A self-collimation method with a front-mounted far-infrared focusing system

Abstract

This invention discloses a self-collimation method for an infrared converging system with a front-mounted telescope, belonging to the field of precision optomechanical assembly and adjustment technology for airborne optoelectronic aiming systems. First, a laser interferometer is used to adjust the front-mounted telescope component to the central field of view. Then, an adjustable divergence plate with a scale is adjusted at the exit optical path of the eyepiece assembly. The tilt angle of the self-collimated image is monitored and adjusted using a theodolite, and the diverged image is shifted and centered by adjusting the position of the divergence plate using the emitted light beam. Finally, a visible light parallel plate is replaced to achieve through-axis alignment between the front-mounted telescope system and the rear-mounted focusing and converging system. This method achieves self-collimation of the telescope optical path and the converging system, eliminates beam obstruction problems, provides objective quantification and high precision, and is applicable to self-collimation of similar infrared systems, demonstrating strong versatility.

Description

Technical Field

[0001] This invention belongs to the field of precision optomechanical assembly and adjustment technology of airborne optoelectronic aiming systems, specifically relating to a self-collimation method including a front-mounted far-infrared converging system. Background Technology

[0002] An airborne electro-optical targeting system is an integrated optoelectronic device that combines aiming, tracking, measurement, and imaging. This system can simultaneously carry different types of optical sensors to sense and identify the geometric and physical characteristics of target objects, thereby achieving aiming and tracking. To adapt to all-weather observation, typical electro-optical targeting systems often carry different types of optical payloads such as infrared thermal imagers, television viewing devices, and laser rangefinders, forming a multi-sensor, multi-spectral, and multi-optical-path fusion optoelectronic device system. With the development of aviation, the resolution requirements for airborne electro-optical targeting systems are increasing, prompting the development of airborne electro-optical systems towards larger apertures, longer focal lengths, and wider wavelengths. This system achieves a high degree of integration of visible and infrared optical paths through a front-mounted common-aperture reflective telescope system, possessing numerous advantages such as long focal length, multi-band, high resolution, and compact structure.

[0003] The common aperture airborne electro-optical aiming system mainly consists of a front-mounted telescope 1, a precision stabilizer 2, a beam splitter 3, an infrared focusing and converging component 4, a television viewing sight 5, and an infrared thermal imager 6. These components are assembled on the platform frame 7. See the attached diagram for a detailed optical path schematic. Figure 1 As shown, the system comprises a front-mounted infrared converging system consisting of components 1, 2, 3, and 4. Because the beam splitter (component 3) deflects the original incident beam, light blocking occurs when the telescope's outgoing light reaches the converging system. Generally, optical systems employ through-axis collimation techniques, adjusting the autocollimation and divergence images of the two diverging plates to achieve collimation. However, traditional through-axis techniques have two limitations for this optical system. First, the beam splitter is a semi-reflective mirror, reflecting visible light and transmitting infrared beams, making it impossible to observe the diverging plates of the converging system from in front of the system. Second, the outgoing light from the front-mounted telescope is parallel, making it impossible to accurately determine the beam center position. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To avoid the shortcomings of existing technologies, this invention provides a self-collimation method with a front-mounted infrared converging system. By using a design that aligns the diverging plate and visible light parallel to assist the axis-crossing device, and with the aid of equipment such as a laser interferometer, plane mirror, theodolite, and internal focusing tube, it achieves precise axis-crossing between the front-mounted unfocused telescope system and the rear-mounted focusing converging system, as well as axis-crossing of the infrared system in the visible light band.

[0006] The technical solution of this invention is: a self-collimation method with a front-mounted far-infrared focusing system, the specific steps of which are as follows:

[0007] Step 1: Locate the center field of view of the telescope component;

[0008] a) Adjust the laser interferometer and the standard plane mirror to be collimated to minimize interference fringes;

[0009] b) Assemble the telescope components onto the platform frame, and place the platform frame on the three-dimensional adjustment stage;

[0010] c) Place the three-dimensional adjustment stage between the laser interferometer and the standard plane mirror, so that the entire telescope component on it is moved into the incident envelope of the parallel light of the laser interferometer.

[0011] d) Locate the center field of view of the telescope component by adjusting the azimuth and pitch angles of the three-dimensional adjustment platform;

[0012] Step 2: Establish the through-axis reference for the telescope's optical path;

[0013] a) Install a multidimensional adjustable beam splitter behind the beam emitted from the eyepiece group of the telescope component. The beam emitted by the laser interferometer is then projected onto the multidimensional adjustable beam splitter after being compressed by the telescope component.

[0014] b) Set up a theodolite between the multidimensional adjustable dividing plate and the standard plane mirror;

[0015] c) Adjust the position and angle of the theodolite to complete the adjustment of the adjustable autocollimation image and establish the reference.

[0016] Step 3: Calibrate the center and angular deviation of the beam emitted from the telescope components;

[0017] a) Adjust the multidimensional adjustable beam splitter to align with the theodolite so that the laser interferometer's output beam is located at the center of the multidimensional adjustable beam splitter;

[0018] b) Position the telescope components onto the platform frame using pins;

[0019] Step 4: Autocollimation of the internal focusing tube and the multidimensional adjustable focusing plate;

[0020] a) Remove the telescope components;

[0021] b) Install an internal focusing light tube in front of the multidimensional adjustable focusing plate;

[0022] c) By adjusting the position and angle of the internal focusing tube, the internal focusing tube and the multidimensional adjustable dividing plate are auto-aligned, and the internal focusing tube is locked.

[0023] Step 5: Visible light path through the axis;

[0024] a) Remove the multidimensional adjustable beam splitter and install a fine stabilizer, a visible light parallel plate, and a focusing system tube along the optical path, wherein the visible light parallel plate replaces the original beam splitter in the optical path;

[0025] b) Install the centering car deflector plate inside the telescope tube of the converging system;

[0026] c) Adjust the centering car's self-alignment plate to complete the visible light path through the axle;

[0027] Step 6: Through-axis collimation including the front-mounted far-infrared converging system;

[0028] a) Remove the visible light parallel plate and replace it with a beam splitter;

[0029] b) Assemble the front telescope component according to the pin positions in step 3;

[0030] c) Remove the centering plate and install the converging lens assembly inside the converging system's lens barrel to complete the through-axis collimation of the infrared converging system.

[0031] A further technical solution of the present invention is: in step 1, the azimuth and pitch angle of the three-dimensional adjustment stage is adjusted to minimize the wavefront RMS value of the telescope component, and the Zernike coefficient astigmatism and coma terms tend to return to zero. At this time, the center field of view position of the telescope component is obtained.

[0032] A further technical solution of the present invention is as follows: In step 2, the theodolite adjustment method is as follows: First, adjust the left and right and altitude positions of the theodolite to be roughly the same as the multidimensional adjustable dividing plate; then adjust the theodolite to be aligned with the standard plane mirror, record the pitch angle θ1 displayed by the theodolite at this time, and zero the azimuth angle; then rotate the theodolite around the vertical geodetic reference axis while observing the multidimensional adjustable dividing plate, rotate the azimuth by 180°, and rotate the pitch to θ2, where θ1+θ2=180°; finally, lock the theodolite.

[0033] A further technical solution of the present invention is as follows: In step 3, the azimuth and pitch angle of the multidimensional adjustable dividing plate is adjusted to make it collimated with the theodolite; then, the translation of the multidimensional adjustable dividing plate is adjusted so that the laser interferometer's output beam is exactly located at the center of the scale dividing plate, that is, the beam is symmetrical left and right and up and down.

[0034] A further technical solution of the present invention is: in step 4, the translation position and angle of the internal focusing tube are adjusted, and the autocollimation deviation of the multidimensional adjustable differentiation plate is adjusted to within 10″, and the differentiation deviation is adjusted to within 0.01mm.

[0035] A further technical solution of the present invention is as follows: In step 5, the autocollimation image and the diverging image of the converging system are observed by the internal focusing light tube. By adjusting the translation and angle of the stabilizing lens and the converging system, the deviation of the autocollimation image of the centering car diverging plate is adjusted to within 10″ and the deviation of the diverging image is adjusted to within 0.01mm.

[0036] A further technical solution of the present invention is: the multidimensional adjustable beam splitter includes a beam splitter and a beam splitter base. The beam splitter is a transmission type beam splitter with standard graduations on the crosshairs, which can accurately determine the degree of eccentricity of the incident beam. The beam splitter base is used to transfer the beam splitter to the platform frame behind the telescope component. It is designed with a set screw hole, and the tilting and translation adjustment of the beam splitter is realized by the set screw.

[0037] A further technical solution of the present invention is: the material of the beam splitter is zone-melted single-crystal silicon, the A side is coated with a beam splitting film, the B side is coated with an anti-reflection film, and the average transmittance is ≥97% near the wavelength of 3.7μm.

[0038] A further technical solution of the present invention is that the working wavelength of the internal focusing optical tube is 550nm.

[0039] A further technical solution of the present invention is that the visible light parallel plate is made of HK9L optical glass with a thickness of 6.68mm.

[0040] Beneficial effects

[0041] The beneficial effects of this invention are as follows: This invention designs a multidimensional adjustable scale-mounted beam splitter, which can realize the center and angular deviation calibration of the emitted beam in the central field of view of the afocal telescope system, and use it as the cross-axis reference for the infrared converging system. At the same time, it proposes a parallel flat plate visible light design method, which can replace the original optical path infrared beam splitter to realize the cross-axis optical system in the visible light band.

[0042] The method of this invention first uses a laser interferometer to adjust the front telescope component to the central field of view. Then, an adjustable divergence plate with a scale is adjusted at the exit optical path of the eyepiece group. The tilt angle of the autocollimation image is monitored and adjusted using a theodolite. Finally, the diverged image is shifted and centered by adjusting the position of the divergence plate using the emitted light beam. The visible light parallel plate is replaced to achieve through-axis alignment between the front telescope system and the rear focusing and converging system. This method achieves self-collimation of the telescope optical path and the converging system, eliminates beam obstruction problems, provides objective quantification and high precision, and is applicable to the self-collimation of similar infrared systems, demonstrating strong versatility. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the optical path of a common aperture airborne electro-optical aiming system.

[0044] Figure 2 This is a structural diagram of a multidimensional adjustable graduated differentiation plate.

[0045] Figure 3 This is an optical design diagram of the beam splitter for an infrared converging system.

[0046] Figure 4 This is an optical design diagram for a visible light transaxial parallel plate.

[0047] Figure 5 This is a flowchart of a cross-axis system including a front-mounted far-infrared converging system.

[0048] Figure 6 Find the schematic diagram for the center field of view of the front telescope component.

[0049] Figure 7 Establish a schematic diagram for the through-axis reference of the front telescope optical path.

[0050] Figure 8 This is a schematic diagram of the through-axis collimation principle of a far-infrared converging system with a front-mounted telescope.

[0051] Explanation of reference numerals in the attached drawings: 1—Telescope component, 2—Precision stabilizer, 3—Beam splitter, 4—Infrared focusing and converging component, 5—Television viewing sight, 6—Infrared thermal imager, 7—Platform frame, 8—Diverging plate, 9—Diverging plate base, 10—Laser interferometer, 11—Standard plane mirror, 12—Three-dimensional adjustment stage, 13—Multi-dimensional adjustable diverging plate, 14—Theodolite, 15—Internal focusing light tube, 16—Visible light parallel plate, 17—Converging system diverging plate, 18—Converging system lens tube. Detailed Implementation

[0052] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0053] The multidimensional adjustable differentiation plate 13 designed in this invention is shown in the appendix. Figure 2 As shown, it mainly consists of a beam splitter plate 8 and a beam splitter plate holder 9. The beam splitter plate 8 is a transmission type beam splitter plate with standard graduations on the crosshairs, which can accurately determine the degree of eccentricity of the incident beam. The beam splitter plate holder 9 can be transferred and installed on the rear platform frame of the telescope system. It is designed with set screw holes, through which the tilt and translation adjustment of the beam splitter plate can be realized.

[0054] The beam splitter design of the infrared converging system is shown in the attached figure. Figure 3 As shown, the material is zone-melted single-crystal silicon, with a beam-splitting film coated on side A and an anti-reflection film coated on side B. The average transmittance is ≥97% near a wavelength of 3.7μm. To ensure that the beam in the instrument's working wavelength band can pass through the beam splitter with the same translation amount as the infrared working wavelength band, this invention designs a replacement for the parallel plate. It is known that the focusing tube inside the through-axis instrument operates at 550nm, using HK9L optical glass. The parallel plate thickness is designed to be 6.68mm. This design can replace the original infrared beam splitter to achieve through-axis optical systems in the visible light band. The design diagram is attached. Figure 4.

[0055] Using the two auxiliary through-axis devices designed above, and with the aid of equipment such as a laser interferometer, plane mirror, theodolite, and internal focusing tube, autocollimation through-axis alignment with a front-mounted far-infrared converging system can be achieved. A flowchart of this method is attached. Figure 5 The specific steps are as follows:

[0056] Step 1: Refer to the appendix Figure 6 As shown, the laser interferometer 10 is collimated with the standard plane mirror 11 to minimize interference fringes. The telescope component 1 is assembled onto the platform frame 7, and then the assembly is placed on the three-dimensional adjustment stage 12, which is positioned between the laser interferometer 10 and the standard plane mirror 11. The entire telescope component 1 is moved into the incident envelope of the parallel light from the laser interferometer 10. The azimuth and pitch angles of the three-dimensional adjustment stage 12 are adjusted to minimize the wavefront RMS value of the telescope component 1, and to bring the Zernike coefficient astigmatism and coma terms to near zero. This position represents the center field of view of the telescope component.

[0057] Step 2: Refer to the appendix Figure 7 As shown, a multidimensional adjustable beam refraction plate 13 is mounted on the platform frame 7 at the corresponding position behind the beam emitted from the eyepiece group of the telescope component 1. The beam emitted by the laser interferometer 10 is then projected onto the multidimensional adjustable beam refraction plate 13 after being compressed by the telescope component 1. A theodolite 14 is set up between the platform frame 7 and the standard plane mirror 11. The left-right and height orientation of the theodolite 14 is adjusted to be roughly the same as that of the multidimensional adjustable beam refraction plate 13. The theodolite 14 is then adjusted so that its crosshairs are aligned with the standard plane mirror 11. The elevation angle θ1 displayed on the theodolite 14 is recorded, and the azimuth angle is zeroed. The theodolite 14 is rotated around the vertical geodetic reference axis to observe the multidimensional adjustable beam refraction plate 13, with the azimuth rotating 180° and the elevation rotating to θ2, where θ1 + θ2 = 180°. The theodolite 14 is locked, completing the establishment of the autocollimation adjustment reference for the multidimensional adjustable beam refraction plate 13.

[0058] Step 3: Adjust the azimuth and elevation angles of the multi-dimensional adjustable dividing plate 13 to align the dividing plate 8 with the electric crosshairs of the theodolite 14. Adjust the translation of the multi-dimensional adjustable dividing plate 13 (translation within a plane perpendicular to the optical axis) so that the beam emitted from the laser interferometer 10 is precisely at the center of the scale dividing plate 8, i.e., the beam is symmetrical left, right, up, and down. Position and angle adjustments can be performed simultaneously. After adjustment, use pins to position the telescope component 1.

[0059] Step 4: Refer to the appendix Figure 8The infrared converging system shown is optically cross-axis mounted. This system mainly consists of an internal focusing light tube 15, a multi-dimensional adjustable refraction plate 13, a fine-stabilizing lens 2, a visible light parallel plate 16, a converging system refraction plate 17, a converging system lens barrel 18, and a platform frame 7. After step 3, the multi-dimensional adjustable refraction plate 13 has been adjusted and assembled onto the platform frame 7. The telescope component 1 is removed, and the internal focusing light tube 15 is installed in front of the multi-dimensional adjustable refraction plate 13. The translation and angle of the internal focusing light tube 15 are adjusted so that the autocollimation deviation of the multi-dimensional adjustable refraction plate 13 is adjusted to within 10″, and the refraction deviation is adjusted to within 0.01mm. The internal focusing light tube 15 is then locked.

[0060] Step 5: Remove the multidimensional adjustable splitter plate 13, replace the original optical path beam splitter 3 with the visible light parallel plate 16 designed in this invention, assemble the centering splitter plate in the converging system tube 18, observe the autocollimation image and split image of the converging system splitter plate 17 through the internal focusing light tube 15, and adjust the autocollimation image deviation of the converging system splitter plate 17 to within 10″ and the split image deviation to within 0.01mm by adjusting the translation and angle of the stabilizing lens 2 and the converging system tube 18.

[0061] Step 6: Remove the visible light parallel plate 16 and replace it with the formal beam splitter 3. Assemble the front telescope component 1 according to the pin position. Remove the converging system splitter plate 17 and replace it with the converging lens group to complete the collimation through-axis of the infrared converging system.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A self-collimation method including a front-mounted far-infrared converging system, characterized in that... The specific steps are as follows: Step 1: Locate the center field of view of the telescope component; a) Adjust the laser interferometer and the standard plane mirror to be collimated to minimize interference fringes; b) Assemble the telescope components onto the platform frame, and place the platform frame on the three-dimensional adjustment stage; c) Place the three-dimensional adjustment stage between the laser interferometer and the standard plane mirror, so that the entire telescope component on it is moved into the incident envelope of the parallel light of the laser interferometer. d) Locate the center field of view of the telescope component by adjusting the azimuth and pitch angles of the three-dimensional adjustment platform; Step 2: Establish the through-axis reference for the telescope's optical path; a) A multidimensional adjustable beam splitter is installed behind the beam emitted from the eyepiece assembly of the telescope component. The beam emitted by the laser interferometer is projected onto the multidimensional adjustable beam splitter after passing through the telescope component. The multidimensional adjustable beam splitter includes a beam splitter and a beam splitter holder. The beam splitter is a transmission type beam splitter with standard graduations on the crosshairs, which can accurately determine the degree of eccentricity of the incident beam. The beam splitter holder is used to transfer the beam splitter to the platform frame behind the telescope component. It is designed with set screw holes, and the tilt and translation adjustment of the beam splitter is realized through the set screws. b) Set up a theodolite between the multidimensional adjustable dividing plate and the standard plane mirror; c) Adjust the position and angle of the theodolite to complete the adjustment of the adjustable autocollimation image and establish the reference. Step 3: Calibrate the center and angular deviation of the beam emitted from the telescope components; a) Adjust the multidimensional adjustable beam splitter to align with the theodolite so that the laser interferometer's output beam is located at the center of the multidimensional adjustable beam splitter; b) Position the telescope components onto the platform frame using pins; Step 4: Autocollimation of the internal focusing tube and the multidimensional adjustable focusing plate; a) Remove the telescope components; b) Install an internal focusing light tube in front of the multidimensional adjustable focusing plate; c) By adjusting the position and angle of the internal focusing tube, the internal focusing tube and the multidimensional adjustable dividing plate are auto-aligned, and the internal focusing tube is locked. Step 5: Visible light path through the axis; a) Remove the multidimensional adjustable beam splitter and install a fine stabilizer, a visible light parallel plate, and a focusing system tube along the optical path, wherein the visible light parallel plate replaces the original beam splitter in the optical path; b) Install the centering car deflector plate inside the telescope tube of the converging system; c) Adjust the centering car's self-alignment plate to complete the visible light path through the axle; Step 6: Through-axis collimation including the front-mounted far-infrared converging system; a) Remove the visible light parallel plate and replace it with a beam splitter; b) Assemble the front telescope component according to the pin positions in step 3; c) Remove the centering plate and install the converging lens assembly inside the converging system's lens barrel to complete the through-axis collimation of the infrared converging system.

2. The self-collimation method of a far-infrared converging system with a front-mounted telescope according to claim 1, characterized in that: In step 1, the azimuth and pitch angles of the three-dimensional adjustment stage are adjusted to minimize the wavefront RMS value of the telescope component, and the Zernike coefficient astigmatism and coma terms tend to return to zero. At this point, the center field of view of the telescope component is located.

3. The self-collimation method of a far-infrared converging system with a front-mounted telescope according to claim 1, characterized in that: In step 2, the theodolite is adjusted as follows: First, adjust the left-right and height orientation of the theodolite to be roughly the same as the multidimensional adjustable dividing plate; then adjust the theodolite to be aligned with the standard plane mirror, record the pitch angle θ1 displayed by the theodolite at this time, and zero the azimuth angle; then rotate the theodolite around the vertical geodetic reference axis while observing the multidimensional adjustable dividing plate, rotate the azimuth by 180°, and rotate the pitch to θ2, where θ1+θ2=180°; finally, lock the theodolite.

4. The self-collimation method of a far-infrared converging system with a front-mounted telescope according to claim 1, characterized in that: In step 3, the azimuth and pitch angle of the multidimensional adjustable dividing plate is adjusted to make it aligned with the theodolite; then, the translation of the multidimensional adjustable dividing plate is adjusted so that the laser interferometer's output beam is exactly at the center of the scale dividing plate, that is, the beam is symmetrical left and right and up and down.

5. The self-collimation method of a far-infrared converging system with a front-mounted telescope according to claim 1, characterized in that: In step 4, the translation position and angle of the internal focusing tube are adjusted to adjust the autocollimation deviation of the multidimensional adjustable differentiation plate to within 10″ and the differentiation deviation to within 0.01mm.

6. The self-collimation method of a far-infrared converging system with a front-mounted telescope according to claim 1, characterized in that: In step 5, the autocollimation image and the diverging image of the converging system are observed by the internal focusing light tube. By adjusting the translation and angle of the stabilizing lens and the converging system, the deviation of the autocollimation image of the centering car diverging plate is adjusted to within 10″ and the deviation of the diverging image is adjusted to within 0.01mm.

7. A self-collimation method for a far-infrared converging system with a front-mounted telescope according to any one of claims 1-6, characterized in that: The beam splitter is made of zone-melted single-crystal silicon, with a beam splitting film on surface A and an anti-reflection film on surface B, achieving an average transmittance of ≥97% near a wavelength of 3.7μm.

8. A self-collimation method for a far-infrared converging system with a front-mounted telescope according to any one of claims 1-6, characterized in that: The internal focusing optical tube operates at a wavelength of 550nm.

9. A self-collimation method for a far-infrared converging system with a front-mounted telescope according to any one of claims 1-6, characterized in that: The visible light parallel plate is made of HK9L optical glass with a thickness of 6.68mm.

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