Four-quadrant photoelectric detector test system and test method

Abstract

The invention discloses a four-quadrant photoelectric detector test system and method, the system comprises a light source, a three-dimensional translation stage, an optical system, a tested guide system, a measurement camera and an upper computer, a tested four-quadrant detector is installed on the tested guide system, and the tested four-quadrant detector and the tested guide system are fixed on a support of the three-dimensional translation stage; the optical system is used for splitting the light source, the light source firstly penetrates through the optical system to irradiate the surface of the detected four-quadrant detector, and meanwhile light reflected by the surface of the detected four-quadrant detector is received by the measuring camera after being reflected by the optical system; the measurement camera obtains an energy distribution image of the light spot, and the upper computer calculates a calibration coefficient based on light spot energy center offset information measured by the measurement camera and light spot energy center offset information output by the guide system. The linear relation between the light spot energy center offset and the output signal is tested and calibrated, the high-efficiency test requirement is met, and then the application capacity of the four-quadrant detector guide system is improved.

Description

Technical Field

[0001] The invention relates to a four-quadrant photoelectric detector test system and a test method, belonging to the technical field of test calibration. Background Art

[0002] A four-quadrant photodetector is a device consisting of four identically spaced photodetectors integrated into a single semiconductor substrate and arranged in a rectangular coordinate system. They offer fast response, high sensitivity, and a wide detection spectral range. Due to their unique rectangular arrangement, they are commonly used in laser guidance, laser alignment, and space optical communications. They also have widespread applications in precision lathe machining, large-scale 3D measurement, automotive manufacturing, aerospace, and other military and civilian fields.

[0003] The principle behind a four-quadrant detector in laser guidance applications is as follows: each quadrant of the detector outputs a current signal. Factors influencing the signal strength include the size of the light spot divided by the quadrants and the intensity of the light spot. Laser light reflected from the target is converged by an optical system and detected by the four-quadrant detector. The sum and difference of the current signals output by the four quadrants are then processed to determine the offset of the light spot center on the detector, i.e., the target's position relative to the detector.

[0004] However, in actual measurement, the calculation of X- and Y-axis offsets requires a calibration factor, K, to be incorporated into the calculation formula. This factor has multiple sources. First, it arises from the detection principle: the guidance system can have a certain deviation from the center of the detected light spot energy and unevenness in the detected light spot energy. Second, issues such as noise and dark current generated by the photodetection circuit and the ADC acquisition circuit can also lead to inaccurate data. Therefore, how to quickly measure and calibrate the four-quadrant detector guidance system is a pressing issue. Summary of the Invention

[0005] The purpose of the present invention is to provide a four-quadrant photoelectric detector testing system and testing method to realize the testing and calibration of the inconsistency between quadrants of the four-quadrant detector used in the guidance system, meet the high-efficiency testing requirements, improve the accuracy of the guidance system, and thus enhance the application capability of the four-quadrant detector guidance system.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a four-quadrant photoelectric detector test system, comprising: a light source, a three-dimensional translation stage, an optical system, a guide system to be tested, a measuring camera, and a host computer. The four-quadrant detector to be tested is mounted on the guide system to be tested and fixed together with the guide system to a support of the three-dimensional translation stage, and moves with the three-dimensional translation stage.

[0008] The optical system is used to collimate the light beam and split the light source. The light source first passes through the optical system to illuminate the surface of the four-quadrant detector under test. At the same time, the light reflected by the surface of the four-quadrant detector under test is reflected by the optical system and received by the measuring camera.

[0009] The measuring camera is used to obtain the energy distribution image of the light spot and transmit it to the host computer;

[0010] The measured guidance system is used to obtain the output photoelectric conversion signal of the measured four-quadrant detector, calculate and convert it into light spot offset information, and transmit it to the host computer;

[0011] The host computer is used to calculate the light spot energy center offset coordinates based on the energy distribution image of the light spot; and, based on the light spot energy center offset coordinates and the light spot offset information output by the measured guidance system, calculate the calibration coefficient and transmit it back to the measured guidance system.

[0012] Preferably, the three-dimensional translation stage is connected to the host computer via a serial port, and moves under the control of the host computer so that the center of the four-quadrant detector under test is kept at the same height as the optical axis of the optical system.

[0013] Preferably, the optical system includes a semi-transparent and semi-reflective mirror and a collimating module.

[0014] The collimating module is used to collimate the light emitted by the light source into parallel light;

[0015] The semi-transparent and semi-reflective mirror transmits and reflects parallel light in a certain proportion.

[0016] Preferably, the collimating module adopts a collimating lens group.

[0017] Preferably, the semi-transparent and semi-reflective mirrors usually split light in a 5:5 ratio.

[0018] Preferably, the system further comprises an attenuator, and the light beam reflected by the semi-transparent and semi-reflective mirror is received by the measuring camera after passing through the attenuator.

[0019] Preferably, the measuring camera is a CCD detection camera.

[0020] Preferably, the measuring camera and the measured guidance system are both connected to the host computer.

[0021] The specific implementation method of the host computer calculating the calibration coefficient is:

[0022] Obtaining the light spot image measured by the measuring camera and processing it to obtain the offset coordinates of the light spot energy center;

[0023] Obtaining the light spot offset information output by the measured guidance system;

[0024] Changing the position of the light spot irradiated on the four-quadrant photoelectric detector under test, obtaining the light spot energy center offset coordinates measured by multiple groups of measurement cameras and the light spot offset information array output by the measured guidance system;

[0025] A linear fit is performed based on the acquired array to obtain a calibration coefficient, which is then transmitted back to the guidance system under test.

[0026] The present invention also provides a testing method based on the above-mentioned four-quadrant photoelectric detector testing system, comprising:

[0027] According to the test content requirements, the light source is controlled to output light and transmitted to the optical system for beam collimation and splitting. The transmitted light is irradiated onto the surface of the four-quadrant detector under test. The reflected light from the surface of the four-quadrant detector is reflected by a semi-transparent and semi-reflective mirror and then passes through an attenuator to irradiate the surface of the measurement camera.

[0028] During the test calibration process, a light spot is irradiated at a certain point X on the four-quadrant photoelectric detector under test. The light spot image is captured by the measurement camera and transmitted to the host computer. The host computer processes the light spot image and obtains the offset coordinates of the light spot energy center in the image, which are marked as (x, y). The guidance system under test outputs the light spot offset information (Ex, Ey) to the host computer.

[0029] Move the three-dimensional translation stage to illuminate the light spot at point Y on the four-quadrant detector under test. The light spot image is captured by the measuring camera and transmitted to the host computer. The host computer processes the light spot image and obtains the offset coordinates of the light spot energy center in the image, which are marked as (x1, y1). The measured guidance system outputs the light spot offset information (Ex1, Ey1) to the host computer.

[0030] And so on, after multiple moves, we get a series of arrays (x2, y2), (x3, y3), ..., (xn, yn) and (Ex2, Ey2), (Ex3, Ey4), ..., (Exn, Eyn);

[0031] Based on the linear relationship of the obtained array, the fitting calculation of discrete point data is performed to obtain the corresponding calibration coefficient and ;

[0032] The calibration factor and Transmitted back to the guidance system under test.

[0033] Preferably, the method further comprises:

[0034] Before testing, adjust the three-dimensional translation stage according to the position of the test system's optical axis so that the center of the four-quadrant detector under test and the optical axis of the optical system output are at the same height.

[0035] The beneficial effects achieved by the present invention are as follows:

[0036] The present invention provides a four-quadrant photoelectric detector testing system, which realizes the testing and calibration of the calibration coefficient of the four-quadrant detector used in the guidance system, meets the high-efficiency testing requirements, improves the accuracy of the guidance system, and further enhances the application capability of the four-quadrant detector guidance system, and can realize automated testing and calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic structural diagram of a four-quadrant photoelectric detector test system provided by the present invention;

[0038] Figure 2 A schematic diagram of the position of the light spot on the detector during the test and calibration process using the test system of the present invention;

[0039] Figure 3 Schematic diagram of the light spot energy distribution detected by the CCD detector;

[0040] Figure 4 This is a schematic diagram of the x and Ex fitting provided by the present invention. DETAILED DESCRIPTION

[0041] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The embodiments described below with reference to the accompanying drawings are illustrative and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0042] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "end", "bottom", "side", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0043] In the present invention, unless otherwise specified or limited, the terms "connection" and "installation" should be understood broadly. For example, they may refer to fixed connection, direct connection, or connection through an intermediate medium. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0044] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive of other embodiments.

[0045] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0046] The present invention provides a four-quadrant photoelectric detector test system, see Figure 1 , including a light source 9, a three-dimensional translation stage 2, an optical system, a measured guidance system 3, an attenuator 6, a measuring camera 7 and a host computer 1, wherein the measured four-quadrant detector 4 is installed on the measured guidance system 3, and is fixed together with the measured guidance system 3 on the support of the three-dimensional translation stage 2, and moves with the three-dimensional translation stage 2.

[0047] By moving the three-dimensional translation stage, the center of the four-quadrant detector under test is kept at the same height as the optical axis, which facilitates the subsequent adjustment of the light spot to illuminate the surface of the four-quadrant detector under test.

[0048] In the present invention, the three-dimensional translation stage 2 is connected to the host computer 1 via a serial port and moves under the control of the host computer 1 .

[0049] In the present invention, the optical system includes a semi-transparent and semi-reflective mirror 5 and a collimating module 8. The collimating module 8 is used to collimate the light into parallel light to facilitate subsequent processing; the semi-transparent and semi-reflective mirror 5 is used to split the light source. The light source first passes through the semi-transparent and semi-reflective mirror 5 to illuminate the surface of the four-quadrant detector 4 to be measured. At the same time, the light reflected from the surface of the four-quadrant detector 4 to be measured is reflected by the semi-transparent and semi-reflective mirror 5 and received by the measuring camera 7.

[0050] In the present invention, the optical system's light transmission process is as follows: light output from a light source that meets the test requirements is collimated by a collimator module and then transmitted as parallel light to a semi-transparent mirror. The semi-transparent mirror then performs proportional light splitting. The transmitted light then illuminates the surface of the four-quadrant detector under test. Light reflected from the four-quadrant detector is then reflected by the semi-transparent mirror and passed through an attenuator 6 to the surface of a measurement camera 7. The attenuator 6 is used to reduce the energy of the light spot.

[0051] In the present invention, the measuring camera is used to record the energy distribution of the light spot, so as to judge in real time whether the shape of the light spot is deformed, whether the energy is uniform, whether the center of the light spot energy coincides with the center of the light spot shape, etc.

[0052] In the present invention, the measuring camera is also used to determine the position of the light spot on the surface of the four-quadrant detector. There is an isolation groove between the quadrants on the surface of the four-quadrant detector. The surface of the isolation groove is covered with aluminum metal. The reflection of light in this area is significantly stronger than that of the photosensitive surface area. When the light reflected from the surface of the four-quadrant detector is received and imaged by the measuring camera, an obvious cross-shaped bright spot of the light reflected from the isolation groove can be identified in the light spot image. By identifying the cross-shaped bright spot, the position of the center origin of the four-quadrant detector in the camera image can be determined, and the offset of the coordinates of the center position of the light spot from the center of the detector surface can be determined at the same time.

[0053] In the present invention, the guidance system is a key component of the laser terminal guidance system and is the main application scenario of the four-quadrant detector. The guidance system obtains the target's position information by processing the light spot irradiation energy received by the four-quadrant detector. The four-quadrant detector in the present invention is the core component of the guidance system. Its principle is as follows: Figure 2 As shown, the center position of the light spot is ( , ), the four quadrants are represented by A, B, C, and D, and their output voltages are 、 、 、 .

[0054] The current signal output by the four-quadrant detector is summed and subtracted to obtain the offset output signal of the light spot energy center ( 、 ):

[0055] ,

[0056] .

[0057] During actual measurements, it was discovered that the calculated offset of the light spot energy center, obtained after capture and alignment by the guidance system, exhibited positioning errors. This positioning error primarily stems from the non-linear relationship between the offset and the output signal. This error is primarily due to several factors: First, the detection principle itself is affected by the guidance system's deviation from the detected light spot energy center, leading to non-uniformity in the detected light spot energy. Second, issues such as noise and dark current generated by the photodetection and ADC circuits can also lead to inaccurate data.

[0058] Therefore, the spot offset output signal 、 Ideally, the horizontal offset from the energy center of the spot 、 It should be a linear relationship, that is:

[0059] ,

[0060] ,

[0061] In the formula , is the calibration factor.

[0062] In the present invention, the measuring camera 7 and the measured guidance system 3 are both connected to the host computer 1. The host computer 1 is used to receive the spot image measured by the measuring camera 7 and the test signal generated by the measured guidance system 3, and calculate the calibration coefficient.

[0063] In the present invention, the host computer calculates the calibration coefficient in the following specific implementation manner:

[0064] Obtaining the light spot image measured by the measuring camera and processing it to obtain the light spot energy center offset;

[0065] Obtaining the light spot offset output by the guidance system under test;

[0066] Changing the position of the light spot irradiated on the four-quadrant photoelectric detector under test, obtaining the light spot energy center offset measured by multiple groups of measurement cameras and the light spot offset array output by the measured guidance system;

[0067] Perform linear fitting based on the acquired array to obtain the calibration coefficients and , and transmitted back to the guidance system under test.

[0068] As a preferred embodiment, the collimating module adopts a collimating lens group.

[0069] As a preferred embodiment, the semi-transparent and semi-reflective mirror splits the light in a 5:5 ratio.

[0070] As a preferred embodiment, the measurement camera can be a CCD detection camera. The CCD detection camera not only has the characteristics of high sensitivity and low noise, but also the frame transfer CCD has the characteristics of full pixel area photosensitivity, high photosensitivity uniformity, and large signal capacity. This embodiment uses an array-type CCD detection camera with a resolution of 1024×1024 with anti-halo capability, which can accurately record the energy distribution of the light spot. When the light spot energy saturates the CCD detection camera, the saturated light signal will not overflow to the adjacent position, causing a halo phenomenon. When the light spot energy is reduced by an adjustable attenuator, the CCD detection camera array can record the energy distribution of the light spot, thereby judging in real time whether the light spot shape is deformed, whether the energy is uniform, whether the light spot energy center coincides with the light spot shape center, etc.

[0071] Based on this, this test system has the following functions:

[0072] 1. Basic functions: The CCD detection camera array can be used as a standard detector to measure the light intensity of the light spot hitting each quadrant of the four-quadrant detector, and then test the light response of each quadrant of the four-quadrant detector and the response uniformity of each quadrant.

[0073] Second, by identifying the position of the four-quadrant surface isolation groove, the position of the light spot on the four-quadrant detector surface can be determined, the position of the center origin of the four-quadrant detector in the camera image can be determined, and the offset of the coordinates of the center of the light spot energy from the center of the detector surface can be determined.

[0074] 3. It can be used as a basis to adjust the light source of the test system to make the light spot more uniform.

[0075] 4. The position measurement results of the four-quadrant detector can be corrected by energy distribution. For details, see Figure 3 , Figure 3 The left picture shows an uneven light spot hitting an array CCD detection camera, where the darker the color, the greater the energy. The actual light spot energy center can be obtained based on the energy distribution measured in real time by the array CCD detection camera. Figure 3 As shown in the figure on the right, based on this, the deviation between the energy center and the spot center can be calculated to correct the position measurement results of the four-quadrant detector.

[0076] Based on the above test system, the test method of the four-quadrant photoelectric detector is described as follows:

[0077] Before testing, adjust the three-dimensional translation stage according to the position of the test system's optical axis so that the center of the four-quadrant detector under test is at the same height as the optical axis output by the optical system;

[0078] According to the test content requirements, the light source is controlled to output light and transmitted to the collimation module, which collimates the light into parallel light. The parallel light is projected onto the semi-transparent and semi-reflective mirror and split according to a certain ratio. The transmitted light is irradiated onto the surface of the four-quadrant detector under test. The reflected light from the surface of the four-quadrant detector is reflected by the semi-transparent and semi-reflective mirror and then passes through the attenuator to irradiate the surface of the measurement camera.

[0079] At the beginning of the test calibration process, the light spot is irradiated at a certain point X on the four-quadrant photoelectric detector under test. The light spot image is captured by the measuring camera and transmitted to the host computer. The host computer processes the light spot image and obtains the position of the light spot energy center in the image as the initial position (x, y), that is, the light spot energy center offset. The light spot offset signal (Ex, Ey) is output to the host computer through the measured guidance system; specifically, Figure 2 As shown in the left picture;

[0080] Move the three-dimensional translation stage to illuminate the light spot at point Y on the four-quadrant detector under test. The light spot image is captured by the measuring camera and transmitted to the host computer. The host computer processes the light spot image and obtains the position of the light spot energy center in the image as the position after movement (x1, y1). The measured light spot offset signal (Ex1, Ey1) after movement is output through the measured guidance system. Figure 2 As shown in the picture on the right;

[0081] Similarly, after multiple moves, a series of arrays (x2, y2), (x3, y3), ..., (xn, yn) and (Ex2, Ey2), (Ex3, Ey4), ..., (Exn, Eyn) are obtained. Based on the linear relationship of the obtained arrays, the fitting calculation of the discrete point data is performed to obtain the corresponding calibration coefficients and , and the linear correlation of the fitted line can also be calculated; Figure 4 Shown is a schematic diagram of the straight line fitting between x and Ex;

[0082] The calibration factor and The data is transmitted back to the guidance system under test and calculated according to the linear relationship between the center offset x, y of the spot size and Ex, Ey to achieve the calibration function.

[0083] During the entire test process, the host computer and CCD detector are the key to this test system. The host computer uses internal modular programs to set and adjust each device in the system and perform corresponding calculations and calibrations. The CCD detector completes the real-time monitoring and calibration of the entire test and calibration process.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A four-quadrant photoelectric detector test system, characterized in that: include: A light source, a three-dimensional translation stage, an optical system, a guide system to be measured, a measuring camera and a host computer; the four-quadrant detector to be measured is installed on the guide system to be measured, and is fixed together with the guide system to be measured on the support of the three-dimensional translation stage, and moves with the three-dimensional translation stage; The optical system is used to collimate the light beam and split the light source. The light source first passes through the optical system to illuminate the surface of the four-quadrant detector under test. At the same time, the light reflected by the surface of the four-quadrant detector under test is reflected by the optical system and received by the measuring camera. The measuring camera is used to obtain the energy distribution image of the light spot and transmit it to the host computer; The measured guidance system is used to obtain the output photoelectric conversion signal of the measured four-quadrant detector, calculate and convert it into light spot offset information, and transmit it to the host computer; The host computer is used to calculate the light spot energy center offset coordinates based on the energy distribution image of the light spot; and, based on the light spot energy center offset coordinates and the light spot offset information output by the measured guidance system, calculate the calibration coefficient and transmit it back to the measured guidance system.

2. A four-quadrant photoelectric detector test system according to claim 1, characterized in that: The three-dimensional translation stage is connected to the host computer via a serial port and moves under the control of the host computer so that the center of the four-quadrant detector under test is kept at the same height as the optical axis of the optical system.

3. A four-quadrant photoelectric detector test system according to claim 1, characterized in that: The optical system includes a semi-transparent and semi-reflective mirror and a collimating module. The collimating module is used to collimate the light emitted by the light source into parallel light; The semi-transparent and semi-reflective mirror transmits and reflects parallel light in a certain proportion.

4. A four-quadrant photoelectric detector test system according to claim 3, characterized in that: The collimating module adopts a collimating lens group.

5. A four-quadrant photoelectric detector testing system according to claim 3, characterized in that: The semi-transparent and semi-reflective mirrors usually split light in a 5:5 ratio.

6. A four-quadrant photoelectric detector testing system according to claim 3, characterized in that: The system further includes an attenuator, and the light beam reflected by the semi-transparent and semi-reflective mirror is received by the measuring camera after passing through the attenuator.

7. A four-quadrant photoelectric detector testing system according to claim 6, characterized in that: The measuring camera is a CCD detection camera.

8. The four-quadrant photoelectric detector test system according to claim 1, characterized in that: The measuring camera and the measured guidance system are both connected to the host computer. The specific implementation method of the host computer calculating the calibration coefficient is: Obtaining the light spot image measured by the measuring camera and processing it to obtain the offset coordinates of the light spot energy center; Obtaining the light spot offset information output by the measured guidance system; Changing the position of the light spot irradiated on the four-quadrant photoelectric detector under test, obtaining the light spot energy center offset coordinates measured by multiple groups of measurement cameras and the light spot offset information array output by the measured guidance system; A linear fit is performed based on the acquired array to obtain a calibration coefficient, which is then transmitted back to the guidance system under test.

9. The testing method of the four-quadrant photoelectric detector testing system according to any one of claims 6 to 8, characterized in that: include: According to the test content requirements, the light source is controlled to output light and transmitted to the optical system for beam collimation and splitting. The transmitted light is irradiated onto the surface of the four-quadrant detector under test. The reflected light from the surface of the four-quadrant detector is reflected by a semi-transparent and semi-reflective mirror and then passes through an attenuator to irradiate the surface of the measurement camera. During the test calibration process, a light spot is irradiated at a certain point X on the four-quadrant photoelectric detector under test. The light spot image is captured by the measurement camera and transmitted to the host computer. The host computer processes the light spot image and obtains the offset coordinates of the light spot energy center in the image, which are marked as (x, y). The guidance system under test outputs the light spot offset information (Ex, Ey) to the host computer. Move the three-dimensional translation stage to illuminate the light spot at point Y on the four-quadrant detector under test. The light spot image is captured by the measuring camera and transmitted to the host computer. The host computer processes the light spot image and obtains the offset coordinates of the light spot energy center in the image, which are marked as (x1, y1). The measured guidance system outputs the light spot offset information (Ex1, Ey1) to the host computer. And so on, after multiple moves, we get a series of arrays (x2, y2), (x3, y3), ..., (xn, yn) and (Ex2, Ey2), (Ex3, Ey4), ..., (Exn, Eyn); Based on the linear relationship of the obtained array, the fitting calculation of discrete point data is performed to obtain the corresponding calibration coefficient and ; The calibration factor and Transmitted back to the guidance system under test.

10. The testing method according to claim 9, characterized in that: The method further comprises: Before testing, adjust the three-dimensional translation stage according to the position of the optical axis of the test system so that the center of the four-quadrant detector under test and the optical axis output of the optical system are kept at the same height.

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