A wide-range high-precision precise angle measuring method and mechanism

Abstract

The application provides a wide-range high-precision precise angle measuring mechanism and method, which utilizes charge coupled element light spot centroid detection and four-quadrant photoelectric detector phase detection technology to realize accurate measurement of light beam direction, and can obtain angle deviation of laser in a large range. The high-precision precise angle measuring mechanism and method provided by the application have simple structure, large measurement range and accurate angle measurement, and have wide application prospect in the field of precise measurement.

Description

Technical Field

[0001] This invention relates to the field of laser detection technology, specifically to a wide-range, high-precision angle measurement method and mechanism. Background Technology

[0002] With the increasing demand for high-precision angle measurement in fields such as medicine and aerospace, high-accuracy micro-angle measurement technology has become a key focus of scientific research in various countries. To achieve higher angle measurement accuracy, numerous micro-angle measurement principles and methods have been proposed. Simultaneously improving both the angle measurement range and accuracy is now one of the most pressing issues to be addressed.

[0003] Micro-angle measurement technology plays a crucial role in modern scientific research and industrial production. However, existing measurement methods suffer from several limitations, such as limited measurement range and low accuracy. Traditional charge-coupled device (CCD) cameras offer a relatively large field of view, but their measurement accuracy is limited, only reaching the micro-radian level. While differential wavefront sensing technology using a four-quadrant detector can calculate angle information down to the nano-radian level, the small field of view of the four-quadrant detector makes it difficult for the laser to be measured to directly enter its field of view. Therefore, there is a current need for a laser angle measurement system that is simple in structure, has a large measurement range, high accuracy, and high reliability. Summary of the Invention

[0004] This invention mainly uses a two-stage detection system of charge-coupled devices and four-quadrant detectors to measure the deviation angle of the object under test. Combining the advantages of the large field of view of the charge-coupled devices and the accurate measurement of the four-quadrant detectors, it can achieve high-precision angle measurement over a wide range.

[0005] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0006] A large-range, high-precision angle measuring mechanism includes a laser, a first beam splitter, a first reflector, a second beam splitter, a third beam splitter, an aperture, a second reflector, a charge-coupled device (CCD) camera, a third beam splitter, a four-quadrant detector, a phase meter, and a processor arranged sequentially along the optical path. The first beam splitter reflects the laser emitted from the laser to the fourth beam splitter and transmits it to the first reflector. The reflecting prism reflects the laser to the second beam splitter, the second beam splitter reflects the laser to the third beam splitter, the third beam splitter reflects the laser reflected back from the second reflector to the CCD camera and transmits it to the second beam splitter. The fourth beam splitter transmits the light transmitted through the fourth beam splitter to the four-quadrant detector.

[0007] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0008] As a preferred embodiment of the present invention: The charge-coupled device (CCD) camera receives the laser light reflected from the third beam splitter, forming a light spot image on the surface, which is then transmitted to the processor. Based on the light spot image transmitted by the CCD camera, the processor uses a light spot centroid detection algorithm to calculate the offset of the light spot from the center of the CCD camera, thereby calculating the corresponding yaw and pitch angles. The processor controls the movement of the six-degree-of-freedom platform according to the yaw and pitch angles, adjusting the light spot received by the CCD camera to the center of the CCD camera.

[0009] As a preferred technical solution of the present invention: the four-quadrant detector receives the laser reflected and transmitted by the fourth beam splitter and interferes on the surface of the four-quadrant detector. The four-quadrant detector detects the beat frequency term of the interference signal. The phase meter simultaneously performs phase calculation on the interference signals in the four quadrants. The processor uses the phase difference between the upper and lower quadrants and the left and right quadrants to calculate the yaw angle and pitch angle at this time.

[0010] As a preferred technical solution of the present invention: the processor adds the yaw angle and pitch angle calculated by the two detectors to obtain the total yaw angle and pitch angle.

[0011] Compared with the prior art, the wide-range, high-precision angle measurement method and mechanism provided by the present invention have the following beneficial effects:

[0012] 1. Large measurement range: Due to the large field of view of the charge-coupled device camera, a large measurement range can be obtained.

[0013] 2. High measurement accuracy: Utilizing a differential wavefront sensing algorithm with a four-quadrant detector and a phase meter, a measurement accuracy of 10 nanoradians can be achieved.

[0014] 3. The structure is simple. It utilizes a combination of a charge-coupled device camera and a four-quadrant detector in a two-stage detector system, which expands the measurement range while maintaining a measurement accuracy in the 10 nanoradian range. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the high-precision angle measurement system of the present invention;

[0016] Figure 2 This is a flowchart of the high-precision angle measurement method of the present invention. Detailed Implementation

[0017] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Reference Figures 1 to 2A wide-range, high-precision angle measuring mechanism includes a laser 1-1, a first beam splitter 2-1, a reflector 3-1, a second beam splitter 2-2, a third beam splitter 2-3, an aperture 4-1, a second reflector 3-2, a charge-coupled device camera 5-1, a four-quadrant detector 6-1, a phase meter 7-1, and a processor 8-1.

[0019] Step 1: Attach the second reflector 3-2 to the surface of the object to be tested.

[0020] Step 2: Turn on the laser 1-1, so that the laser light passes through the first beam splitter 2-1, is transmitted to the first reflector 3-1, reflected to the second beam splitter 2-2, reflected to the third beam splitter 2-3, and after passing through the aperture 4-1, is reflected by the second reflector 3-2 to the third beam splitter 2-3, and is reflected by the third beam splitter 2-3 to the charge-coupled device camera 3-1, where the camera detects the laser spot image.

[0021] Step 3: The charge-coupled device camera 3-1 transmits the spot image to the external processor 8-1. The processor 8-1 uses the spot centroid detection algorithm to calculate the image on the charge-coupled device camera 3-1 and obtain the offset x and y of the spot from the center of the charge-coupled device camera.

[0022] in , .

[0023] Based on the offsets x and y and the equivalent focal length f of the mechanism, processor 8-1 calculates the yaw and pitch deviation angles, where , .

[0024] Step 4: Input the calculated yaw and pitch angles into the six-degree-of-freedom motion platform, causing the platform to rotate by these angles. This allows the laser reflected by the second reflector 3-2 to pass through the third beam splitter 2-3, the second beam splitter 2-2, and the fourth beam splitter 2-4, entering the field of view of the four-quadrant detector 6-1. If the laser does not enter the field of view of the four-quadrant detector, repeat steps 3 and 4.

[0025] Step 5: The laser reflected by the second reflector 3-2 enters the field of view of the four-quadrant detector 6-1. The laser from laser 1-1 is reflected by the first beam splitter 2-1 and the fourth beam splitter 2-4 into the four-quadrant detector 6-1, where it interferes with the laser from above. The four-quadrant detector 6-1 records the beat frequency term of the interference signal, and the phase meter 7-1 simultaneously calculates the phase of the signals in all four quadrants, recording the phase as... Phase meter 7-1 transmits the phase signal to external processor 8-1. The processor can calculate the phase signal using the difference between the upper and lower quadrants and the left and right quadrants of the four-quadrant detector 6-1. and .in , The yaw and pitch angles measured by the QPD can be obtained by utilizing the linear conversion relationship between phase difference and tilt angle. , .

[0026] Step 6: The processor adds the yaw and pitch angles measured on the CCD and QPD to obtain the total yaw and pitch angles.

[0027] Specifically, this is implemented through the following embodiments:

[0028] Reference Figure 1 The second reflector 3-2 is attached to the device under test. The laser emitted from laser 1-1 passes through various devices, including the first beam splitter 2-1, the first reflector 3-1, the first beam splitter 2-2, the third beam splitter 2-3, the aperture 4-1, the second reflector 3-2, the third beam splitter 2-3, and finally the charge-coupled device (CCD) camera 3-1. The camera detects the laser spot image. Based on the laser spot image detected by the CCD camera, processor 8-1 obtains a yaw angle of 13 μrad and a pitch angle of 24 μrad. Processor 8-1 controls the six-degree-of-freedom platform to adjust its attitude, compensating for the yaw and pitch angles, so that the laser spot reflected by the second reflector 3-2 enters the field of view of the four-quadrant detector 6-1. The four-quadrant detector 6-1 detects the beat frequency of the interference signal on the surface and records the beat frequency term of the interference signal. The phase meter 7-1 simultaneously calculates the phase of the signal in each of the four quadrants. The processor 8-1 uses the phase difference between the upper and lower quadrants and the left and right quadrants of the four-quadrant detector 6-1 to calculate the yaw angle of 710 nrad and the pitch angle of 130 nrad. The total yaw angle is 13.71 μrad, and the pitch angle is 24.12 μrad.

Claims

1. A method for large-scale, high-precision angle measurement, comprising the following steps: Step one: Set up a second reflector on the surface of the object to be measured. Step 2: Turn on the laser, so that the laser beam passes through the first beam splitter, is transmitted to the first reflector, reflected to the second beam splitter, reflected to the third beam splitter, and after passing through the aperture, is reflected by the second reflector to the third beam splitter, and is reflected by the third beam splitter to the charge-coupled device camera, where the camera detects the laser spot image. Step 3: The charge-coupled device (CCD) camera transmits the spot image to an external processor. The processor uses a spot centroid detection algorithm to calculate the offset x and y of the spot from the center of the CCD camera. in , Based on the offsets x and y and the equivalent focal length f of the mechanism, the processor calculates the yaw and pitch deviation angles, where , ,in Yaw angle The pitch angle; Step 4: Input the calculated yaw and pitch angles into the six-degree-of-freedom motion platform, causing the platform to rotate by the angles of the yaw and pitch angles, so that the laser reflected by the second reflector passes through the third beam splitter. The second and fourth beam splitters then enter the field of view of the four-quadrant detector. If they do not enter the field of view of the four-quadrant detector, repeat steps 3 and 4. Step five: The laser reflected by the second mirror enters the field of view of the four-quadrant detector. The laser beam is reflected by the first and fourth beam-splitting prisms and enters the four-quadrant detector, interfering with the laser beam above. The four-quadrant detector records the beat frequency term of the interference signal. Simultaneously, the phase meter calculates the phase of the signal in each of the four quadrants and records the phase as... The phase meter transmits the phase signal to an external processor, which calculates the phase value using the difference between the upper and lower quadrants and the left and right quadrants of the four-quadrant detector. and ,in, The phase difference is in the yaw direction. The phase difference is in the pitch direction; where , The yaw and pitch angles measured by the QPD are obtained by utilizing the linear conversion relationship between phase difference and tilt angle. , Where r is the radius of the four-quadrant detector. The wavelength at which the laser emits light; Step 6: The processor adds the yaw and pitch angles measured on the CCD and QPD to obtain the total yaw and pitch angles.

2. The angle measuring mechanism employing the wide-range, high-precision angle measuring method described in claim 1, characterized in that: The large-range, high-precision angle measurement mechanism includes a laser, a first beam splitter, a first reflector, a second beam splitter, a third beam splitter, an aperture, a second reflector, a charge-coupled device (CCD) camera, a fourth beam splitter, a four-quadrant detector, a phase meter, and a processor arranged sequentially along the optical path. The first beam splitter reflects the laser emitted from the laser to the fourth beam splitter and transmits it to the first reflector. The first reflector reflects the laser to the second beam splitter, and the second beam splitter reflects the laser to the third beam splitter. The third beam splitter reflects the laser reflected back from the second reflector one path to the CCD camera and another path to the second beam splitter. The fourth beam splitter transmits the light transmitted through the fourth beam splitter to the four-quadrant detector.

3. The wide-range, high-precision angle measuring mechanism as described in claim 2, characterized in that: The charge-coupled device (CCD) camera receives the laser reflected from the third beam splitter, forming a light spot image on the surface, which is then transmitted to the processor. Based on the light spot image transmitted by the CCD camera, the processor uses a light spot centroid detection algorithm to calculate the offset of the light spot from the center of the CCD camera, thereby calculating the corresponding yaw angle and pitch angle. The processor controls the movement of the six-degree-of-freedom platform based on the yaw angle and pitch angle to adjust the light spot received by the CCD camera to the center of the CCD camera.

4. The wide-range, high-precision angle measuring mechanism as described in claim 2, characterized in that: The four-quadrant detector receives the laser reflected and transmitted by the fourth beam splitter and interferes with the surface of the four-quadrant detector. The four-quadrant detector detects the beat frequency term of the interference signal, and the phase meter simultaneously performs phase calculation on the interference signals in the four quadrants. The processor uses the phase difference between the upper and lower quadrants and the left and right quadrants to calculate the yaw angle and pitch angle at this time.

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