A correction method for light intensity uniformity

Abstract

The present invention discloses a method for correcting light intensity uniformity. An illuminometer automatically moves to measure the light intensity of the projection surface of a 3D molding system. The number of measurement points on the projection surface can be set according to actual conditions; the more measurement points, the higher the uniformity. Adjustments are first made based on the light intensity of the measurement points. Measurement points with high light intensity are lowered to within a set range through masking or current adjustment. The grayscale value of each measurement point is then obtained by consulting a transmittance table or performing calculations. The remaining portions of the projection surface are then obtained through bilinear interpolation based on the grayscale values ​​of the measurement points. The resulting projection surface exhibits high light intensity uniformity.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a method for correcting light intensity uniformity. Background Art

[0002] In 3D printing systems based on projection surfaces, the light intensity distribution on the projection surface is typically uneven, which can affect printing accuracy if directly printed. Therefore, the light intensity needs to be corrected for uniformity before printing. Currently, there are two methods. One is to manually measure with a illuminance meter, manually input the measured values ​​into a computer, and then perform corrections using software. This method has the advantages of high accuracy, ease of operation, and low cost. However, the number of measurement points should be limited, otherwise the large amount of data input will affect efficiency. If the number of measurement points is too small, the uniformity will be poor. Another method is to use a camera to capture the image. However, such cameras are generally expensive and, due to the camera's imaging principle, they cannot fully reflect the uniformity of the light intensity distribution. The advantage of this solution is that it is easy to use and does not require manual input. The disadvantage is that it is inconvenient to re-calibrate after leaving the factory. Summary of the Invention

[0003] The object of the present invention is to provide a method for correcting light intensity uniformity, wherein the illuminometer automatically moves a large number of measuring points, has high uniformity and low cost.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for correcting light intensity uniformity comprises the following steps:

[0006] (1) Place the 3D molding system in a measuring device, which is equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D molding system and measures the light intensity of the projection surface.

[0007] (2) Set the number of measurement points m×n and calculate the center position of the measurement points;

[0008] (3) The optical machine of the 3D molding system projects the measurement block image onto the projection surface in sequence. Each time the projection is made, the illuminance meter probe is moved to the center of the measurement point, and the illuminance meter data is read and recorded.

[0009] (4) Based on the light intensity data of all measurement points, determine whether the measurement point needs to adjust the light intensity. Move the illuminometer to the position of the first measurement point that needs to adjust the light intensity. The optical machine projects the measurement block image to the measurement point, adjusts its grayscale value until its light intensity is within the set range, records its grayscale value and calculates the grayscale adjustment rate to achieve the light intensity adjustment of the measurement point.

[0010] (5) The grayscale values ​​of the remaining measurement points to be adjusted are calculated according to the grayscale adjustment rate. After adjusting to the grayscale value, the adjusted light intensity is measured by the illuminance meter to determine whether the adjusted light intensity is within the set range. If the adjusted light intensity is still not within the set range, the grayscale value is fine-tuned and the light intensity is re-measured until the light intensity is within the set range. The grayscale value of each point is recorded, and the above steps are repeated until the light intensity adjustment of all measurement points to be adjusted is completed;

[0011] (6) After obtaining the grayscale values ​​of all measurement points, the grayscale values ​​of the rest of the projection surface are obtained by bilinear interpolation based on the measurement points, and the grayscale mask of the entire projection surface is obtained. The grayscale mask is set on the projection surface to calibrate the light intensity uniformity of the projection surface.

[0012] Because the measurement device automatically controls the position of the illuminometer, the number of measurement points on the projection surface can be set based on actual conditions; the more measurement points, the higher the uniformity. First, the grayscale value of the measurement block is adjusted based on the light intensity at the measurement point. The grayscale value of any measurement point with high light intensity is lowered to within the set range by adjusting the grayscale value. This process is repeated, and the grayscale value of each measurement point on the mask is recorded. The remaining portion of the projection surface is then bilinearly interpolated based on the grayscale values ​​of the measurement points, resulting in a highly uniform projection surface.

[0013] Furthermore, in step (2), the position of the measuring point is calculated as follows: Assume that the length and width of the projection surface are Sx and Sy respectively, and the length and width of the illuminance meter probe are L and w respectively, then the position of the measuring point is Px i =R / 2+i×(Sx-R) / m; Py j =w / 2+j×(Sy-w) / n.

[0014] Furthermore, in step (3), the grayscale of the measurement block image is 255, and the size of the measurement block image is (R+2)×(w+2). The grayscale of the measurement block image is initially set to white so that the entire projection surface reaches the highest light intensity.

[0015] Furthermore, in step (4), the specific method of determining whether the light intensity of the measuring point needs to be adjusted is as follows: the light intensity data of all the measuring points are statistically analyzed to obtain the minimum light intensity L of the measuring point. min and measure the maximum light intensity L max , compare the set minimum light intensity L0 and the measured minimum light intensity L min , if L min >L0, then the minimum light intensity L=L min , otherwise the minimum light intensity L=L0; if the light intensity at the measuring point is ≤L, there is no need to adjust the light intensity at the measuring point; otherwise, a mask needs to be added to adjust the light intensity at the measuring point. According to the set uniformity requirement P, the light intensity adjustment range det=(1-P)*L is obtained.

[0016] 3D printing systems usually have a set minimum light intensity L0 according to their own printing requirements. A value lower than this may affect the printing effect. Therefore, it is necessary to measure the minimum light intensity L min For comparison, choose the lowest light intensity L.

[0017] Furthermore, in step (4), the specific method of adjusting the light intensity is as follows: the measuring device moves the illuminometer probe to the first measuring point position that needs to be adjusted, and the optical machine projects the measuring block image, and sets its grayscale to g = 255-(L i -L)×u,u=30 / (L max -L min ), where L i is the current light intensity, u is the grayscale adjustment rate, 30 is the empirical value of grayscale adjustment, and the adjusted light intensity L is measured. i ’ , if |L i ’- L i |≤det, record the gray value of this point and complete the light intensity adjustment of this measurement point, otherwise according to L i ’ Greater or less than L i Fine-tune the grayscale by reducing or increasing it by 1, and re-measure and judge until |L i ’- L i |≤det, complete the light intensity adjustment of this measurement point, and finally update u=(255-g) / (L max -L min ).

[0018] The grayscale value of the first measurement point requiring light intensity adjustment is fine-tuned according to the above method, and its light intensity is reduced until it falls within the set range, thereby obtaining a more accurate grayscale adjustment rate u.

[0019] Furthermore, the specific method of step (5) is as follows: after obtaining the updated grayscale adjustment rate u, set the grayscale value of the remaining measurement points that need to adjust the light intensity to g = 255-(Li-L)*u, and then measure the adjusted light intensity L i ’ , if |L i ’- L i |≤det, record the gray value of this point and complete the light intensity adjustment of this measurement point, otherwise according to L i ’ Greater or less than L i Fine-tune the grayscale by reducing or increasing it by 1, and re-measure and judge until |L i ’- L i|≤det, complete the adjustment of the light intensity at the remaining measurement points, and record the final gray values of each point.

[0020] Since the updated gray-scale adjustment rate u in step (4) is already relatively accurate, the mask gray values of other measurement points that need to adjust the light intensity can be calculated according to the obtained gray-scale adjustment rate u. Generally, no fine-tuning is required or only fine-tuning is needed once.

[0021] Furthermore, in step (6), the gray values of other points inside the mask image are obtained by bilinear interpolation. The specific method is as follows: If the point q(x, y) is inside the measurement block, the four measurement points of the measurement block closest to the point q(x, y) are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively. The gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of the point q is obtained through the following formula:

[0022]

[0023] Furthermore, in step (6), the gray values of the points on the edge of the mask image are obtained by bilinear extrapolation. If the point p(x, y) is outside the measurement block, the four measurement points of the measurement block closest to the point p(x, y) are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively. The gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of the point q is obtained through the following formula:

[0024]

[0025] Furthermore, the value g of the p point obtained by linear extrapolation needs to be compared with the value gr of the nearest interpolation fitting point. If g < gr, then g = gr. The bilinear interpolation method in step (6) will calculate the values of all points inside the rectangle formed by the four points. The value of the gr point can be obtained by drawing a perpendicular line from the p point to the nearest side of the rectangle.

[0026] Furthermore, in step (6), the gray values of the points on the edge of the mask image are obtained by the method of edge repetition.

[0027] A method for correcting light intensity uniformity includes the following steps:

[0028] (a) Place the 3D forming system in the measuring device. The measuring device is equipped with an illuminometer that can move along the XYZ axes. The illuminometer is aligned with the projection surface of the 3D forming system and measures the light intensity of the projection surface;

[0029] (b) Set the number of measurement points m×n, and calculate the central positions of the measurement points;

[0030] (c) The optical machine of the 3D modeling system projects the measurement block image onto the projection surface in sequence. Each time it projects, it moves the illuminance meter probe to the center of the measurement point, reads the illuminance meter data, and records it.

[0031] (d) Calculate the corresponding transmittance using the ratio of the light intensity Li at all measurement points to the set light intensity L. Look up the pre-measured grayscale value-transmittance table for the same model to obtain the grayscale value corresponding to each measurement point.

[0032] (e) After obtaining the grayscale values ​​of all measurement points, the grayscale values ​​of the rest of the projection surface are obtained by bilinear interpolation based on the measurement points to obtain a grayscale mask image of the entire projection surface. This grayscale mask image is set on the projection surface to calibrate the light intensity uniformity of the projection surface.

[0033] Furthermore, step (c) further includes, after reading and recording the illuminometer data, traversing the above-mentioned sampling points to obtain the sampling point position of the lowest light intensity point; if the light intensity at the lowest point is less than the set light intensity L, increasing the UV-LED current of the 3D molding system to increase the light intensity so that the light intensity is between [L, 105% * L]; if the light intensity at the point is greater than L * 105%, reducing the UV-LED current of the 3D molding system to reduce the light intensity so that the light intensity is between [L, 105% * L];

[0034] If the current is adjusted, the entire projection surface will be re-sampled with an illuminance meter to collect the adjusted light intensity; if the current is not adjusted, the light intensity will not be collected again.

[0035] Furthermore, the pre-measured grayscale value-transmittance table for the same model is obtained by placing the 3D molding system of that model into a measuring device equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D molding system, and the grayscale value of the projection surface is set to 255. The illuminometer measures the light intensity I. The grayscale value of the projection surface is adjusted from 255 to 0, and the light intensity Mi at each grayscale value is measured and recorded. According to the formula "transmittance = light intensity Mi / light intensity I * 100%, the transmittance at different grayscale values ​​is calculated and a transmittance table is generated. The above transmittance table is related to the projection system within the 3D molding system, and the same system only needs to be measured once.

[0036] Furthermore, in step (b), the position of the measuring point is calculated as follows: Assume that the length and width of the projection surface are Sx and Sy respectively, and the length and width of the illuminance meter probe are R and w respectively, then the position of the measuring point is Px i =R / 2+i×(Sx-R) / m; Py j =w / 2+j×(Sy-w) / n.

[0037] Furthermore, in step (c), the grayscale of the measurement block image is 255, and the size of the measurement block image is (R+2)×(w+2);

[0038] Further, for the gray values of other points inside the mask image, they are obtained by bilinear interpolation. The specific method is as follows: If the point q(x, y) is inside the measurement block, the four measurement points of the measurement block closest to the point q(x, y) are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively. The gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of the point q is obtained through the following formula:

[0039]

[0040] Further, in step (e), for the gray values of the points on the edge of the mask image, they are obtained by bilinear extrapolation. If the point p(x, y) is outside the measurement block, the four measurement points of the measurement block closest to the point p(x, y) are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively. The gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of the point q is obtained through the following formula:

[0041]

[0042] Further, the value g of the p point obtained by linear extrapolation needs to be compared with the value gr of the nearest interpolation fitting point. If g < gr, then g = gr. The bilinear interpolation method in step (e) will calculate the values of all points inside the rectangle formed by the four points. By drawing a perpendicular line from the p point to the nearest side of the rectangle, the value of the gr point can be obtained.

[0043] Due to adopting the above technical solution, the present invention has the following beneficial effects:

[0044] 1. In the generation stage, it can automatically test m×n points. The number of points is large. Through the communication protocol, it uploads to the computer or controls the computer through the printer, without the need for manual recording of input data, and the processing speed is fast.

[0045] 2. It also provides a tool that can individually adjust the gray compensation value for each measurement point position, which is very convenient for local adjustment of the uniformity after using for a period of time.

[0046] 3. The method of using the transmittance table is very convenient and fast. The transmittance table is related to the projection system inside the 3D forming system. For the same type of system, it only needs to be measured once.

[0047] 4. There is no need to use a camera, saving costs.

[0048] 5. After debugging, the light intensity uniformity of the projection surface is good. Description of the Drawings

[0049] The present invention will be further described below with reference to the accompanying drawings.

[0050] Figure 1 Schematic diagram of the structure of the 3D molding system after the measuring device is placed in it.

[0051] Figure 2 Schematic diagram of point q inside the grayscale mask image.

[0052] Figure 3 Schematic diagram of point q outside the grayscale mask image. DETAILED DESCRIPTION

[0053] Example 1

[0054] like Figure 1 As shown, the measuring device includes a support frame 1, an XYZ axis control component 2 and an illuminometer 3. The 3D molding system 4 is placed in the support frame. The illuminometer can move in the X-axis, Y-axis and Z-axis directions under the control of the XYZ axis control component.

[0055] A method for correcting light intensity uniformity comprises the following steps:

[0056] (1) The optical system of the 3D molding system is placed in the support frame of the measuring device. The measuring device is equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D molding system and measures the light intensity of the projection surface.

[0057] (2) Set the number of measurement points to m×n and calculate the center position of the measurement point. Assume that the length and width of the projection surface are Sx and Sy, and the length and width of the illuminance meter probe are R and w, respectively. Then the position of the measurement point is Pxi = R / 2 + i×(Sx-R) / m; Pyj = w / 2 + j×(Sy-w) / n. For example, if n = 5, m = 12, R = 24; w = 32.4; Sx = 288; Sy = 162, the first column of sampling points is obtained: [(12, 16.2)(12, 48.6)(12, 81)(12, 113.4)(12, 145.8)].

[0058] (3) The optical machine of the 3D modeling system sequentially projects a measurement block image with a grayscale of 255 and a size of (R+2)×(w+2) or larger onto the projection surface. Each time a projection is made, the illuminance meter probe is moved to the center of the measurement point, and the system waits for 5 seconds. The illuminance meter data is read and recorded via the communication protocol. When the probe is placed, the center of the illuminance meter probe coincides with the center of the measurement block.

[0059] (4)a. Statistically analyze the light intensity data of all measurement points to obtain the lowest light intensity L at the measurement point. min and measure the maximum light intensity L max , compare the set minimum light intensity L0 and the measured minimum light intensity L min, if L min >L0, then the minimum light intensity L=L min , otherwise the minimum light intensity L=L0; if the light intensity at the measuring point is ≤ the minimum light intensity L, there is no need to adjust the light intensity at the measuring point. Otherwise, a mask needs to be added to adjust the light intensity at the measuring point. According to the set uniformity requirement P (generally P≥95%), the light intensity adjustment range det=(1-P)*L is obtained.

[0060] b. The measuring device moves the illuminometer probe to the first measuring point where the light intensity needs to be adjusted, and the optical machine projects the measurement block image, setting its grayscale to g = 255-(L i -L)×u,u=30 / (L max -L min ), where L i is the current light intensity, u is the grayscale adjustment rate, 30 is the empirical value of grayscale adjustment, and the adjusted light intensity L is measured. i ’ , if |L i ’- L i |≤det, record the gray value of this point and complete the mask adjustment of this measurement point, otherwise according to L i ’ Greater or less than L i Fine-tune the grayscale by reducing or increasing it by 1, and re-measure and judge until |L i ’- L i |≤det, complete the mask adjustment of this measurement point, and finally update the grayscale adjustment rate u=(255-g) / (L max -L min ).

[0061] (5) According to the updated grayscale adjustment rate u, set the grayscale value of the remaining measurement points that need to adjust the light intensity to g = 255-(Li-L)*u, and then repeat the process operation of step (4) to measure the adjusted light intensity L i ’ , if |L i ’- L i |≤det, record the gray value of this point and complete the light intensity adjustment of this measurement point, otherwise according to L i ’ Greater or less than L i Fine-tune the grayscale by reducing or increasing it by 1, and re-measure and judge until |L i ’- L i|≤det, complete the adjustment of the light intensity at the remaining measurement points, and record the final gray values of each point. Since the updated gray adjustment rate u in step (4) is already relatively accurate, the gray values of other measurement points that need to adjust the light intensity can be calculated according to the obtained gray adjustment rate u. Generally, no fine-tuning is required or only fine-tuning is needed once.

[0062] (6) After obtaining the gray values of all measurement points, the gray values of other points inside the mask image are obtained by bilinear interpolation to obtain the gray mask image of the entire projection plane. Set this gray mask image on the projection plane to calibrate the light intensity uniformity of the projection plane.

[0063] As Figure 2 shown, if the point q(x, y) is located inside the measurement block, the four measurement points of the measurement block are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively, and the gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of point q is obtained through the following formula:

[0064]

[0065] For the gray values of the points on the edge of the mask image, they are obtained by bilinear extrapolation. As Figure 3 shown, if the point p(x, y) is located outside the measurement block, the four measurement points of the measurement block closest to the point p(x, y) are p0(x1, y1), p1(x2, y1), p2(x1, y2), p3(x2, y2) respectively, and the gray values of these four measurement points are g0, g1, g2, g3 respectively. The gray value of point q is obtained through the following formula:

[0066]

[0067] The value g of point p obtained by linear extrapolation needs to be compared with the value gr of the nearest interpolation fitting point. If g < gr, then g = gr.

[0068] In step (6), for the gray values of the points on the edge of the mask image, they can also be obtained by edge repetition (that is, copying the data of the row or column where the outermost circle of measurement points is located).

[0069] Embodiment 2

[0070] The measuring device is the same as that in Embodiment 1. A method for correcting light intensity uniformity includes the following steps:

[0071] To obtain a grayscale-transmittance table for a specific 3D molding system model: Place the 3D molding system model in a measuring device equipped with an illuminometer that can be moved along the X, Y, and Z axes. Aim the illuminometer at the projection surface of the 3D molding system. Set the projection surface grayscale value to 255 and measure the light intensity I, for example, 6000. Adjust the projection surface grayscale value from 255 to 0, measuring and recording the light intensity Mi at each grayscale value, for example, [6000, ..., 2000, ..., 0]. Using the formula "transmittance = light intensity Mi / light intensity I * 100%, calculate the transmittance at different grayscale values ​​and create a transmittance table, for example, [(100%, 255), ...(33.33%, 135), ...(0%, 0)]. For greater accuracy, measure multiple machines of the same model and take the average value.

[0072] (a) Place the optical system of a 3D-molding system of the same model to be tested into the support frame of a measuring device. The measuring device is equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D-molding system and measures the light intensity on the projection surface.

[0073] (b) Set the number of measurement points to m × n and calculate the center positions of the measurement points. Assume the length and width of the projection surface are Sx and Sy, respectively, and the length and width of the illuminance meter probe are R and w, respectively. Then the positions of the measurement points are Pxi = R / 2 + i × (Sx - R) / m; Pyj = w / 2 + j × (Sy - w) / n. For example, if n = 5, m = 12, R = 24; w = 32.4; Sx = 288; Sy = 162, the first column of sampling points is [(12, 16.2)(12, 48.6)(12, 81)(12, 113.4)(12, 145.8)].

[0074] (c) The 3D modeling system's optical machine sequentially projects a measurement block image with a grayscale of 255 and an area of ​​(R+2)×(w+2) or larger onto the projection surface. Each time a measurement block is projected, the illuminance meter probe is moved to the center of the measurement point, and after a 5-second wait, the illuminance meter data is read and recorded via the communication protocol. The probe is positioned so that the center of the illuminance meter probe coincides with the center of the measurement block.

[0075] Traverse the above sampling points and obtain the sampling point position of the lowest light intensity. If the light intensity at the lowest point is less than the set light intensity L, increase the UV-LED current of the 3D molding system to increase the light intensity so that the light intensity is between [L, 105% * L]. If the light intensity at this point is greater than L * 105%, reduce the UV-LED current of the 3D molding system to reduce the light intensity so that the light intensity is between [L, 105% * L]. Adjustment strategy: If the actual light intensity is greater than 105% * L, reduce the current by 1%; if the light intensity is less than L, increase the current by 1%. Repeat the above strategy until the light intensity at the lowest point meets the conditions.

[0076] If the current is adjusted, the entire projection surface will be re-sampled with an illuminance meter to collect the adjusted light intensity; if the current is not adjusted, the light intensity will not be collected again.

[0077] (d) Calculate the corresponding transmittance using the ratio of the light intensity Li at all measurement points to the set light intensity L. Consult the previously measured grayscale value-transmittance table for the same model to obtain the corresponding grayscale value for each measurement point. For example, if the light intensity Li at the measurement point is 6234 and the set light intensity is L = 6000, calculate the transmittance at that point as S = L / Li * 100 = 96.25%. Consult the transmittance table and select the grayscale value closest to S, for example, 245.

[0078] (e) After obtaining the grayscale values ​​of all measurement points, the grayscale values ​​of the remaining portions of the projection surface are obtained using bilinear interpolation with the measurement points as a reference, thereby obtaining a grayscale mask for the entire projection surface. This grayscale mask is then placed on the projection surface to calibrate the light intensity uniformity of the projection surface. The specific method for step (e) can be the same as in Example 1.

[0079] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are included within the scope of protection of the present invention.

Claims

1. A method for correcting light intensity uniformity, characterized by: The steps include: (1) Place the 3D molding system into a measuring device. The measuring device is equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D molding system and measures the light intensity of the projection surface. (2) Set the number of measurement points m×n and calculate the center position of the measurement point. The position of the measurement point is calculated as follows: Let the length and width of the projection surface be Sx and Sy respectively, and the length and width of the illuminance meter probe be R and w respectively, then the position of the measurement point is Px i =R / 2+i× (Sx-R) / m; Py j = w / 2+j×(Sy-w) / n; In step (3), the grayscale of the measurement block image is 255, and the size of the measurement block image is (R+2)×(w+2); (3) The optical machine of the 3D molding system projects the measurement block image onto the projection surface in sequence. Each time it projects, it moves the illuminance meter probe to the center of the measurement point, reads the illuminance meter data and records it; (4) According to the light intensity data of all measurement points, it is determined whether the light intensity of the measurement point needs to be adjusted. The illuminometer is moved to the position of the first measurement point that needs to adjust the light intensity. The optical machine projects the measurement block image to the measurement point and adjusts its grayscale value until its light intensity is within the set range. The grayscale value is recorded and the grayscale adjustment rate is calculated to achieve the light intensity adjustment of the measurement point. (5) The grayscale values ​​of the remaining measurement points to be adjusted are calculated according to the grayscale adjustment rate. After adjusting to the grayscale value, the adjusted light intensity is measured by the illuminance meter to determine whether the adjusted light intensity is within the set range. If the adjusted light intensity is still not within the set range, the grayscale value is fine-tuned and the light intensity is re-measured until the light intensity is within the set range. The grayscale value of each point is recorded. The above steps are repeated until all the measurement points to be adjusted are masked and the light intensity adjustment is completed; (6) After obtaining the grayscale values ​​of all measurement points, the grayscale values ​​of the rest of the projection surface are obtained by bilinear interpolation based on the measurement points to obtain the grayscale mask image of the entire projection surface. The grayscale mask image is set on the projection surface to calibrate the light intensity uniformity of the projection surface.

2. The method for correcting light intensity uniformity according to claim 1, characterized in that: In step (4), the light intensity data of all measurement points are statistically analyzed to determine whether the light intensity of the measurement point needs to be adjusted. The specific method is as follows: Based on the obtained light intensity data of all measurement points, the minimum light intensity L of the measurement point is obtained. min and measure the maximum light intensity L max , compare the set minimum light intensity L0 and the measured minimum light intensity L min , if L min >L0, then the minimum light intensity L=L min , otherwise the minimum light intensity L=L0; if the light intensity at the measurement point is ≤ the minimum light intensity L, there is no need to adjust the light intensity at the measurement point. Otherwise, a mask needs to be added to adjust the light intensity at the measurement point. According to the set uniformity requirement P, the light intensity adjustment range det = (1-P)*L is obtained; In step (4), the specific method of adjusting the light intensity is as follows: the measuring device moves the illuminometer probe to the first measuring point that needs to be adjusted, and the optical machine projects the measuring block image and sets its grayscale to g = 255 - (L i - L) ×u, u=30 / (L max -L min ), where L i is the current light intensity, u is the grayscale adjustment rate, 30 is the empirical value of grayscale adjustment, and the adjusted light intensity L is measured. i ’ , if |L i ’ - L i |≤det, record the gray value of this point and complete the light intensity adjustment of this measurement point, otherwise according to L i ’ Greater or less than L i Fine-tune the grayscale by reducing or increasing it by 1, and re-measure and judge until |L i ’ - L i |≤det, complete the light intensity adjustment of this measurement point, and finally update u = (255-g) / (L max -L min ).

3. The method for correcting light intensity uniformity according to claim 2, wherein: The specific method of step (5) is as follows: after obtaining the updated grayscale adjustment rate u, set the grayscale value of the measurement block of the remaining measurement points that need to adjust the light intensity with the mask to g = 255 - (Li - L) * u, and then measure the adjusted light intensity Li'. If |Li' -Li| ≤ det, record the grayscale value of this point and complete the light intensity adjustment of this measurement point. Otherwise, fine-tune the grayscale by reducing or increasing 1 according to whether Li' is greater than or less than Li, and re-measure and judge until |Li' -Li| ≤ det. Complete the light intensity adjustment of the remaining measurement points and record the final grayscale value of each point.

4. The method for correcting light intensity uniformity according to claim 1, wherein: The grayscale values ​​of other points inside the mask are obtained by bilinear interpolation. The specific method is: if point q(x,y) is inside the measurement block, the four measurement points of the measurement block closest to point q(x,y) are p0(x1,y1), p1(x2,y1), p2(x1,y2), and p3(x2,y2). The grayscale values ​​of these four measurement points are g0, g1, g2, and g3 respectively. The grayscale value of point q is obtained by the following formula: g = ； In step (6), the grayscale values ​​of the points at the edge of the mask image are obtained by bilinear interpolation. If point p(x,y) is outside the measurement block, the four measurement points of the measurement block closest to point p(x,y) are p0(x1,y1), p1(x2,y1), p2(x1,y2), and p3(x2,y2). The grayscale values ​​of these four measurement points are g0, g1, g2, and g3 respectively. The grayscale value of point q is obtained by the following formula: g = ； The p-point value g obtained by linear extrapolation needs to be compared with the nearest interpolated fitting point value gr. If g < gr, then g = gr.

5. The method for correcting light intensity uniformity according to claim 1, wherein: In step (6), the grayscale values ​​of the points at the edge of the mask image are obtained by edge repetition.

6. A method for correcting light intensity uniformity, characterized by: The steps include: (a) The 3D modeling system is placed in a measuring device equipped with an illuminometer that can move along the X, Y, and Z axes. The illuminometer is aligned with the projection surface of the 3D modeling system and measures the light intensity on the projection surface. (b) Set the number of measurement points m × n and calculate the center position of the measurement points; (c) The optical machine of the 3D molding system sequentially projects the measurement block image onto the projection surface. During each projection, the illuminometer probe is moved to the center of the measurement point, and the illuminometer data is read and recorded. After reading and recording the illuminometer data, the sampling points are traversed to obtain the sampling point position of the lowest light intensity. If the light intensity at the lowest point is less than the set light intensity L, the current of the 3D molding system is increased to increase the light intensity so that the light intensity is between [L, 105% * L]. If the light intensity at this point is greater than L * 105%, the current of the 3D molding system is reduced to reduce the light intensity so that the light intensity is between [L, 105% * L]. If the current is adjusted, the entire projection surface is again illuminated with a illuminance meter to collect the adjusted light intensity; If no current adjustment occurs, the light intensity is not recollected; (d) Calculate the corresponding transmittance using the ratio of the light intensity Li at all measurement points to the set light intensity L. Look up the pre-measured grayscale value-transmittance table for the same model to obtain the grayscale value corresponding to each measurement point. (e) After obtaining the grayscale values ​​of all measurement points, the grayscale values ​​of the rest of the projection surface are obtained by bilinear interpolation based on the measurement points to obtain a grayscale mask image of the entire projection surface. This grayscale mask image is set on the projection surface to calibrate the light intensity uniformity of the projection surface.

7. The method for correcting light intensity uniformity according to claim 6, wherein: The pre-measured grayscale value-transmittance table of the same model is obtained by the following method: placing the 3D molding system of the model into a measuring device, the measuring device is provided with an illuminometer that can move along the XYZ axis, the illuminometer is aligned with the projection surface of the 3D molding system, the grayscale value of the projection surface is set to 255, the illuminometer measures the light intensity I, the grayscale value of the projection surface is adjusted from 255 to 0, the light intensity Mi at each grayscale value is measured and recorded, and according to transmittance = light intensity Mi / light intensity I*100%, the transmittance at different grayscale values ​​is calculated and a transmittance table is formed.

8. The method for correcting light intensity uniformity according to claim 6, wherein: In step (b), the position of the measurement point is calculated as follows: Assume that the length and width of the projection surface are Sx and Sy respectively, and the length and width of the illuminance meter probe are R and w respectively, then the position of the measurement point is Pxi = R / 2 + i × (Sx-R) / m; Pyj = w / 2 + j × (Sy-w) / n; In step (c), the grayscale of the measurement block image is 255, and the size of the measurement block image is (R+2)×(w+2); In step (e), the grayscale values ​​of other points inside the mask image are obtained by bilinear interpolation. The specific method is: if point q(x,y) is inside the measurement block, the four measurement points of the measurement block closest to point q(x,y) are p0(x1,y1), p1(x2,y1), p2(x1,y2), and p3(x2,y2). The grayscale values ​​of these four measurement points are g0, g1, g2, and g3 respectively. The grayscale value of point q is obtained by the following formula: g = ； In step (e), the grayscale values ​​of the points at the edge of the mask are obtained by bilinear interpolation. If point p(x,y) is outside the measurement block, the four measurement points of the measurement block closest to point p(x,y) are p0(x1,y1), p1(x2,y1), p2(x1,y2), and p3(x2,y2). The grayscale values ​​of these four measurement points are g0, g1, g2, and g3 respectively. The grayscale value of point q is obtained by the following formula: g = ； The p-point value g obtained by linear extrapolation needs to be compared with the nearest interpolated fitting point value gr. If g < gr, then g = gr.

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