Off-axis collimator system with self-correcting function

Abstract

This invention relates to an off-axis collimator system with self-calibration function, comprising: a light source, a beam splitter, an off-axis secondary mirror, an off-axis primary mirror, and a reflector assembly arranged sequentially along the output light path of the collimator. Part of the light emitted from the light source passes through the beam splitter and is subsequently reflected by the off-axis secondary mirror and the off-axis primary mirror to form a parallel beam output. The position of the light source in a plane perpendicular to its emitted light is adjustable. A photodetector is disposed on the reflective light path of the beam splitter. The reflector assembly can be moved into or out of the output light path. When the reflector assembly is on the light path, the output light is parallel reflected by the reflector assembly to form an input light with the opposite direction to the output light. The input light is subsequently reflected by the off-axis primary mirror and the off-axis secondary mirror, and a portion of it is reflected by the beam splitter into the photodetector. The reflector assembly of this application can construct a self-collimating closed-loop detection light path during calibration, enabling the detection and correction of optical axis deviation using only the optical structure of the collimator system itself, thus improving calibration efficiency.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more specifically to an off-axis collimator system with self-correction function. Background Technology

[0002] Off-axis collimators are common optical testing devices with three main functions: first, placing a target of a specific shape at the focal plane to provide the imaging system with an observation target at infinity, enabling optical axis detection and image quality observation; second, placing a photodetector at the focal plane to detect the optical axis of the input laser beam and test its optical image quality; and third, placing a laser source and lens at the focal plane to enable the collimator to output a collimated parallel beam. Typically, each collimator performs only one of these functions. The systems under test corresponding to these three functions are: an imaging system, a laser emission system, and a beam detection system. Integrated optoelectronic systems usually include all of these systems, requiring optical image quality detection and multi-axis consistency calibration for multiple different types of optical systems.

[0003] To simultaneously calibrate the laser emission system and the beam detection system, a beam splitter is typically used to create two equivalent focal planes on the collimator's focal plane. One focal plane houses the photodetector, and the other houses the laser source, thus satisfying both requirements simultaneously. However, after prolonged use, the optical axes of the laser source and the photodetector may deviate. Traditional methods require repeated calibration using an external reference light source, which is cumbersome and inefficient. Summary of the Invention

[0004] Based on the above description, the present invention provides an off-axis collimator system with self-calibration function to solve the problems of traditional methods that require repeated calibration through an external reference light source, which is cumbersome and inefficient.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This application provides an off-axis collimator system with self-calibration function, comprising: A light source, a beam splitter, an off-axis secondary mirror, an off-axis primary mirror, and a reflecting component are arranged sequentially along the output light path of the collimator. The light emitted from the light source passes through the beam splitter and is reflected sequentially by the off-axis secondary mirror and the off-axis primary mirror to form a parallel beam output. The position of the light source in a plane perpendicular to its emitted light is adjustable. A photodetector is disposed on the reflected light path of the beam splitter; The reflective component can be moved into or out of the output light path. When the reflective component is in the light path, the output light is reflected parallel by the reflective component to form input light in the opposite direction to the output light. The input light is reflected sequentially by the off-axis primary mirror and the off-axis secondary mirror, and part of it is reflected by the beam splitter into the photodetector.

[0006] Preferably, the reflective component includes a first reflector and a second reflector. The first reflector is located on the optical path of the light emitted from the second reflector. When the reflective component is on the optical path of the output light, the output light is reflected sequentially by the first reflector and the second reflector to form the input light.

[0007] Preferably, the light source can move in a first direction and a second direction perpendicular to its emitted light, respectively, with the first direction and the second direction being perpendicular.

[0008] Preferably, the position of the light source is adjusted using a two-dimensional adjustment platform.

[0009] Preferably, the off-axis secondary mirror and the off-axis primary mirror are fixedly connected to each other.

[0010] Preferably, the off-axis primary mirror and the off-axis secondary mirror are fixedly connected by a connecting rod.

[0011] Preferably, both the off-axis secondary mirror and the off-axis primary mirror are mounted on the base, the off-axis primary mirror is fixed to the base, and the off-axis secondary mirror can move axially relative to the base on the connecting rod.

[0012] Preferably, the linear expansion coefficient of the connecting rod is less than that of the base.

[0013] Preferably, the off-axis secondary mirror is mounted on the base via a slide rail.

[0014] Preferably, the connecting rod is made of Invar steel.

[0015] Compared with the prior art, the technical solution of this application has at least the following beneficial technical effects: 1. This application constructs a complete self-collimating closed-loop detection optical path by sequentially arranging a light source, beam splitter, off-axis secondary mirror, off-axis primary mirror, and a reflective component that can be moved into or out of the optical path along the output light path, and placing a photodetector on the reflective optical path of the beam splitter. The position of the light source in the plane perpendicular to its emitted light is adjustable. When the reflective component moves into the optical path, the output light is reflected back along the original path to form the input light. The input light is then reflected again by the off-axis primary mirror and off-axis secondary mirror and guided by the beam splitter to the photodetector. When a deviation occurs in the optical axis of the laser source and the photodetector, the reflective component moves into the optical path, and the photodetector detects the positional deviation of the light spot from the target center. The operator or control system adjusts the two-dimensional position of the light source in the plane according to this deviation, bringing the light spot back to the target center, thus completing the optical axis correction. This solution requires no disassembly of the equipment or external auxiliary instruments; it utilizes only the optical structure of the collimator system itself to complete the detection and correction of optical axis deviation, simplifying the calibration process, improving calibration efficiency, and reducing maintenance costs.

[0016] 2. The light source can move in a first direction and a second direction that are perpendicular to and mutually perpendicular to its emitted light, and its position can be adjusted through a two-dimensional adjustment platform. This allows the two-dimensional position of the light source's emission point within the focal plane to be independently and precisely controlled. It can be used in conjunction with a photodetector to form a closed-loop feedback control system. When the detector detects that the light spot deviates from the center of the target surface, the control system can drive the light source to generate corresponding displacement compensation in the first and second directions based on the two-dimensional deviation signal of the light spot, thereby achieving precise correction of the optical axis deviation. The correction process is more accurate and efficient.

[0017] 3. The off-axis secondary mirror and the off-axis primary mirror are fixedly connected to each other via a connecting rod, ensuring that the relative positional relationship between the two mirrors remains constant. This prevents relative displacement between the secondary and primary mirrors due to vibration, temperature changes, or loose assembly, providing a stable reference for the self-calibration function. The off-axis primary mirror is fixed to the base, while the off-axis secondary mirror is mounted on the base via a slide rail and can move axially relative to the base via the connecting rod. The linear expansion coefficient of the connecting rod is less than that of the base. When the ambient temperature changes, the thermal expansion of the base is greater than that of the connecting rod. This difference in expansion drives the off-axis secondary mirror to move axially along the slide rail, automatically compensating for optical axis misalignment caused by temperature changes. The connecting rod, made of Invar steel, has an extremely low coefficient of thermal expansion, suppressing its own thermal deformation and making the temperature compensation effect more precise and controllable. This self-compensation structure, combined with the two-dimensional adjustment mechanism of the light source, reduces optical axis deviation caused by temperature changes, lowers the calibration frequency, and improves the optical stability and environmental adaptability of the collimator in a wide temperature range. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an off-axis collimator system with self-calibration function provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the reflective component in an off-axis collimator system with self-correction function provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of the off-axis secondary mirror and the off-axis primary mirror on the base in an off-axis collimator system with self-correction function provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Light source; 11. Output lens; 2. Beam splitter; 3. Off-axis secondary mirror; 4. Off-axis primary mirror; 5. Photodetector; 6. Reflection assembly; 61. First reflector; 62. Second reflector; 7. Two-dimensional adjustment platform; 8. Base; 9. Connecting rod; 10. Slide rail. Detailed Implementation

[0020] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] It is understood that spatial relation terms such as "below," "under," "below," "below," "above," "above," etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below" or "below" of the other element or feature will be oriented "above" the other element or feature. Therefore, the exemplary terms "below" and "below" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0023] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0024] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0025] Reference Figure 1 As shown, this application provides an off-axis collimator system with self-correction function. The system includes a light source 1, a beam splitter 2, an off-axis secondary mirror 3, an off-axis primary mirror 4, a photodetector 5, and a reflective component 6.

[0026] ReferenceFigure 1 As shown, the light source 1, beam splitter 2, off-axis secondary mirror 3 and off-axis primary mirror 4 are arranged sequentially along the output light path of the collimator. The light emitted from the light source 1 passes through the beam splitter 2 and is reflected sequentially by the off-axis secondary mirror 3 and the off-axis primary mirror 4 to form a parallel beam output, which serves as the output light of the collimator.

[0027] Reference Figure 1 As shown, specifically, the light source 1 has an output lens 11, which outputs a light beam. The output lens 11 collimates the light emitted by the light source 1 and outputs the light beam, matching the optical parameters of the light beam with the collimator.

[0028] The photodetector 5 is set on one of the reflected light paths of the beam splitter 2. When the input light is parallel to the output light and opposite in direction, it is reflected by the off-axis primary mirror 4 and the off-axis secondary mirror 3 in sequence, and then part of it is reflected by the beam splitter 2 into the photodetector 5.

[0029] In the design, the beam splitter 2 is set at the focal plane of the collimator, and the transmission and reflection paths of the beam splitter 2 respectively form equivalent focal planes conjugate with the focal plane. The output lens 11 is set at the equivalent focal plane in the transmission path, and the photodetector 5 is set at the equivalent focal plane in the reflection path.

[0030] Through the above design, the collimator system can simultaneously provide output from a long focal length collimated light source and the function of long focal length optical axis detection, and can simultaneously detect and calibrate the laser emission system and the beam detection system.

[0031] To facilitate adjustment and calibration when there is a deviation between the optical axis of light source 1 and the optical axis of photodetector 5, light source 1 is configured to have an adjustable position in a plane perpendicular to its emitted light, and the position of output lens 11 is adjustable within the equivalent focal plane.

[0032] Reference Figure 1 As shown, specifically, during installation, the light source 1 can be mounted on the system base 8 via a two-dimensional adjustment platform 7. This two-dimensional adjustment platform 7 can control the precise movement of the light source 1 in a first direction and a second direction perpendicular to the emitted light from the light source 1. The first direction and the second direction are perpendicular.

[0033] In the design, the two-dimensional adjustment platform 7 can be a precision platform electrically controlled by a stepper motor, providing a hardware basis for the automatic adjustment of the position of the light source 1.

[0034] Reference Figure 1 As shown, the reflector 6 is located on the output light path of the collimator. Specifically, the off-axis primary mirror 4 and the reflector 6 are arranged sequentially along the output light path of the collimator.

[0035] Reference Figure 1As shown, the reflector 6 is designed to be movable into or out of the output light path. When the reflector 6 is in the light path, the output light is reflected parallel by the reflector 6 to form the input light in the opposite direction to the output light. After being reflected sequentially by the off-axis primary mirror 4 and the off-axis secondary mirror 3, part of the input light is reflected by the beam splitter 2 into the photodetector 5.

[0036] When the reflector 6 is removed from the optical path, the output light can be directly output for calibration of the external beam detection system. When the reflector 6 is moved into the optical path, the output light is reflected by the reflector 6 and returns along the original path to form the input light. The input light is reflected again by the off-axis primary mirror 4 and the off-axis secondary mirror 3 and then guided by the beam splitter 2 to the photodetector 5, forming a complete self-collimating closed-loop detection optical path.

[0037] When the optical axes of laser source 1 and photodetector 5 deviate, reflective component 6 moves into the optical path. Photodetector 5 can detect the positional deviation of the light spot from the target center. The operator or control system adjusts the two-dimensional position of source 1 in the plane according to this deviation, so that the light spot returns to the target center, thus completing the optical axis correction. The correction work does not require disassembly of the equipment or external auxiliary instruments. The detection and correction of optical axis deviation can be completed using only the system's own optical structure, simplifying the calibration process, improving calibration efficiency, and reducing maintenance costs.

[0038] The position of the light source 1 is adjusted by the two-dimensional adjustment platform 7, so that the two-dimensional position of the light emission point of the light source 1 within the focal plane can be independently and precisely controlled. It can be used in conjunction with the photodetector 5 to form a closed-loop feedback control system. When the detector detects that the light spot deviates from the center of the target surface, the control system can drive the light source 1 to generate corresponding displacement compensation in the first and second directions according to the two-dimensional deviation signal of the light spot, so as to achieve precise correction of the optical axis deviation. The correction process is more accurate and efficient.

[0039] The above design, combined with a control system and software algorithms, enables the automation of the calibration process. During the design phase, the angular resolution of the photodetector 5, i.e., the angle corresponding to one pixel in the image received by the photodetector 5, can be calculated based on the system's optical parameters. The two-dimensional adjustment platform 7 can be calibrated through testing to determine the change in beam angle corresponding to each step of its stepper motor. During calibration, the light emitted from the laser source 1 is reflected by the off-axis primary mirror 4 and off-axis secondary mirror 3 to form output light. The output light is then reflected by the reflector component 6 to form input light. The input light is reflected by the off-axis primary mirror 4, off-axis secondary mirror 3, and beam splitter 2, converging on the target surface of the photodetector 5. A circular spot can be observed on the video software. The difference between the centroid position of the spot and the center position of the target surface is read. Calculations yield the adjustment amount of the stepper motor on the two-dimensional adjustment platform 7. Driving the stepper motor allows the centroid of the spot to coincide with the theoretical position, thus completing the automatic calibration.

[0040] Reference Figure 2As shown, in this embodiment, the reflective component 6 includes a first reflector 61 and a second reflector 62. The first reflector 61 is located on the light path of the light emitted from the second reflector 62. When the reflective component 6 is on the light path of the output light, the output light is reflected sequentially by the first reflector 61 and the second reflector 62 to form the input light.

[0041] Specifically, both the first reflector 61 and the second reflector 62 are prisms, and the reflecting surfaces of the first reflector 61 and the second reflector 62 are arranged at 90°, so that the output light at any angle can be reflected in parallel as input light after being reflected by the two prisms.

[0042] In the design, the first reflector 61 and the second reflector 62 can be mounted as a mirror assembly on a platform, and the platform can be mounted on the system base 8 via a track, allowing the mirror assembly to be moved relative to the base 8 to enter or exit the output optical path. The specific movement of the mirror assembly into and out can be driven by an electric cylinder or a lead screw mechanism to achieve automated control.

[0043] Reference Figure 1 and Figure 3 As shown, in this embodiment, the light source 1, beam splitter 2, off-axis secondary mirror 3, off-axis primary mirror 4, photodetector 5, and reflector 6 are all mounted on the system base 8.

[0044] Reference Figure 1 and Figure 3 As shown, the off-axis secondary mirror 3 and the off-axis primary mirror 4 are fixedly connected to each other. The relative positional relationship between the two mirrors remains unchanged, avoiding relative displacement between the secondary and primary mirrors due to vibration, temperature changes, or loose assembly, thus providing a stable reference for the self-calibration function.

[0045] Specifically, in this embodiment, the off-axis primary mirror 4 and the off-axis secondary mirror 3 are fixedly connected by a connecting rod 9. Specifically, both ends of the connecting rod 9 are fixedly connected to the mirror chambers of the off-axis primary mirror 4 and the off-axis secondary mirror 3, respectively. The number of connecting rods 9 is designed according to needs; this embodiment illustrates two rods.

[0046] To reduce the relative displacement between the off-axis primary mirror 4 and the off-axis secondary mirror 3 caused by the deformation of the connecting rod 9 due to temperature changes, the connecting rod 9 is made of a material with a low coefficient of linear expansion, such as Invar. The connecting rod 9 has an extremely low coefficient of thermal expansion, which suppresses the thermal deformation of the connecting rod 9 itself.

[0047] To reduce the overall manufacturing cost of the system, the base 8 is made of ordinary steel, meaning the linear expansion coefficient of the connecting rod 9 is less than that of the base 8. Using a lower-cost material for the base 8 reduces overall costs. To prevent relative displacement between the off-axis primary mirror 4 and the off-axis secondary mirror 3 due to deformation of the base 8 caused by temperature changes, the off-axis primary mirror 4 is designed to be fixed to the base 8, while the off-axis secondary mirror 3 is designed to be movable relative to the base 8 along the connecting rod 9 axis.

[0048] Reference Figure 3 As shown, specifically in this embodiment, the off-axis secondary mirror 3 is mounted on the base 8 via a slide rail 10. The off-axis secondary mirror 3 can slide on the slide rail 10 to move relative to the base 8. At this time, when the ambient temperature changes, the deformation of the base 8 is greater than the deformation of the connecting rod 9. Since the off-axis secondary mirror 3 is connected to the base 8 via the slide rail 10, the difference in deformation will cause the off-axis secondary mirror 3 and the base 8 to move relative to each other, automatically compensating for the relative movement between the off-axis primary mirror 4 and the off-axis secondary mirror 3 caused by temperature changes. Furthermore, Invar is a low-expansion material and is less affected by temperature, so the spatial position change between the primary and secondary mirrors is small, and the system wavefront aberration can be controlled within the operating range.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An off-axis collimator system with self-calibration function, characterized in that, include: A light source (1), a beam splitter (2), an off-axis secondary mirror (3), an off-axis primary mirror (4), and a reflector (6) are arranged sequentially along the output light path of the collimator. The light emitted from the light source (1) passes through the beam splitter (2) and is reflected sequentially by the off-axis secondary mirror (3) and the off-axis primary mirror (4) to form a parallel beam output. The position of the light source (1) in the plane perpendicular to its emitted light is adjustable. A photodetector (5) is disposed on the reflected light path of the beam splitter (2); The reflective component (6) can be moved into or out of the output light path. When the reflective component (6) is in the light path, the output light is reflected parallel by the reflective component (6) to form an input light in the opposite direction to the output light. The input light is reflected sequentially by the off-axis primary mirror (4) and the off-axis secondary mirror (3), and part of it is reflected by the beam splitter (2) into the photodetector (5).

2. The off-axis collimator system with self-calibration function according to claim 1, characterized in that: The reflective component (6) includes a first reflector (61) and a second reflector (62). The first reflector (61) is located on the light path of the emitted light from the second reflector (62). When the reflective component (6) is on the light path of the output light, the output light is reflected sequentially by the first reflector (61) and the second reflector (62) to form the input light.

3. The off-axis collimator system with self-calibration function according to claim 1, characterized in that: The light source (1) can move in a first direction and a second direction that are perpendicular to its emitted light, respectively. The first direction and the second direction are perpendicular.

4. The off-axis collimator system with self-calibration function according to claim 3, characterized in that: The position of the light source (1) is adjusted by a two-dimensional adjustment platform (7).

5. The off-axis collimator system with self-calibration function according to claim 1, characterized in that: The off-axis secondary mirror (3) and the off-axis primary mirror (4) are fixedly connected to each other.

6. The off-axis collimator system with self-calibration function according to claim 5, characterized in that: The off-axis primary mirror (4) and the off-axis secondary mirror (3) are fixedly connected by a connecting rod (9).

7. The off-axis collimator system with self-calibration function according to claim 6, characterized in that: The off-axis secondary mirror (3) and the off-axis primary mirror (4) are both mounted on the base (8). The off-axis primary mirror (4) is fixed to the base (8). The off-axis secondary mirror (3) can move axially relative to the base (8) on the connecting rod (9).

8. The off-axis collimator system with self-calibration function according to claim 7, characterized in that: The linear expansion coefficient of the material of the connecting rod (9) is less than that of the material of the base (8).

9. The off-axis collimator system with self-calibration function according to claim 7, characterized in that: The off-axis secondary mirror (3) is mounted on the base (8) via a slide rail (10).

10. The off-axis collimator system with self-calibration function according to claim 6, characterized in that: The connecting rod (9) is made of Invar steel.

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