscopic imaging system (9), a detector (10), a sensor (13) and a mounting bracket (14) thereof;

[0006] The adjustable color temperature light source (1) emits quasi-monochromatic light and composite light of different color temperatures to illuminate the differentiation plate (2), which is collimated into quasi-parallel light by a light source collimation system (4), and then split into a reference beam and a test beam by a beam splitting system (5), wherein the reference beam propagates toward a neutral attenuation plate (6), and the test beam propagates toward a jitter compensation system (11). An adjustable aperture (3) is provided between the differentiation plate (2) and the light source collimation system (4) to control the amount of light passing through and suppress stray light.

[0007] The reference beam first passes through a neutral attenuation plate (6) for a first energy attenuation, then passes through a reflector (7) and then passes through the neutral attenuation plate (6) for a second energy attenuation. The beam after the second energy attenuation is split by a beam splitting system (5) to form a second reference beam and a third reference beam. The second reference beam propagates toward a reference light beam expansion system (8), and the third reference beam propagates toward a light source collimation system (4). The third reference beam is a non-working beam and is absorbed by the structure. After the second reference beam is expanded, it is directly imaged by a microscopic imaging system (9) and received by a detector (10).

[0008] The test beam passes through a jitter compensation system (11) and a signal light beam expansion system (12) and finally reaches the focal plane of a sensor (13). A reflector is arranged at the entrance of the secondary mirror of the sensor. A part of the test beam is reflected by the reflector back to the signal light beam expansion system (12) and then propagates to the beam splitting system (5) through the jitter compensation system (11) to form a second test beam and a third test beam. The third test beam propagates toward the light source collimation system (4). The third test beam is a non-working beam and is absorbed by the structure. The second test beam propagates toward the reference light beam expansion system (8), is expanded by the beam expansion system and amplified by the microscope system, and is also received by the detector (10).

[0009] Furthermore, the adjustable color temperature light source (1) uses an LED as a light source, emitting quasi-monochromatic light and composite light of different color temperatures, and the energy of the emitted light meets the sensitivity requirement of the pointing measurement sensor (13) for stars being sensitive in the range of 0Mv to 10Mv; the spectral range of the adjustable color temperature light source (1) is the full spectrum of 400nm to 900nm.

[0010] Furthermore, the graticule (2) is processed by mask etching. The types of star points distributed on the graticule include stars in a specific sky area and array star points. The distributed star points have different calibers. In order to ensure the intensity of the signal light return energy, the diameter of the central star point is designed to be 400 microns, and the peripheral star points are etched by equating the star point diameter with the relationship between the magnitudes of different star points.

[0011] Furthermore, the light source collimation system (4) performs aberration elimination processing on the entire spectrum to ensure that the size of the diffuse spot is smaller than the minimum star point diameter of the graticule.

[0012] Furthermore, the splitting ratio of the light splitting system (5) is controlled to be 50%:50%, and the collimated light beam is split.

[0013] Furthermore, the neutral attenuation plate (6) attenuates the energy of the reference light beam to ensure that the energy difference between the light spot of the second test light beam and the light spot of the second reference light beam is within 10%. The neutral attenuation plate (6) also limits the aperture of the reference light beam.

[0014] The angle between the reflector (7) and the optical axis is 90.2°, so that the pixel spacing between the second reference light return light spot and the second test light beam return light spot is greater than 50 pixels.

[0015] Furthermore, the jitter compensation reflector (11) can rotate around two axes to adjust the direction of the emitted light. The jitter frequency of the jitter compensation reflector (11) is greater than 500 Hz. PID is used to control the swing of the jitter compensation reflector to achieve compensation for environmental jitter not greater than 100 Hz. The two axes are respectively a pitch axis and a yaw axis.

[0016] Furthermore, the signal light beam expansion system (12) is a telescopic system that expands a 30 mm light beam to 200 mm. The signal light beam expansion system (12) adopts a two-reflection design, wherein the primary mirror is a positive axis parabola and the secondary mirror is a positive axis hyperboloid.

[0017] The sensor (13) is a star sensor to be measured, and the mounting bracket (14) is used for mounting the sensor (13);

[0018] The reference light beam expansion system (8) includes two stages of beam expansion. The beam expansion process is to first expand the 3.2 mm beam into 40 mm, and then expand the 40 mm beam to 400 mm. The first stage of beam expansion adopts the structure of a transmission telescope system, and the second stage of beam expansion adopts a two-reflection design with a beam expansion ratio of 12.5 times. The primary and secondary mirrors are designed as positive axis parabolic mirrors, and both the primary and secondary mirrors are made of microcrystalline glass.

[0019] Furthermore, the microscopic imaging system (9) amplifies the reference light and the signal light to form an image. The microscopic imaging system (9) adopts a two-reflector design to converge the obtained 400 mm light beam, with a focal length of 5000 mm. The primary mirror is a positive axis parabola, and the secondary mirror is a positive axis hyperboloid.

[0020] The detection imaging system (10) is capable of detecting light energy reflected back at 10 Mv and achieving star point extraction greater than 500 Hz.

[0021] Furthermore, the present invention also proposes a jitter compensation method, the steps of which are as follows:

[0022] Step 1: The microscopic imaging system extracts the centroid of the two detected light spots;

[0023] Step 2: The center of mass obtained by the second test beam is returned and compared with the case without jitter compensation to confirm the offset. If there is an offset, the pitch and yaw axes of the jitter compensation mirror are driven to compensate.

[0024] Step three: re-determine the offset of the light spot formed by the second test beam and the second reference beam through the microscopic imaging system, and repeat steps two and three until there is no offset of the light spot formed by the second test beam and the second reference beam. After the jitter compensation is completed, monitor the next moment.

[0025] The advantages of the present invention compared with the prior art are:

[0026] The calibration device of the present invention compares and judges the signal light and the reference light, and compensates by rapidly swinging the two axes of the jitter compensation reflector, thereby obtaining a stable light beam at the signal end, and providing highly stable star light for the accuracy test of high-precision or ultra-high-precision sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the composition of the calibration device of the present invention;

[0028] Figure 2 This is a flowchart of the jitter compensation process of the present invention. DETAILED DESCRIPTION

[0029] The present invention uses collimated light source beams to split them into reference light and signal light. The signal light is reflected by a reflector on the front end of the sensor. The pitch and yaw of the jitter compensation reflector are controlled by calculating the signal light and the reference light, thereby ensuring the high stability of the emitted light and providing star points for the accuracy test of the high-precision sensor.

[0030] The whole set of jitter compensation device of the present invention is composed of the following components: Figure 1 As shown, it includes an adjustable color temperature light source 1, a graticule 2, an adjustable aperture 3, a light source collimation system 4, a beam splitting system 5, a neutral attenuation plate 6, a reflector 7, a jitter compensation system 11, a signal light beam expansion system 12, a reference light beam expansion system 8, a microscopic imaging system 9, a detector 10, a sensor 13 and its mounting bracket 14.

[0031] The color temperature adjustable light source 1 emits quasi-monochromatic light and composite light of different color temperatures, illuminates the differentiation plate 2, is collimated into quasi-parallel light by the light source collimation system 4, and is split into a reference beam and a test beam by the beam splitting system 5, wherein the reference beam propagates toward the neutral attenuation plate 6, and the test beam propagates toward the jitter compensation system 11. An adjustable aperture 3 is provided between the differentiation plate 2 and the light source collimation system 4, for controlling the amount of light passing through and suppressing stray light;

[0032] The reference beam first passes through the neutral attenuation plate 6 for the first energy attenuation, and then passes through the neutral attenuation plate 6 again for the second energy attenuation after being reflected by the reflector 7. The beam after the second energy attenuation is split by the beam splitting system 5 to form a second reference beam and a third reference beam, wherein the second reference beam propagates toward the reference light beam expansion system 8, and the third reference beam propagates toward the light source collimation system 4. The third reference beam is a non-working beam and is absorbed by the structure. After the second reference beam is expanded, it is directly imaged by the microscopic imaging system 9 and received by the detector 10.

[0033] The test beam passes through the jitter compensation system 11 and the signal light beam expansion system 12, and finally reaches the focal plane of the sensor 13. A reflector is set at the entrance of the secondary mirror of the sensor. A part of the test beam is reflected back to the signal light beam expansion system 12 by the reflector, and then propagates to the beam splitting system 5 through the jitter compensation system 11 to form a second test beam and a third test beam, wherein the third test beam propagates toward the light source collimation system 4. The third test beam is a non-working beam and is absorbed by the structure. The second test beam propagates toward the reference light beam expansion system 8, is expanded by the beam expansion system and amplified by the microscope system, and is also received by the detector 10.

[0034] The adjustable color temperature light source 1 uses LED as a light source, which can emit quasi-monochromatic light and composite light of different color temperatures, such as 6000K color temperature. The energy of the emitted light can meet the sensitivity requirement of the pointing measurement sensor 13 to the star sensitivity range of 0Mv~10Mv. The spectral range of the adjustable color temperature light source 1 is the full spectrum of 400nm~900nm.

[0035] The graticule 2 is processed by mask etching. The types of star points distributed on the graticule include stars in specific sky areas and array star points. The distributed star points have different calibers. In order to ensure the intensity of the signal light return energy, the diameter of the central star point is designed to be as large as 400 microns. The outer star points are etched according to the relationship between the different star point magnitudes and the equivalent star point diameter.

[0036] A 20mm reflector is placed at the center of the sensor to reflect the jitter signal to be measured. After returning to the detection branch, the jitter signal light aperture is reduced to 3.2mm. The vibration signal beam needs to be expanded to an acceptable range. According to the magnitude requirement, the beam received by the sensor is very weak, and the beam returned is even weaker due to the limited aperture. This factor should be fully considered, and the frame rate should be taken into account to select a suitable CCD to meet the requirements. In order to achieve a compensation accuracy of 0.1", the compensation resolution reaches 0.01". Use the centroid compensation algorithm for star point positioning. When the vibration signal beam is offset, the CCD pixel corresponds to 0.1". The detection star point signal occupies between 3 and 8 pixels of the CCD, thereby ensuring the detection accuracy.

[0037] The luminous flux input from the sensor reflector end to the detection system is ф1. Since the simulation of 10th magnitude stars is the limit detection condition of the system, the corresponding illumination value is 2.67×10 -10 lx, the relationship between the illumination at the exit of the collimator and the star point is as follows:

[0038]

[0039] When the 40μm star point simulates 10Mv, the illumination value corresponding to 40μm at the light outlet of the collimator is 2.67×10 -10 lx, 400μm corresponds to an illuminance value of 2.67×10-8 lx, based on this illumination value, the illumination value reflected back to the detector system is calculated to determine the final camera.

[0040] The adjustable aperture 3 can effectively control the amount of light entering the system and suppress stray light.

[0041] The light source collimation system 4 has a designed working spectrum of 400nm to 900nm, adopts a transmission structure, has a designed field of view of 2ω=12.6°, and a designed entrance pupil of 30mm, which means that after the light source beam passes through the collimation system, the beam diameter is 30mm.

[0042] The light source collimation system performs achromatic treatment on the entire spectrum to ensure that the size of the diffuse spot is smaller than the minimum star point diameter of the graticule. In the present invention, the diffuse spot is controlled within 22 microns.

[0043] The beam splitting system 5 splits the collimated light beam into two beams, and within the designed spectral range of 400nm to 900nm, the energy of the two beams each accounts for 50%.

[0044] The neutral attenuation plate 6 attenuates the energy of the reference light to ensure that the energy difference between the final signal light spot and the reference light spot is within 10%. In addition, the aperture of the reference light is limited to about 3.2 mm.

[0045] The reflector 7 has an angle of 90.2° with the optical axis, ensuring that under ideal conditions, the pixel spacing between the reference light return light spot and the signal light return light spot is greater than 50 pixels, thereby ensuring the extraction accuracy of the two light spots.

[0046] The jitter compensation system 11 can rotate around two axes and adjust the direction of the outgoing light. In order to ensure that the final compensation frequency is greater than 100 Hz, the jitter frequency of the jitter compensation mirror is greater than 500 Hz, wherein the two axes of jitter compensation are the pitch axis and the yaw axis.

[0047] The signal light beam expansion system 12 is a telescopic system that can expand a 30mm light beam to 200mm. The beam expansion system adopts a two-reflection system. The primary mirror is designed as a positive axis parabola, and the secondary mirror adopts a positive axis hyperboloid design. Since it is a reflective system, there is no need to consider the influence of chromatic aberration.

[0048] The sensor 13 is a sensor to be measured, mainly a high-precision star sensor, such as an ultra-high-precision star sensor or a milli-arcsecond star sensor, etc. The mounting bracket 14 is used for mounting the sensor.

[0049] Reference light beam expansion system 8 includes two-stage beam expansion. The beam expansion process is to first expand 3.2mm to 40mm, and then expand the 40mm beam to 400mm. The first-stage beam expansion adopts the structure of the traditional transmission telescope system. The second-stage beam expansion system adopts a two-reflection design with a beam expansion ratio of 12.5 times. The primary and secondary mirrors are designed as positive axis parabolic mirrors. The reflection system does not need to consider the influence of chromatic aberration. Both the primary and secondary mirrors are made of microcrystalline glass. This system is an ideal beam expansion system. The wave aberration introduced within the range of ±0.5' is very small, resulting in negligible star point distortion.

[0050] The microscopic imaging system 9 converges the obtained 400mm light beam. The convergence system also adopts a two-reflection design with a focal length of 5000mm. The primary mirror is designed as a positive axis parabola, and the secondary mirror adopts a positive axis hyperboloid design. Since it is a reflection system, the influence of chromatic aberration does not need to be considered.

[0051] The detection imaging system 10 has high sensitivity, can detect the reflected light energy at 10Mv, has the function of window extraction, and realizes star point extraction greater than 500Hz.

[0052] like Figure 2 As shown, the jitter compensation process is as follows: the collimated image of the graticule is split into two beams by the beam splitter, one is a signal light (test light) and the other is a reference light. The signal light passes through the entire jitter compensation system and enters the sensor. Part of the energy of the on-axis light spot is reflected back to the microscopic imaging system through the reflector at the front end of the sensor to obtain a signal light spot. The other reference light directly enters the behavioral imaging system to obtain another reference light spot. The microscopic imaging system extracts the centroid of the two detected light spots and confirms the offset compared with the case without jitter compensation. If there is an offset, the pitch and yaw axes of the jitter compensation mirror are driven to compensate, and the offset between the signal light spot and the reference light spot is re-determined. The above process is repeated until there is no offset between the signal light spot and the reference light spot. After the jitter compensation is completed, monitoring is performed at the next moment. Since the response frequency of the jitter compensation system and the detection imaging frequency are both not less than 500 Hz, the above jitter compensation process is completed in milliseconds.

[0053] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A jitter compensation device for a high-precision pointing system, characterized in that include: An adjustable color temperature light source (1), a graticule (2), an adjustable aperture (3), a light source collimation system (4), a beam splitting system (5), a neutral attenuation plate (6), a reflector (7), a jitter compensation system (11), a signal light beam expansion system (12), a reference light beam expansion system (8), a microscopic imaging system (9), a detector (10), a sensor (13) and a mounting bracket (14) thereof; The adjustable color temperature light source (1) emits quasi-monochromatic light and composite light of different color temperatures to illuminate the reticle (2), which is collimated into quasi-parallel light by a light source collimation system (4), and then split into a reference beam and a test beam by a beam splitting system (5), wherein the reference beam propagates toward a neutral attenuation plate (6), and the test beam propagates toward a jitter compensation system (11). An adjustable aperture (3) is provided between the reticle (2) and the light source collimation system (4) to control the amount of light transmitted and suppress stray light. The reference beam first passes through a neutral attenuation plate (6) for a first energy attenuation, then passes through a reflector (7) and then passes through the neutral attenuation plate (6) for a second energy attenuation. The beam after the second energy attenuation is split by a beam splitting system (5) to form a second reference beam and a third reference beam. The second reference beam propagates toward a reference light beam expansion system (8), and the third reference beam propagates toward a light source collimation system (4). The third reference beam is a non-working beam and is absorbed by the structure. After the second reference beam is expanded, it is directly imaged by a microscopic imaging system (9) and received by a detector (10). The test beam passes through the jitter compensation system (11) and the signal light beam expansion system (12) and finally reaches the focal plane of the sensor (13). A reflector is arranged at the entrance of the secondary mirror of the sensor. A part of the test beam is reflected by the reflector back to the signal light beam expansion system (12) and then propagates to the beam splitting system (5) through the jitter compensation system (11) to form a second test beam and a third test beam. The third test beam propagates toward the light source collimation system (4). The third test beam is a non-working beam and is absorbed by the structure. The second test beam propagates toward the reference light beam expansion system (8), is expanded by the beam expansion system and amplified by the microscope system, and is also received by the detector (10). The adjustable color temperature light source (1) uses LED as a light source, and emits quasi-monochromatic light and composite light of different color temperatures. The energy of the emitted light meets the sensitivity requirement of the pointing measurement sensor (13) for stars, which is 0Mv to 10Mv. The spectral range of the adjustable color temperature light source (1) is the full spectrum of 400nm to 900nm. The neutral attenuation plate (6) attenuates the energy of the reference beam to ensure that the energy difference between the light spot of the second test beam and the light spot of the second reference beam is within 10%. The neutral attenuation plate (6) also limits the aperture of the reference beam. The angle between the reflector (7) and the optical axis is 90.2°, so that the pixel spacing between the return light spot of the second reference beam and the return light spot of the second test beam is greater than 50 pixels; The jitter compensation reflector (11) can rotate around two axes to adjust the direction of the emitted light. The jitter frequency of the jitter compensation reflector (11) is greater than 500 Hz. The PID is used to control the swing of the jitter compensation reflector, thereby achieving compensation for environmental jitter not greater than 100 Hz. The two axes are respectively a pitch axis and a yaw axis. The signal light beam expansion system (12) is a telescopic system that expands a 30 mm light beam to 200 mm. The signal light beam expansion system (12) adopts a two-reflection design, the primary mirror is a positive axis parabola, and the secondary mirror adopts a positive axis hyperboloid; The sensor (13) is a star sensor to be measured, and the mounting bracket (14) is used for mounting the sensor (13); The reference light beam expansion system (8) includes two-stage beam expansion. The beam expansion process is to first expand the 3.2 mm beam into 40 mm, and then expand the 40 mm beam to 400 mm. The first-stage beam expansion adopts the structure of a transmission telescope system, and the second-stage beam expansion system adopts a two-reflection design with a beam expansion ratio of 12.5 times. The primary and secondary mirrors are designed as positive axis parabolic mirrors, and both the primary and secondary mirrors are made of microcrystalline glass. The microscopic imaging system (9) amplifies the reference light and the signal light for imaging. The microscopic imaging system (9) adopts a two-reflector design to converge the obtained 400 mm light beam, with a focal length of 5000 mm. The primary mirror is a positive axis parabola, and the secondary mirror is a positive axis hyperboloid. The detection imaging system (10) is capable of detecting light energy reflected back at 10 Mv and achieving star point extraction greater than 500 Hz.

2. The jitter compensation device for a high-precision pointing system according to claim 1, characterized in that: The graticule (2) is processed by mask etching. The types of star points distributed on the graticule include stars in a specific sky area and array star points. The distributed star points have different calibers. In order to ensure the intensity of the signal light return energy, the diameter of the central star point is designed to be 400 microns. The peripheral star points are etched by equating the star point diameter with the relationship between the magnitudes of different star points.

3. The jitter compensation device for a high-precision pointing system according to claim 2, characterized in that: The light source collimation system (4) performs aberration elimination processing on the entire spectrum to ensure that the size of the diffuse spot is smaller than the minimum star point diameter of the graticule.

4. The jitter compensation device for a high-precision pointing system according to claim 1, characterized in that: The beam splitting system (5) controls the splitting ratio to be 50%:50% to split the collimated light beam.

5. A jitter compensation method implemented by the jitter compensation device for a high-precision pointing system according to any one of claims 1 to 4, characterized in that Here are the steps: Step 1: The microscopic imaging system extracts the centroid of the two detected light spots; Step 2: The center of mass obtained by the second test beam is returned and compared with the case without jitter compensation to confirm the offset. If there is an offset, the pitch and yaw axes of the jitter compensation mirror are driven to compensate; Step three: re-determine the offset of the light spot formed by the second test beam and the second reference beam through the microscopic imaging system, and repeat steps two and three until there is no offset of the light spot formed by the second test beam and the second reference beam. After the jitter compensation is completed, monitor the next moment.

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