A method for correcting PSD nonlinearity

Abstract

The invention discloses a method for correcting the nonlinearity of PSD, comprising the following steps: building an experimental platform; adjusting an experimental instrument; acquiring experimental data; processing the experimental data to obtain the coordinates of a corrected point. The invention is applicable to the field of photoelectric detection technology, and a five-dimensional bracket can be used to simulate the laser incident on any position of a photosensitive surface at any pitch angle and yaw angle, which depends on the adjustment angle, and has strong practicality; at the same time, an improved table lookup method is used to limit the output position of the PSD within a certain range, and then the parameterized representation of a triangle is used to uniquely determine its position, thereby greatly reducing the amount of calculation; and the requirements on hardware equipment are not high and the convergence speed is fast.

Description

Technical Field

[0001] The invention belongs to the field of photoelectric detection technology, and in particular is a method for correcting PSD nonlinearity. Background Art

[0002] Photoelectric position sensitive detectors (PSD) are semiconductor position sensitive detectors whose output signal is only related to the energy center position of the light spot. They can continuously measure the position of the light spot and have the advantages of high sensitivity, high resolution, fast response speed and simple circuit. They are widely used in photoelectric detection and other fields. However, due to the uneven resistivity of the PSD photosensitive surface and edge effects, the PSD has nonlinear characteristics, which leads to a decrease in the confidence of the data measured by the entire device. Although the linearity of some improved PSDs has been improved, its nonlinearity is still inevitable.

[0003] At present, domestic and foreign scholars mainly use hardware compensation or software methods to correct the nonlinearity of PSD to improve measurement accuracy. Hardware compensation nonlinear correction mainly adds a correction link to the signal processing part. This method is difficult to implement and not universal. Based on the shortcomings of hardware methods, the use of software to implement nonlinear calibration is favored by many scholars. Among them, the linear interpolation method requires the calibration equipment to have higher accuracy. Due to the defects of the interpolation method itself, the edge part is not corrected. The neural network has the problems of slow convergence speed and low correction accuracy. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for correcting the nonlinearity of PSD.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for correcting PSD nonlinearity comprises the following steps:

[0007] Build an experimental platform;

[0008] Adjust experimental equipment;

[0009] Obtain experimental data;

[0010] The experimental data are processed to obtain the coordinates of the corrected points.

[0011] Preferably, the experimental platform includes: a PSD, a lens, a laser and a five-dimensional support, wherein the laser is fixed on the top surface of the five-dimensional support, and the laser alignment is adjusted.

[0012] Preferably, the adjustment experimental instrument comprises:

[0013] Roughly align the laser with the geometric center of the PSD, turn on the laser so that the PSD collects the response of the laser beam emitted by the laser, and adjust the five-dimensional bracket by observing the position output value of the PSD so that the laser beam is aligned with the center of the PSD.

[0014] Preferably, the obtaining of experimental data includes:

[0015] According to the experimental requirements, the five-dimensional bracket is adjusted to change the position of the laser hitting the photosensitive surface of the PSD, and a series of spot sets are obtained for the nonlinear correction of the PSD.

[0016] Preferably, the experimental data processing to obtain the coordinates of the corrected points comprises the following steps:

[0017] The discrete spot coordinates obtained from the PSD calibration experiment are used to divide the entire nonlinear region into several small quadrilaterals, and the photosensitive surface of the PSD is divided into several small squares. The small quadrilaterals correspond to the small squares one by one.

[0018] When the PSD output coordinates are located inside a small quadrilateral corresponding to the nonlinear region, the corresponding small quadrilateral is found based on the fact that the sum of the areas of the four triangles formed by the coordinates and the lines connecting two adjacent vertices of the quadrilateral is equal to the sum of the areas of the quadrilateral.

[0019] Connect the diagonals of the small quadrilateral found to divide it into two small triangles. The sum of the areas of the three triangles formed by the point and the lines connecting the two adjacent vertices of the triangle is equal to the area of ​​the triangle itself to determine which triangle the point is inside.

[0020] The point is parameterized by the three vertices of a triangle, and the corresponding parameter relationship is mapped to the small square corresponding to the PSD photosensitive surface to obtain the corrected coordinate value.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] The present invention utilizes a five-dimensional bracket to simulate the laser incident on any position of the photosensitive surface at any pitch angle and yaw angle, which depends on the adjustment angle and has strong practicality;

[0023] The present invention adopts an improved table lookup method to limit the output position of the PSD within a certain range, and then uses the parameterized representation of the triangle to uniquely determine its position, which greatly reduces the amount of calculation;

[0024] The present invention has low requirements on hardware equipment and has a fast convergence speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a system block diagram of the present invention;

[0026] Figure 2 It is the measurement curve diagram of PSD in the present invention;

[0027] Figure 3 It is a schematic diagram of the point of the present invention being inside a quadrilateral;

[0028] Figure 4 It is a schematic diagram of dividing a quadrilateral into four small triangles and two small triangles according to the present invention. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-4 , further illustrating a specific implementation of a method for correcting PSD nonlinearity of the present invention. A method for correcting PSD nonlinearity of the present invention is not limited to the description of the following embodiments.

[0030] Embodiment 1:

[0031] This embodiment provides a specific structure of a method for correcting PSD nonlinearity, such as Figure 1-4 As shown, the following steps are included:

[0032] Build an experimental platform;

[0033] Adjust experimental equipment;

[0034] Obtain experimental data;

[0035] The experimental data are processed to obtain the coordinates of the corrected points.

[0036] Specifically, the experimental platform includes: PSD, lens, laser and five-dimensional bracket, wherein the laser is fixed on the top surface of the five-dimensional bracket to adjust the laser alignment.

[0037] Specifically, adjust the experimental equipment, including:

[0038] Roughly align the laser with the geometric center of the PSD, turn on the laser so that the PSD collects the response of the laser beam emitted by the laser, and adjust the five-dimensional bracket by observing the position output value of the PSD so that the laser beam is aligned with the center of the PSD.

[0039] Furthermore, experimental data is obtained, including:

[0040] According to the experimental requirements, the five-dimensional bracket is adjusted to change the position of the laser hitting the photosensitive surface of the PSD, and a series of spot sets are obtained for the nonlinear correction of the PSD.

[0041] Further, the experimental data is processed to obtain the coordinates of the corrected points, including the following steps:

[0042] The discrete spot coordinates obtained from the PSD calibration experiment are used to divide the entire nonlinear region into several small quadrilaterals, and the photosensitive surface of the PSD is divided into several small squares. The small quadrilaterals correspond to the small squares one by one.

[0043] When the PSD output coordinates are located inside a small quadrilateral corresponding to the nonlinear region, the corresponding small quadrilateral is found based on the fact that the sum of the areas of the four triangles formed by the coordinates and the lines connecting two adjacent vertices of the quadrilateral is equal to the sum of the areas of the quadrilateral.

[0044] Connect the diagonals of the small quadrilateral found to divide it into two small triangles. The sum of the areas of the three triangles formed by the point and the lines connecting the two adjacent vertices of the triangle is equal to the area of ​​the triangle itself to determine which triangle the point is inside.

[0045] The point is parameterized by the three vertices of a triangle, and the corresponding parameter relationship is mapped to the small square corresponding to the PSD photosensitive surface to obtain the corrected coordinate value.

[0046] Embodiment 2:

[0047] This embodiment provides an implementation method of a method for correcting PSD nonlinearity:

[0048] like Figure 1 As shown, a method for correcting PSD nonlinearity includes the following steps:

[0049] S1 uses the discrete spot coordinates obtained from the calibration experiment to divide the entire nonlinear area into several small quadrilaterals, and divides the photosensitive surface of PSD into several small squares in the same way. The small quadrilaterals and small squares correspond one to one, such as Figure 2 shown.

[0050] S2 assumes that the PSD output coordinates are P(x m ,y m ), then point P must be located inside a small quadrilateral, and the corresponding corrected spot position coordinates are P1(x a ,y a ),like Figure 3 As shown in Figure 2, the purpose of correction is to convert point P inside the small quadrilateral into P1 in the small square. m1 ,y m1 ), B(x m2 ,y m2 ), C(x m3 ,y m3 ), D(x m4 ,y m4 ) are connected to the small quadrilateral formed by connecting PA, PB, PC, and PD respectively. The sum of the areas of the four small triangles is equal to the area of ​​the quadrilateral, such as Figure 4 As shown,

[0051] S ΔPAB +S ΔPBC +S ΔPCD +S ΔPDA =S 四边形ABCD

[0052] By traversing, we can find the small quadrilateral ABCD corresponding to point P. Since the movement of the light spot is continuous, after finding the first light spot, the position of the second light spot can be searched near the first position, narrowing the search range and improving the correction efficiency.

[0053] Divide the small quadrilateral into two triangles, and then use the parameterization of any point in the triangle to calculate the position of point P inside the triangle. Use the coordinates of the three vertices of the triangle to linearly represent the coordinates of point P, such as Figure 4 ,Right now

[0054] P=p 1 ×A+p 2 ×B+p 3 ×D

[0055] Substitute the coordinates to calculate:

[0056]

[0057] Among them, p1, p2, and p3 are three coefficients, and their sizes are:

[0058]

[0059] Calculate the p values ​​of point P in triangle ABD and triangle CBD respectively. If point P is inside the triangle, then

[0060]

[0061] like Figure 4 As shown, point P is inside triangle ABD

[0062] At this time, the coordinates of point P1 in the small square corresponding to point P are:

[0063]

[0064] Therefore, the coordinates of point P1 after correction are:

[0065] (p 1 × a1 +p 2 × a2 +p 3 × a3 ,p 1 ×y a1 +p2 ×y a2 +p 3 ×y a3 ).

[0066] Working principle: Figure 1-4 As shown, firstly, the present invention can simulate the laser incident on any position of the photosensitive surface at any pitch angle and yaw angle by using the five-dimensional bracket, which depends on the adjustment angle and has strong practicality;

[0067] Secondly, the present invention adopts an improved table lookup method to limit the output position of the PSD within a certain range, and then uses the parameterized representation of the triangle to uniquely determine its position, which greatly reduces the amount of calculation;

[0068] Finally, the present invention has low requirements on hardware devices and has a fast convergence speed.

[0069] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method to correct PSD nonlinearity, It is characterized in that The following steps are involved: Build an experimental platform; Adjust experimental equipment; Obtain experimental data; Process the experimental data to obtain the coordinates of the corrected points; The experimental data processing to obtain the coordinates of the corrected points includes the following steps: The discrete spot coordinates obtained from the PSD calibration experiment are used to divide the entire nonlinear region into several small quadrilaterals, and the photosensitive surface of the PSD is divided into several small squares. The small quadrilaterals correspond to the small squares one by one. When the PSD output coordinates are located inside a small quadrilateral corresponding to the nonlinear region, the corresponding small quadrilateral is found based on the fact that the sum of the areas of the four triangles formed by the coordinates and the lines connecting two adjacent vertices of the quadrilateral is equal to the sum of the areas of the quadrilateral. Connect the diagonals of the small quadrilateral found to divide it into two small triangles. The sum of the areas of the three triangles formed by the point and the lines connecting the two adjacent vertices of the triangle is equal to the area of ​​the triangle itself to determine which triangle the point is inside. The point is parameterized by the three vertices of a triangle, and the corresponding parameter relationship is mapped to the small square corresponding to the PSD photosensitive surface to obtain the corrected coordinate value.

2. A method for correcting PSD nonlinearity as claimed in claim 1, It is characterized in that The experimental platform includes: PSD, lens, laser and five-dimensional support, wherein the laser is fixed on the top surface of the five-dimensional support, and the laser alignment is adjusted.

3. A method for correcting PSD nonlinearity as claimed in claim 1, It is characterized in that The adjustment experiment instrument comprises: Roughly align the laser with the geometric center of the PSD, turn on the laser so that the PSD collects the response of the laser beam emitted by the laser, and adjust the five-dimensional bracket by observing the position output value of the PSD so that the laser beam is aligned with the center of the PSD.

4. A method for correcting PSD nonlinearity as claimed in claim 1, It is characterized in that The obtaining of experimental data comprises: According to the experimental requirements, the five-dimensional bracket is adjusted to change the position of the laser hitting the photosensitive surface of the PSD, and a series of spot sets are obtained for the nonlinear correction of the PSD.

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