Device and method for measuring locking precision of fast reflector in vibration environment

Abstract

The invention relates to the technical field of optical measurement, in particular to a device and method for measuring the locking precision of a fast reflector in a vibration environment, and the device mainly comprises a light spot generator, a fast reflector system, a standard mirror, a high-speed camera, a switching power supply, a fast reflector vibration tool, an image collection card, and a data processing unit. The light spot generator emits light beams which are respectively irradiated on the fast reflecting mirror body and the standard mirror, the high-speed camera captures the light beams reflected by the fast reflecting mirror body and the standard mirror, images are formed on the high-speed camera, the image acquisition card transmits light spots captured by the high-speed camera, and the data processing unit processes the transmitted images. The method is used for solving the problems that an existing measurement method is accurate in measurement result, complex in test system building, high in measurement method cost, difficult in real-time dynamic measurement and the like, and high-precision and real-time dynamic measurement of the vibration locking precision of the fast reflecting mirror is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical measurement, and particularly relates to a measuring device and method for the locking accuracy of a fast steering mirror under a vibration environment. Background Art

[0002] As an optical element capable of quickly changing the beam direction, a fast steering mirror has the advantages of small moment of inertia, high positioning accuracy, and fast response speed, and is widely used in fields such as adaptive optical systems, optical communications, and lidar. Installing a fast steering mirror into an imaging optical path can effectively improve the imaging quality of the system. Therefore, as a key component in an optical system, the vibration locking accuracy of the fast steering mirror directly affects the performance of the entire optical system. For example, in an adaptive optical system, high-precision locking of the fast steering mirror under a vibration environment is the key to achieving precise correction of wavefront aberration, thereby ensuring imaging quality. Therefore, in order to verify and test the vibration locking accuracy of the fast steering mirror, its locking accuracy measurement method is particularly crucial.

[0003] Traditional methods for measuring the vibration locking accuracy of a fast steering mirror are contact measurement methods or optical interference measurement methods. The contact vibration locking accuracy measurement method can conveniently and quickly measure the approximate range where the accuracy lies, and the cost of building the measurement system is low. However, since this measurement method has physical contact with the fast steering mirror, it interferes with the movement of the fast steering mirror, reduces the dynamic performance of the fast steering mirror, and thus affects the measurement accuracy, and cannot accurately reflect the vibration locking accuracy of the fast steering mirror. The measurement method based on optical interference can also reflect the locking accuracy. However, since this measurement method is easily interfered by environmental factors such as temperature and light pressure, resulting in inaccurate measurement results, the measurement method is complex to build and requires high equipment costs. At the same time, since this method takes an interferometer as the core, it is difficult to achieve real-time dynamic measurement. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and propose a measuring device and method for the locking accuracy of a fast steering mirror under a vibration environment, which can achieve high-precision and real-time dynamic measurement of the vibration locking accuracy of the fast steering mirror.

[0005] To achieve the above purpose, the present invention adopts the following specific technical solutions: The measuring device for the locking accuracy of a fast steering mirror under a vibration environment provided by the present invention includes a light spot generator, a switching power supply, a fast steering mirror vibration tooling, a fast steering mirror, a reference mirror, a high-speed camera, a first adjustment bracket, an image acquisition and data processing unit, a second adjustment bracket, and a vibration table; The fast steering mirror and the reference mirror are fixedly installed on the fast steering mirror vibration tooling so that the fast steering mirror and the reference mirror are in the same plane, and the fast steering mirror vibration tooling is fixedly installed on the vibration table; The spot generator is installed on the second adjustment bracket, and the high-speed camera is installed on the first adjustment bracket. By adjusting the angles of the first adjustment bracket and the second adjustment bracket, the light beam emitted by the spot generator is irradiated on the fast mirror and the reference mirror, and the light beams reflected by the fast mirror and the reference mirror are imaged on the high-speed camera; The switching power supply is connected to the fast mirror for power supply; the image acquisition and data processing unit is connected to the high-speed camera, receives the spot images captured by the high-speed camera and performs data processing, and obtains the locking accuracy of the fast mirror at different moments during the vibration according to the change of the center position of the spot reflected by the fast mirror and the reference mirror.

[0006] The present invention also provides a method for measuring the locking accuracy of a fast mirror in a vibration environment. Using the above measurement device, it includes the following steps: S1. Build a measurement device for the locking accuracy of a fast mirror in a vibration environment; S2. When the vibration table is in a stationary state, start the spot emitter. The high-speed camera captures the spots reflected by the fast mirror and the reference mirror respectively. The image acquisition and data processing unit saves the initial positions of the two spots as the reference values for calculating the vibration locking accuracy in the follow-up; After the vibration table is started, the fast mirror and the reference mirror vibrate under the set vibration conditions. The high-speed camera and the connected image acquisition and data processing unit collect the image positions of the spots reflected by the fast mirror and the reference mirror respectively during the vibration in real time; S3. The image acquisition and data processing unit uses a feature extraction algorithm to identify and determine the center position coordinates of the spots reflected by the fast mirror and the reference mirror respectively in each frame of the image; According to the change of the center position coordinates of the spots reflected by the fast mirror and the reference mirror respectively in the images at different moments, calculate the pixel amount corresponding to the relative position change of the two spots. Since the motion state of the reference mirror can be used as a reference benchmark, by comparing the position change of the spot reflected by the fast mirror relative to the spot reflected by the reference mirror, the locking accuracy of the fast mirror at different moments during the vibration is calculated.

[0007] Further, in step S3, the image acquisition and data processing unit extracts the spot features by the gray centroid method, accurately calculates the center coordinates P1n(X1n, Y1n) and P2n(X2n, Y2n) of the spots reflected by the fast mirror and the reference mirror respectively in each frame of the image, and calculates the pixel amount Pn(x, y) corresponding to the relative position change of the two according to the change of the center position coordinates of the two spots in the images at different moments. The pixel amount Pnx corresponding to the relative position change in the horizontal direction = X1n - X2n, and the pixel amount Pny corresponding to the relative position change in the vertical direction = Y1n - Y2n; Actual relative deflection angles Δθxn in the horizontal direction and Δθyn in the vertical direction: , ; α is the angle corresponding to 1 pixel; Measure N frames of collected images. The horizontal and vertical angle deviations obtained each time are Δθxn and Δθyn. Calculate the average value of the horizontal angle deviation and the average value of the vertical angle deviation , which can measure the average level of the vibration locking accuracy of the fast steering mirror; Calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion. The smaller the value, the more stable the locking accuracy. The formula is: ; .

[0008] Furthermore, the pixel size of the high-speed camera CCD is 3um×3um, and the focal length F = 1m. The calculation formula for the angle α corresponding to 1 pixel is: ; Actual relative deflection angles Δθxn in the horizontal direction and Δθyn in the vertical direction, unit: urad: , .

[0009] The present invention can achieve the following technical effects: 1. The measurement process of the present invention is less affected by environmental factors and can achieve stable measurement in a relatively complex working environment. A high-power spot generator is selected to simulate the beam irradiation at infinity, reducing the error introduced by the light source. Image acquisition is performed by combining a high-speed camera and an image acquisition card to reduce beam attenuation. At the same time, the universality of the test system is improved. Using the spot reflection principle, acquisition is completed only after one reflection.

[0010] 2. It can significantly improve the measurement accuracy of the vibration locking accuracy. By simultaneously irradiating the fast steering mirror and the reference mirror with a large-sized spot to ensure the consistency of the light source, the reference mirror is fixed on the vibration fixture of the fast steering mirror, so that the distance between the fast steering mirror and the reference mirror is close enough to ensure that the same beam of light source can irradiate both mirror surfaces simultaneously. Measure the spots reflected by the fast steering mirror and the reference mirror, and analyze the state of the spot reflected by the fast steering mirror with the spot reflected by the reference mirror as a reference. This method effectively reduces the measurement error and significantly improves the measurement accuracy of the vibration locking accuracy of the fast steering mirror by adding a reference benchmark and placing the reference benchmark and the fast steering mirror to be measured under the same test conditions.

[0011] 3. It is applicable to the measurement of the locking accuracy of fast mirrors under various vibration conditions and has broad application prospects. Based on the data processing method of the image analysis algorithm, it can quickly and accurately calculate the change in the spot position and the locking accuracy, improving the measurement efficiency. At the same time, by analyzing the spot reflected by the standard mirror, it is possible to further determine the current vibration level and various vibration conditions, improving the accuracy of the measurement of the locking accuracy of fast mirrors and expanding the measurement range.

[0012] 4. It is applicable to the measurement of the locking accuracy of fast mirrors operating at different angles. At the same time, the method of the present invention solves the problem that under vibration conditions, it is impossible to measure the locking error of fast mirrors at high frequencies. According to this measurement method, by setting the fast mirror at different working angles, the locking accuracy at different working angles can be determined, simulating its actual working state, and objectively and accurately evaluating the actual performance of the fast mirror. By high-speed camera high-frequency acquisition of the relative position change of the spot reflected by the fast mirror and the spot reflected by the standard mirror, the performance of the fast mirror under vibration can be more accurately evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of a measurement device for the locking accuracy of a fast mirror in a vibration environment according to an embodiment of the present invention.

[0014] The reference numerals therein include: Spot generator 1, switching power supply 2, fast mirror vibration tooling 3, fast mirror 4, standard mirror 5, high-speed camera 6, first adjustment bracket 7, image acquisition and data processing unit 8, second adjustment bracket 9, vibration table 10. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.

[0016] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and do not constitute a limitation to the present invention.

[0017] An embodiment of the present invention provides a measurement device for the locking accuracy of a fast mirror in a vibration environment, and its structure is as Figure 1 shown, including a spot generator 1, a switching power supply 2, a fast mirror vibration tooling 3, a fast mirror 4, a standard mirror 5, a high-speed camera 6, a first adjustment bracket 7, an image acquisition and data processing unit 8, a second adjustment bracket 9, and a vibration table 10.

[0018] The fast steering mirror 4 and the reference mirror 5 are fixedly installed on the fast steering mirror vibration tooling 3, such that the fast steering mirror 4 and the reference mirror 5 are in the same plane, and the fast steering mirror vibration tooling 3 is fixedly installed on the vibration table 10.

[0019] The light spot generator 1 is installed on the second adjustment bracket 9, and the high-speed camera 6 is installed on the first adjustment bracket 7. By adjusting the angles of the first adjustment bracket 7 and the second adjustment bracket 9, the light beam emitted by the light spot generator 1 is irradiated on the fast steering mirror 4 and the reference mirror 5, and the light beam reflected by the fast steering mirror 4 and the reference mirror 5 is captured by the high-speed camera 6 and imaged on the high-speed camera 6.

[0020] The switching power supply 2 is connected to the fast steering mirror 4 and supplies power to the fast steering mirror 4 through an external power cord; the image acquisition and data processing unit 8 is connected to the high-speed camera 6, receives the light spot images captured by the high-speed camera 6 and performs data processing, and obtains the locking accuracy of the fast steering mirror 4 at different moments during vibration according to the change in the center position of the light spots reflected by the fast steering mirror 4 and the reference mirror 5.

[0021] In order for this measurement system to be able to test the vibration locking accuracy of fast steering mirrors of different types and different sizes and improve the versatility of the measurement system, the light spot generator 1 is selected to emit a large light spot beam, simulating parallel light beams emitted from infinity and irradiating the fast steering mirror 4 and the reference mirror 5 at the same time. Therefore, the reference mirror 5 used as the measurement reference is installed on the fast steering mirror vibration tooling 3, shortening the distance between the fast steering mirror 4 and the reference mirror 5 to meet the requirement of irradiating the fast steering mirror 4 and the reference mirror 5 with the same light source at the same time.

[0022] To reduce the requirements of the test system for the test environment, the light spot is only reflected once by the fast steering mirror 4 and the reference mirror 5 and then imaged by the high-speed camera 6. To improve the accuracy of the measurement system, the high-speed camera 6 is selected to capture the light spot reflected by the reference mirror 5, and this light spot is used as the reference benchmark to determine the vibration locking accuracy of the fast steering mirror 4 under vibration conditions. At the same time, the current vibration level can also be obtained according to the reflected light spot of the reference mirror 5 to further accurately measure the vibration environment.

[0023] The embodiment of the present invention also provides a method for measuring the locking accuracy of a fast steering mirror under a vibration environment, using the above measurement device, and the specific steps are as follows: S1. Build a measurement device for the locking accuracy of a fast steering mirror under a vibration environment.

[0024] (1) Install the fast steering mirror 4 on the fast steering mirror vibration tooling 3, and bond the reference mirror 5 to the front end face of the fast steering mirror vibration tooling 3, ensuring that the fast steering mirror 4 and the reference mirror 5 are in the same plane and their relative positions are fixed, and then fasten the fast steering mirror vibration tooling 3 to the vibration table 10.

[0025] (2) Start the switching power supply 2 to supply power to the fast steering mirror 4 to ensure that the fast steering mirror 4 is in the working state. Send commands through the host computer software to lock the fast steering mirror 4 at the initial zero position to determine the initial zero position locking state. Send position commands through the host computer software to simulate the deflection positions required by the fast steering mirror 4 in applications to determine the actual position locking state.

[0026] (3) Install the light spot generator 1 and the high-speed camera 6. Adjust the position and angle of the light spot generator 1 through the second adjustment bracket 9, and adjust the position and angle of the high-speed camera 6 through the first adjustment bracket 7 so that the emitted light beam can be reflected by the fast steering mirror 4 and the reference mirror 5 to the effective shooting area of the high-speed camera 6. Set parameters for the high-speed camera 6 and the image acquisition and data processing unit 8, and perform automatic calibration to ensure the accuracy of image acquisition. Set the focal length of the high-speed camera 6 to 1m, the frame rate to 1KHz, and the resolution to 1920*1080. At the same time, perform initialization settings on the image acquisition card to ensure clear and stable images.

[0027] S2. Measurement process: In the stationary state of the vibration table 10, ensure that the test environment is set up. Start the light spot emitter 1 and save the initial positions of the first light spot and the second light spot reflected by the fast steering mirror 4 and the reference mirror 5 as the reference values for subsequent calculation of the vibration locking accuracy.

[0028] Start the vibration table to vibrate the fast steering mirror 4 and the reference mirror 5 under the set vibration conditions. The high-speed camera 6 collects the image sequences of the first light spot reflected by the fast steering mirror 4 and the second light spot reflected by the reference mirror during vibration through the image acquisition and data processing unit 8.

[0029] S3. The image acquisition and data processing unit 8 uses the feature extraction algorithm to identify and determine the central position coordinates of the first light spot and the second light spot in each frame of the image. According to the changes in the central position coordinates of the first light spot and the second light spot in the images at different times, calculate the pixel amount Pn(x, y) corresponding to the relative position change between the two. Since the motion state of the reference mirror 5 can be used as a reference benchmark, by comparing the position changes of the first light spot relative to the second light spot, the locking accuracy of the fast steering mirror at different times during vibration can be calculated.

[0030] The image acquisition and data processing unit 8 processes the collected image data using image analysis software. First, extract the light spot features through the gray center of gravity method, and accurately calculate the central coordinates P1n(X1n, Y1n) and P2n(X2n, Y2n) of the first light spot and the second light spot in each frame of the image. The pixel size of the high-speed camera CCD is 3um*3um, and the number of pixels in the length and width directions is 1920 and 1080. The focal length of the high-speed camera 6 is 1m.

[0031] By collecting the change in the center position of the second light spot, calculate the pixel amount P(x, y) corresponding to the change amount. By analyzing the position change amount per unit time and taking the second derivative, obtain the acceleration amount of the second light spot, and then obtain the current vibration level. According to the change in the center position coordinates of the first light spot and the second light spot in the images at different times, calculate the pixel amount Pn(x, y) corresponding to the relative position change between the two.

[0032] Let the center position coordinates of the first light spot at a certain moment be (X1n, Y1n), and the center position coordinates of the second light spot at the same moment be (X2n, Y2n). Then: the pixel amount Pnx corresponding to the relative position change amount in the horizontal direction = X1n - X2n, and the pixel amount Pny corresponding to the relative position change amount in the vertical direction = Y1n - Y2n. Since the motion state of the standard mirror can be used as a reference benchmark, by comparing the position change of the first light spot relative to the second light spot and combining the 6 parameters of the high-speed camera, calculate the locking accuracy of the fast steering mirror 4 during vibration.

[0033] Given that the pixel size of the high-speed camera CCD is 3um × 3um and the focal length of the camera is F = 1m, according to the principle of geometric optics, the angle α (unit: rad) corresponding to 1 pixel can be calculated by the following formula: Substitute F = 1m to get From this, the actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction can be calculated, unit: urad: , ; Measure N frames of collected images. The horizontal and vertical angle deviations obtained each time are Δθxn and Δθyn (n = 1, 2, 3..., N). Calculate the average value of the horizontal angle deviation and the average value of the vertical angle deviation which can measure the average level of the vibration locking accuracy of the fast steering mirror 4; calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion. The smaller the value, the more stable the locking accuracy. The formula is: , 。

[0034] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0035] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0036] The above specific implementation manners of the present invention do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A device for measuring the locking accuracy of a fast reflector under vibration conditions, characterized in that: It comprises a light spot generator (1), a switching power supply (2), a fast reflector vibration tooling (3), a fast reflector (4), a standard mirror (5), a high-speed camera (6), a first adjustment frame (7), an image acquisition and data processing unit (8), a second adjustment frame (9), and a vibration table (10); The fast reflection mirror (4) and the standard mirror (5) are fixedly mounted on the fast reflection mirror vibration fixture (3) so that the fast reflection mirror (4) and the standard mirror (5) are located in the same plane, and the fast reflection mirror vibration fixture (3) is fixedly mounted on the vibration table (10); The light spot generator (1) is mounted on the second adjustment frame (9), and the high-speed camera (6) is mounted on the first adjustment frame (7). By adjusting the angles of the first adjustment frame (7) and the second adjustment frame (9), the light beam emitted by the light spot generator (1) is irradiated on the fast reflection mirror (4) and the standard mirror (5), and the light beam reflected by the fast reflection mirror (4) and the standard mirror (5) is imaged on the high-speed camera (6); The switch power supply (2) is connected to the fast reflector (4) for power supply; the image acquisition and data processing unit (8) is connected to the high-speed camera (6), receives the light spot image captured by the high-speed camera (6) and performs data processing, and obtains the locking accuracy of the fast reflector at different times during the vibration process according to the change of the center position of the light spot reflected by the fast reflector (4) and the standard mirror (5).

2. A method for measuring the locking accuracy of a fast reflector under a vibration environment, using the measuring device according to claim 1, characterized in that: The steps include: S1. Build a device to measure the locking accuracy of a fast mirror under vibration conditions; S2, when the vibration table (10) is in a stationary state, the light spot emitter (1) is started, the high-speed camera (6) captures the light spots reflected by the fast reflection mirror (4) and the standard mirror (5), respectively, and the image acquisition and data processing unit (8) saves the initial positions of the two light spots as reference values ​​for subsequent calculation of the vibration locking accuracy; After the vibration table (10) is started, the fast reflection mirror (4) and the standard mirror (5) are vibrated under set vibration conditions, and the high-speed camera (6) and the connected image acquisition and data processing unit (8) collect the image positions of the light spots reflected by the fast reflection mirror (4) and the standard mirror (5) respectively during the vibration process in real time; S3, the image acquisition and data processing unit (8) identifies and determines the center position coordinates of the light spots reflected by the fast reflection mirror (4) and the standard mirror (5) in each frame of the image through a feature extraction algorithm; According to the changes in the center position coordinates of the light spots reflected by the fast reflection mirror (4) and the standard mirror (5) in the images at different times, the number of pixels corresponding to the relative position changes of the two light spots is calculated. Since the motion state of the standard mirror (5) can be used as a reference, the locking accuracy of the fast reflection mirror (5) at different times during the vibration process is calculated by comparing the position changes of the light spots reflected by the fast reflection mirror (4) with those of the light spots reflected by the standard mirror (5).

3. The method for measuring locking accuracy of a fast reflector under a vibration environment according to claim 2, characterized in that: In step S3, the image acquisition and data processing unit (8) extracts the light spot features by using the grayscale centroid method, accurately calculates the center coordinates P1n (X1n, Y1n) and P2n (X2n, Y2n) of the light spots reflected by the fast reflector (4) and the standard mirror (5) in each frame of the image, respectively, and calculates the pixel quantity Pn (x, y) corresponding to the relative position change of the two light spots according to the change of the center position coordinates of the two light spots in the image at different times, the pixel quantity Pnx corresponding to the relative position change in the horizontal direction is Pnx=X1n-X2n, and the pixel quantity Pny corresponding to the relative position change in the vertical direction is Pny=Y1n-Y2n; The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction are: Δθxn=α×Pnx, Δθyn=α×Pny; α is the angle corresponding to 1 pixel; Measure the collected N frames of images, and the horizontal and vertical angle deviations obtained in each measurement are Δθxn and Δθyn. Calculate the average horizontal angle deviation and the average vertical angle deviation , which can measure the average level of the vibration locking accuracy of the fast reflector; calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion. The smaller the value, the more stable the locking accuracy. The formula is: ； 。 4. The method for measuring locking accuracy of a fast reflector under a vibration environment according to claim 3, characterized in that: The CCD pixel size of the high-speed camera (6) is 3um×3um, the focal length is F=1m, and the angle α corresponding to 1 pixel is calculated as: ; The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction, unit: urad: ， 。

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