Optical axis registration system and method for assembling large optical systems with limited space

Abstract

The application discloses a system and method for aligning optical axes of large optical systems with limited installation space. The system comprises a front optical system with parallel outgoing light and a rear optical system with parallel incoming light. The front optical system comprises a front optical system optical axis mark mirror, and the rear optical system comprises an electrically-controlled folding mirror and a rear optical system optical axis mark mirror. An auxiliary light calibration component is arranged in the interfacing light path of the front optical system and the rear optical system. A self-collimator is arranged to emit a test light beam with an optical axis perpendicular to the interfacing light path of the front optical system and the rear optical system. The auxiliary light calibration component comprises a first parallel flat plate, a first 45-degree mirror, a second 45-degree mirror and a second parallel flat plate. The first 45-degree mirror and the second 45-degree mirror are arranged between the first parallel flat plate and the second parallel flat plate to form an included angle of 90 degrees. The application can realize high-precision alignment of optical axes of two large optical systems with large volume and mass under the condition of limited installation space.

Description

Technical Field

[0001] This invention belongs to the field of precise optical axis registration technology for large optical systems with limited assembly and adjustment space, and specifically relates to an optical axis registration system and method for large optical systems with limited assembly and adjustment space. Specifically, it refers to a large optical interference payload system where the front-end optical-mechanical system is a large-aperture beam expander and the rear-end optical-mechanical system is an infrared receiver. It is also applicable to optical axis registration of front-end and rear-end optical-mechanical systems in the field of space laser communication. Technical Background

[0002] The optical-mechanical payload system of the space vertical detection interferometer consists of a front-mounted large-aperture beam expander optical-mechanical system and a rear-mounted infrared detection optical-mechanical system. With increasingly higher requirements for spatial and spectral resolution, the aperture of the optical-mechanical system is increasing, leading to a larger and heavier payload optical system. The limited pupil matching distance between the front and rear optical systems restricts the assembly and adjustment space for optical axis registration. Traditional registration methods involve first aligning the theodolite with the marker mirror of the front optical-mechanical system, then rotating it 180° to view the returned image from the marker mirror of the rear optical-mechanical system. By adjusting the rear optical-mechanical system to align its marker mirror with the theodolite, optical axis registration is achieved. This process requires space for the theodolite's placement and rotation, as well as observation space for the test personnel, making it difficult to meet the practical requirement of limited space for payload assembly and adjustment. Furthermore, due to the large size and weight of the rear optical-mechanical system, precise optical axis registration can no longer be achieved by adjusting it. Summary of the Invention

[0003] The purpose of this invention is to provide an optical axis registration system and method for large optical systems with limited assembly and adjustment space. It solves the technical problem that the optical axis registration test space between the front and rear optical engine systems is limited, and that the front and rear optical engine systems are large and heavy, making it impossible to perform high-precision optical axis registration by moving either the front or rear optical engine system. This invention can achieve high-precision registration of the optical axes of two large, heavy optical systems under limited assembly and adjustment space.

[0004] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows: A registration system for optical axes in large optical systems with limited assembly space is characterized in that: it includes a pre-optical engine system with parallel outgoing light and a post-optical engine system with parallel incident light; the pre-optical engine system includes a pre-optical engine system optical axis marker mirror, and the post-optical engine system includes an electrically controlled folding mirror and a post-optical engine system optical axis marker mirror; An auxiliary optical calibration component is placed in the docking optical path between the front-end optical engine system and the rear-end optical engine system. An autocollimator is also provided in which the optical axis of the emitted test beam is perpendicular to the docking optical path between the front-end and rear-end optical engine systems. The auxiliary optical correction component includes a first parallel plate, a first 45° reflector, a second 45° reflector, and a second parallel plate; the first 45° reflector and the second 45° reflector are arranged at an angle of 90° between the first parallel plate and the second parallel plate, which are arranged parallel to each other.

[0005] The optical axis registration system for large optical systems with limited assembly and adjustment space is characterized in that: a primary mirror, a secondary mirror, a third mirror, and an optical axis marker mirror of the pre-optical-mechanical system are arranged sequentially on the optical path of the pre-optical-mechanical system; and an electrically controlled folding mirror, an optical axis marker mirror of the pre-optical-mechanical system, a converging mirror, and a detector are arranged sequentially on the optical path of the post-optical-mechanical system.

[0006] A method for optical axis registration using the above-described system is applicable to situations where the optical axis registration test space between the pre-optical and post-optical systems is limited, and the pre-optical and post-optical systems are large and heavy, making it impossible to perform high-precision optical axis registration by moving either the pre-optical or post-optical system; characterized in that: A. An autocollimator is used as the optical axis angle deviation testing device. The test light emitted by the autocollimator is split into two beams of test light after passing through the first 45° reflector and the second 45° reflector. B. The first test light passes through the first parallel plate and reaches the optical axis marker mirror of the front optical-mechanical system. The auxiliary optical calibration component and the autocollimator are adjusted so that the test light reflected back from the front surface of the first parallel plate coincides with the test light returned by the optical axis marker mirror of the front optical-mechanical system, thus completing the optical axis registration between the auxiliary optical calibration component and the front optical-mechanical system. C. The second test light passes through the second 45° reflector, the second parallel plate, and the electrically controlled folding mirror, and is incident on the optical axis marker mirror of the rear optical-mechanical system. After being reflected by the optical axis marker mirror of the rear optical-mechanical system, it passes through the electrically controlled folding mirror, the second parallel plate, and the second 45° reflector back to the autocollimator. The autocollimator displays the angle difference between the signals returned by the optical axis marker mirrors of the front and rear optical-mechanical systems, which is the optical axis angle deviation between the front and rear optical-mechanical systems. The pitch and azimuth angles of the electrically controlled folding mirror are adjusted so that the test light split by the second 45° reflector passes through the second parallel plate, then through the electrically controlled folding mirror, and the test light returned by the optical axis marker mirror of the rear optical-mechanical system coincides with the test light returned by the optical axis marker mirror of the front optical-mechanical system, thus completing the registration of the optical axes of the front and rear optical-mechanical systems.

[0007] The method is characterized in that: the electrically controlled folding mirror is a motor-controlled reflector that rotates in two dimensions, namely pitch and azimuth, with a controlled angular rotation accuracy of 1 second. The control motor of the electrically controlled folding mirror is given control commands through two test signals returned by the autocollimator, so that it drives the electrically controlled folding mirror to precisely adjust the pitch and azimuth angles until the test light signal returned by the optical axis marker mirror of the pre-optical-mechanical system and the test light signal returned by the optical axis marker mirror of the post-optical-mechanical system are completely superimposed, that is, the optical axis directions marked by the two marker mirrors are consistent.

[0008] The method is characterized in that: the diameter of the first parallel plate and the second parallel plate is 20 mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the surface of the plate near the first 45° reflector and the second 45° reflector is coated with a 532 nm transmittance of 70% ± 5%, and the other side is coated with a 532 nm transmittance of better than 98%; the transmission wavefront is better than 1 / 50 of the wavelength, with a wavelength of 532 nm.

[0009] The method is characterized in that: the first 45° reflector and the second 45° reflector have an aperture of 30mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the included angle between them is 90°, and the assembly and adjustment ensure that the included angle is 90°±0.5 seconds; the front and rear surfaces are coated with aluminum reflective film, the film is applied close to the first and second parallel plates, and the reflectivity of 532nm is better than 97% when measured at 45°, and the film is applied on the other side, and the reflectivity of 633nm is better than 97% when measured at 45°; its reflected wavefront is better than 1 / 50 wavelength when measured at 45°, and the wavelength is 532nm.

[0010] The method is characterized in that: Before step A, there is also an inspection step for the auxiliary optical calibration components, specifically: The test light emitted by the autocollimator is split into two beams after passing through the first 45° reflector and the second 45° reflector. One beam reaches the front surface of the first parallel plate, and approximately 30% of the beam is reflected back to the autocollimator. The other beam reaches the front surface of the second parallel plate, and approximately 30% of the beam is reflected back to the autocollimator. The two beams overlap. The two beam paths are blocked respectively, and the angle between the two returning beams is measured. If the angle difference is less than 1 second, the auxiliary optical calibration component is considered to meet the test requirements.

[0011] The method is characterized in that: Before step A, there is also a process of optical axis registration and calibration between the pre- and post-optical-mechanical systems. Specifically, the auxiliary optical calibration component is placed in the docking optical path between the pre- and post-optical-mechanical systems, and the autocollimator is placed outside the pre- and post-optical-mechanical systems with the optical axis of the test beam emitted by the autocollimator perpendicular to the docking optical path between the pre- and post-optical-mechanical systems. The beneficial effects of this invention are as follows: This invention utilizes a parallel plate and a 45° reflector to construct a small-volume auxiliary optical calibration component. The testing space is significantly smaller than that of traditional theodolite testing schemes. Since the beams in the auxiliary optical calibration path of the component are all parallel, the auxiliary optical calibration path can be proportionally reduced to accommodate the limitations of the testing space. Applying the auxiliary optical calibration path allows the angle testing instrument to be moved outside the optomechanical system, solving the problem that the optical axis angle testing of the front and rear optomechanical systems under compact spatial load structures cannot be performed using traditional methods. Unlike the traditional method of placing the optical axis marker mirror outside the system, this invention places the optical axis marker mirror of the rear optomechanical system within the optical path of the rear optomechanical system, and sets an electrically controlled folding mirror in front of the marker mirror. Based on the optical axis angle deviation of the front and rear optomechanical systems measured by the autocollimator, commands are sent to the motor controlling the electrically controlled folding mirror. The folding mirror angle is precisely adjusted electronically to achieve the goal of accurate alignment of the optical axes of the front and rear optomechanical systems. Using only one electrically controlled folding mirror, the problem of precise optical axis registration in large systems with both front and rear optical-mechanical systems being large in volume and mass cannot be solved by adjusting the angle of the entire system. Moreover, the registration accuracy is high, reaching better than 2 seconds.

[0012] This invention breaks down the traditional inefficient sequential process of assembling and adjusting the pre-optical-mechanical system, aligning it with the post-optical-mechanical system, and then installing the detector into a parallel process where the pre-optical-mechanical system assembly and adjustment, the post-optical-mechanical system detector installation, and finally the optical axis alignment are performed, greatly improving work efficiency. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the system of the present invention.

[0014] Figure 2 A schematic diagram of the dual-plate adjustment process used in the inspection of the auxiliary optical calibration components.

[0015] Figure 3 A schematic diagram illustrating the adjustment of the 90° angle between the two 45° reflectors during the inspection process of the auxiliary optical calibration component. Detailed Implementation

[0016] The implementation of the method of the present invention will be described below with reference to the accompanying drawings: Please see Figure 1 This invention discloses an optical axis registration system for large optical systems with limited assembly space. As shown in the figure, it includes a pre-optical engine system with parallel outgoing light and a post-optical engine system with parallel incident light; the pre-optical engine system includes a pre-optical engine system optical axis marker mirror 4, and the post-optical engine system includes an electrically controlled folding mirror 13 and a post-optical engine system optical axis marker mirror 5.

[0017] An auxiliary optical calibration component is placed in the docking optical path between the front and rear optical systems, and an autocollimator 12 is also provided, wherein the optical axis of the emitted test beam is perpendicular to the docking optical path between the front and rear optical systems.

[0018] The auxiliary optical correction component includes a first parallel plate 8, a first 45° reflector 9, a second 45° reflector 10, and a second parallel plate 11; the first 45° reflector 9 and the second 45° reflector 10 are arranged at an angle of 90° between the first parallel plate 8 and the second parallel plate 11, which are arranged parallel to each other.

[0019] In this invention, the optical path of the pre-optical-mechanical system is sequentially provided with a primary mirror 1, a secondary mirror 2, a third mirror 3, and a pre-optical-mechanical system optical axis marker mirror 4; the optical path of the rear-optical-mechanical system is sequentially provided with an electrically controlled folding mirror 13, a rear-optical-mechanical system optical axis marker mirror 5, a converging mirror 6, and a detector 7.

[0020] This invention also discloses a method for optical axis registration using the system described above. This method is applicable to situations where the optical axis registration test space between the front-end and rear-end optical engine systems is limited, and the front-end and rear-end optical engine systems are large and heavy, making it impossible to perform high-precision optical axis registration by moving either the front-end or rear-end optical engine system. The specific steps are as follows: A. The autocollimator 12 is used as the optical axis angle deviation testing device. The test light emitted by it passes through the first 45° reflector 9 and the second 45° reflector 10 and is split into two test beams.

[0021] B. The first test light passes through the first parallel plate 8 and reaches the optical axis marker mirror 4 of the front optical-mechanical system. The auxiliary optical calibration component and the autocollimator 12 are adjusted so that the test light reflected back from the front surface of the first parallel plate 8 coincides with the test light returned by the optical axis marker mirror 4 of the front optical-mechanical system, thus completing the optical axis registration between the auxiliary optical calibration component and the front optical-mechanical system.

[0022] C. The second test light passes through the second 45° reflector 10, the second parallel plate 11, and the electrically controlled folding mirror 13, and is incident on the optical axis marker mirror 5 of the rear optical-mechanical system. After being reflected by the optical axis marker mirror 5 of the rear optical-mechanical system, it passes through the electrically controlled folding mirror 13, the second parallel plate 11, and the second 45° reflector 10 and returns to the autocollimator 12. The autocollimator 12 displays the angle difference between the signals returned by the optical axis marker mirror 4 of the front optical-mechanical system and the optical axis marker mirror 5 of the rear optical-mechanical system, which is the optical axis angle deviation between the front and rear optical-mechanical systems. The pitch and azimuth angles of the electrically controlled folding mirror 13 are adjusted so that the test light split by the second 45° reflector 10 passes through the second parallel plate 11, then through the electrically controlled folding mirror 13, and the test light returned by the optical axis marker mirror 5 of the rear optical-mechanical system coincides with the test light returned by the optical axis marker mirror 4 of the front optical-mechanical system, thus completing the registration of the optical axes of the front and rear optical-mechanical systems.

[0023] In this method, the electrically controlled folding mirror 13 is a motor-controlled reflector that rotates in two dimensions: pitch and azimuth. The controlled angle rotation accuracy is 1 second. The two test signals returned by the autocollimator 12 send control commands to the control motor of the electrically controlled folding mirror 13, causing it to drive the electrically controlled folding mirror 13 to precisely adjust the pitch and azimuth angles until the test light signal returned by the optical axis marker mirror 4 of the pre-optical-mechanical system and the test light signal returned by the optical axis marker mirror 5 of the post-optical-mechanical system are completely superimposed, that is, the optical axis directions marked by the two marker mirrors are consistent.

[0024] In this method, the first parallel plate 8 and the second parallel plate 11 have an aperture of 20 mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the surface coating near the first 45° reflector 9 and the second 45° reflector 10 has a 532 nm transmittance of 70% ± 5%, and the coating on the other side has a 532 nm transmittance of better than 98%; its transmission wavefront is better than 1 / 50 of the wavelength, with a wavelength of 532 nm.

[0025] In this method, the first 45° reflector 9 and the second 45° reflector 10 have an aperture of 30 mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the included angle between them is 90°, and the assembly and adjustment ensure that the included angle is 90°±0.5 seconds; the front and rear surfaces are coated with aluminum reflective film, the film is applied close to the first parallel plate 8 and the second parallel plate 11, and the reflectivity of 532 nm is better than 97% when measured at 45°, and the film is applied on the other side, and the reflectivity of 633 nm is better than 97% when measured at 45°; its reflected wavefront is better than 1 / 50 wavelength when measured at 45°, and the wavelength is 532 nm.

[0026] Before step A, there is also an inspection step for the auxiliary optical calibration components, specifically: The test light emitted from the collimator 12 passes through the first 45° reflector 9 and the second 45° reflector 10, and is split into two test beams. One test beam reaches the front surface of the first parallel plate 8, and nearly 30% of the beam is reflected back to the collimator 12. The other test beam reaches the front surface of the second parallel plate 11, and nearly 30% of the beam is reflected back to the collimator 12. The two beams overlap. The two beam paths are blocked respectively, and the angle between the two returning beams is measured. If the angle difference is less than 1 second, the auxiliary optical calibration component is considered to meet the test requirements.

[0027] Before step A, there is also a process of optical axis registration and optical calibration of the front and rear optical engine systems. Specifically, the auxiliary optical calibration component is placed in the docking optical path between the front and rear optical engine systems, and the autocollimator 12 is placed outside the front and rear optical engine systems, with the optical axis of the test beam emitted by the autocollimator 12 perpendicular to the docking optical path of the front and rear optical engine systems.

[0028] The method of this invention also includes a specific process for adjusting the auxiliary optical calibration component: First, the second parallel plate 11 is tested using a laser interferometer 14, adjusted to zero fringes and fixed. Then, the first parallel plate 8 is placed between the laser interferometer 14 and the second parallel plate 11, adjusted to zero fringes and fixed. Figure 2 As shown. After rotating 90 degrees, fix the first 45° reflector 9. Adjust the second 45° reflector 10 in front of the laser interferometer 14. Using the angle testing function of the laser interferometer, adjust until the angle between the first 45° reflector 9 and the second 45° reflector 10 is 90° ± 0.5 seconds. Figure 3 As shown, the debugging of the optical calibration auxiliary component has been completed.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. All equivalent changes and modifications made within the scope of the claims of this invention should be considered within the technical scope of this invention.

Claims

1. A method for optical axis registration in large optical systems with limited assembly and adjustment space, characterized in that: This method is applicable to situations where the optical axis registration test space between the front-end optical engine system and the rear-end optical engine system is limited, and the front-end optical engine system and the rear-end optical engine system are large and heavy, making it impossible to perform high-precision optical axis registration by moving the front-end optical engine system or the rear-end optical engine system; The method is based on a large optical system optical axis registration system, which includes the optical axis registration of two large optical systems: a front optical system with parallel outgoing light and a rear optical system with parallel incident light. The front optical system includes an optical axis marker mirror (4), and the rear optical system includes an electrically controlled folding mirror (13) and an optical axis marker mirror (5). An auxiliary optical calibration component is placed in the docking optical path between the front optical engine system and the rear optical engine system, and an autocollimator (12) is also provided in which the optical axis of the emitted test beam is perpendicular to the docking optical path of the front and rear optical engine systems. The auxiliary optical calibration component includes a first parallel plate (8), a first 45° reflector (9), a second 45° reflector (10), and a second parallel plate (11); the first 45° reflector (9) and the second 45° reflector (10) are arranged at an angle of 90° between the first parallel plate (8) and the second parallel plate (11), which are arranged parallel to each other; the first 45° reflector (9) and the second 45° reflector (10) are used to split the test beam perpendicularly incident from the autocollimator (12) into two test beams, one of which is a test beam. The test light is directed through the first parallel plate (8) to the optical axis marker mirror (4) of the front optical-mechanical system, and another test light is directed through the second parallel plate (11) to one side of the rear optical-mechanical system. The first parallel plate (8) is used to transmit the corresponding test light and at the same time, it uses its own surface reflection to provide reference return light for completing the optical axis registration of the auxiliary optical calibration component and the front optical-mechanical system. The second parallel plate (11) is used to transmit the corresponding test light so that the test light can reach the optical axis marker mirror (5) of the rear optical-mechanical system and receive the reflected beam. The method includes the following steps: A. The self-collimator (12) is used as the optical axis angle deviation test device. The test light emitted by it passes through the first 45° reflector (9) and the second 45° reflector (10) and is split into two test beams. B. The first test light passes through the first parallel plate (8) and reaches the optical axis marker mirror (4) of the front optical-mechanical system. The auxiliary optical calibration component and the autocollimator (12) are adjusted so that the test light reflected back from the front surface of the first parallel plate (8) coincides with the test light returned by the optical axis marker mirror (4) of the front optical-mechanical system, thus completing the optical axis registration between the auxiliary optical calibration component and the front optical-mechanical system. C. The second test light passes through the second 45° reflector (10), the second parallel plate (11), and the electrically controlled folding mirror (13) and is incident on the optical axis marker mirror (5) of the rear optical-mechanical system. After being reflected by the optical axis marker mirror (5), it passes through the electrically controlled folding mirror (13), the second parallel plate (11), and the second 45° reflector (10) and returns to the autocollimator (12). The autocollimator (12) displays the optical axis marker mirror (4) of the front optical-mechanical system and the optical axis marker mirror (5) of the rear optical-mechanical system. The angle difference of the returned signal is the optical axis angle deviation between the front optical engine system and the rear optical engine system. Adjust the pitch angle and azimuth angle of the electrically controlled folding mirror (13) so that the test light split by the second 45° reflector (10) passes through the second parallel plate (11), then through the electrically controlled folding mirror (13), and reaches the test light returned by the optical axis marker mirror (5) of the rear optical engine system. The test light returned by the optical axis marker mirror (4) of the front optical engine system coincides with the test light returned by the optical axis marker mirror (4) of the front optical engine system, thus completing the registration of the optical axes of the front and rear optical engine systems.

2. The method according to claim 1, characterized in that: The optical path of the pre-optical-mechanical system is sequentially provided with a primary mirror (1), a secondary mirror (2), a third mirror (3), and a pre-optical-mechanical system optical axis marker mirror (4); the optical path of the rear-optical-mechanical system is sequentially provided with an electrically controlled folding mirror (13), a rear-optical-mechanical system optical axis marker mirror (5), a converging mirror (6), and a detector (7).

3. The method according to claim 1, characterized in that: The electrically controlled folding mirror (13) is a motor-controlled reflector that rotates in two dimensions: pitch and azimuth. The controlled angle rotation accuracy is 1 second. The two test signals returned by the autocollimator (12) send control commands to the control motor of the electrically controlled folding mirror (13), so that it drives the electrically controlled folding mirror (13) to make precise adjustments to the pitch and azimuth angles until the test light signal returned by the optical axis marker mirror (4) of the front optical-mechanical system and the test light signal returned by the optical axis marker mirror (5) of the rear optical-mechanical system are completely superimposed, that is, the optical axis directions marked by the two marker mirrors are consistent.

4. The method according to claim 1, characterized in that: The first parallel plate (8) and the second parallel plate (11) have an aperture of 20 mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the surface coating near the first 45° reflector (9) and the second 45° reflector (10) has a 532 nm transmittance of 70% ± 5%, and the coating on the other side has a 532 nm transmittance of better than 98%; Its transmission wavefront is better than 1 / 50 of the wavelength, with a wavelength of 532nm.

5. The method according to claim 1, characterized in that: The first 45° reflector (9) and the second 45° reflector (10) have an aperture of 30 mm; the parallelism of the front and rear surfaces is better than 0.5 seconds; the included angle between them is 90°, and the assembly and adjustment ensure that the included angle is 90°±0.5 seconds; the front and rear surfaces are coated with aluminum reflective film, and the film is applied close to the first parallel plate (8) and the second parallel plate (11). The reflectivity of 532 nm is better than 97% when measured at 45°. The other side is coated with film, and the reflectivity of 633 nm is better than 97% when measured at 45°; its reflected wavefront is better than 1 / 50 wavelength when measured at 45°, and the wavelength is 532 nm.

6. The method according to claim 1, characterized in that: Before step A, there is also an inspection step for the auxiliary optical calibration components, specifically: The test light emitted from the collimator (12) is split into two beams after passing through the first 45° reflector (9) and the second 45° reflector (10). One beam of test light reaches the front surface of the first parallel plate (8), and nearly 30% of the beam is reflected back to the collimator (12). The other beam of test light reaches the front surface of the second parallel plate (11), and nearly 30% of the beam is reflected back to the collimator (12). The two beams overlap. The two beams are blocked respectively, and the angle between the two returning beams is measured. If the angle difference is less than 1 second, the auxiliary optical calibration component is considered to meet the test requirements.

7. The method according to claim 1, characterized in that: Before step A, there is also a process of optical axis registration and optical calibration of the front and rear optical engine systems. Specifically, the auxiliary optical calibration component is placed in the docking optical path between the front and rear optical engine systems, and the autocollimator (12) is placed outside the front and rear optical engine systems, and the optical axis of the test beam emitted by the autocollimator (12) is perpendicular to the docking optical path of the front and rear optical engine systems.

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