Micro-LED array measurement method and system based on phase reconstruction

Abstract

The present invention provides a phase-reconstruction-based Micro-LED array measurement method and system, which relates to the field of micro-light-emitting diode display technology. The method includes first obtaining a focal plane image and multiple through-focus plane images of the Micro-LED array to be measured, then using a phase reconstruction model to phase-reconstruct these images to obtain light field information of the light-emitting surface, and then constructing an amplitude-frequency distribution based on the light field information to obtain a light intensity distribution evaluation diagram for different light-emitting angles. Finally, based on the focal plane image and the light intensity distribution evaluation diagram, measurement information including light-emitting angle, luminous intensity ratio, and light intensity uniformity is obtained. The present invention can quickly, accurately, and efficiently detect the light-emitting angle, luminous intensity, and light intensity uniformity of a Micro-LED array, is suitable for large-scale batch testing, improves the accuracy and reliability of measurement, and can be widely applied to the measurement of other light-emitting semiconductor materials.

Description

Technical Field

[0001] The present invention relates to the field of micro light emitting diode (Micro-LED) display technology, and in particular to a Micro-LED array measurement method and system based on phase reconstruction. Background Art

[0002] Micro-LED display technology uses micron-sized light-emitting diodes (LEDs) as light-emitting units. These tiny devices are integrated through advanced semiconductor processes to achieve ultra-high-density displays. However, traditional Micro-LED devices suffer from spatial divergence during light emission, resulting in relatively low luminous efficiency. Furthermore, the large divergence angle can cause light overlap and color crosstalk between adjacent Micro-LED devices, severely impacting display quality.

[0003] To improve the display quality of Micro-LEDs, light collimation and control has become a key step. However, after collimation, accurately measuring the light output angle of the Micro-LEDs becomes particularly important. Furthermore, due to the variations in uniformity among the light-emitting points in a Micro-LED array, obtaining information on the luminous intensity of each point and performing uniformity correction are also key steps in improving display quality.

[0004] Currently, existing methods for measuring light emission angles primarily rely on light intensity distribution meters or spectroradiometers. However, these devices are not only expensive and complex to operate, but also require mechanical rotation. This severely limits their application in measuring micro-LED light emission angles. Furthermore, due to the extremely small size of micro-LEDs, crosstalk between individual sub-light points is a significant issue during measurement, significantly impacting the accuracy of light emission angle and luminous uniformity measurements.

[0005] In summary, Micro-LED display technology currently faces numerous challenges in measuring light output angle and uniformity. A new measurement method and system suitable for Micro-LED arrays is urgently needed to overcome the shortcomings of existing technologies and enhance the overall performance and application scope of Micro-LED display technology. Summary of the Invention

[0006] To this end, an embodiment of the present invention provides a Micro-LED array measurement method and system based on phase reconstruction, which is used to solve the problems in the prior art of inaccurate Micro-LED light output angle measurement, difficult light uniformity evaluation, and complex and costly measurement process.

[0007] To solve the above problems, an embodiment of the present invention provides a Micro-LED array measurement method based on phase reconstruction. The method is applied to a computer in a measurement system, including:

[0008] Acquire a focus plane image and multiple out-of-focus plane images of the Micro-LED array to be tested;

[0009] Performing phase reconstruction on the focus plane image and the multiple defocus plane images using a phase reconstruction model to obtain light field information of the light-emitting surface of the Micro-LED array to be tested;

[0010] Based on the light field information of the light emitting surface, constructing the amplitude-frequency distribution of the light emitting surface, and obtaining light intensity distribution evaluation diagrams at different light emitting angles;

[0011] Based on the focus plane image and the light intensity distribution evaluation diagram, measurement information of the Micro-LED array to be measured is obtained; wherein the measurement information includes at least one of the light output angle, the luminous intensity ratio, and the light intensity uniformity.

[0012] The beneficial effects of this technical solution are as follows: the measurement method provided by the present invention first obtains a focus plane image and multiple through-focus plane images of the Micro-LED array to be tested; then processes them using a phase reconstruction model, which can infer phase information from light intensity information, thereby obtaining light field information of the light-emitting surface; constructs an amplitude-frequency distribution based on the light field information to obtain light intensity distribution evaluation maps at different light-emitting angles; and uses the focus plane image and light intensity distribution evaluation map to obtain measurement information of the Micro-LED array to be tested (including at least one of the light-emitting angle, luminous intensity ratio, and light intensity uniformity). This not only enables the detection of the Micro-LED array to be tested, but also allows for rapid and accurate detection of information such as the light-emitting angle, luminous intensity ratio, and light intensity uniformity of the Micro-LED array to be tested. Moreover, this measurement principle is not limited to Micro-LED arrays. For other light-emitting semiconductor materials, as long as their focus plane and through-focus plane light intensity images can be obtained, this method can be applied to measure, such as analyzing their light-emitting angle, luminous intensity, and uniformity. This provides a universal solution for the detection of light-emitting semiconductor materials and can be widely applied to the measurement of other light-emitting semiconductor materials.

[0013] Preferably, the method for constructing the amplitude-frequency distribution of the light-emitting surface based on the light field information of the light-emitting surface is:

[0014] A coordinate system is constructed with the light-emitting surface of the Micro-LED array to be measured as a reference; wherein the light-emitting surface is assumed to be located in the xOy plane and light propagates along the positive direction of the z axis;

[0015] Obtaining spatial distribution information of light emitted by the Micro-LED array to be measured in the coordinate system;

[0016] Based on the first angle, the second angle and the distribution information, the amplitude frequency distribution of the light-emitting surface is obtained; wherein the first angle is the angle between the projection of the light propagation direction on the xOz plane and the positive direction of the z axis. , the second angle is the angle between the projection of the light propagation direction on the yOz plane and the positive direction of the z axis. , the light propagation direction is the propagation direction of the light emitted by the Micro-LED array to be tested.

[0017] Preferably, obtaining the amplitude-frequency distribution of the light-emitting surface based on the first angle, the second angle and the distribution information includes:

[0018] Obtaining distribution information at each of the spatial locations;

[0019] Calculating adjustment information at each of the spatial positions based on the first angle, the second angle, and each of the spatial positions;

[0020] Based on the product of the distribution information at each of the spatial positions and the corresponding adjustment information, the amplitude-frequency distribution of the light-emitting surface is obtained.

[0021] Preferably, calculating the adjustment information at each spatial position based on the first angle, the second angle, and each spatial position includes:

[0022] Processing the first angle and the second angle respectively to obtain a first coefficient and a second coefficient; wherein the first coefficient is related to the first angle and the wavelength of light emitted by the Micro-LED array to be measured, and the second coefficient is related to the second angle and the wavelength of light emitted by the Micro-LED array to be measured;

[0023] The first coefficient and the second coefficient are processed to obtain the adjustment information; wherein the adjustment information is related to the first coefficient, the second coefficient and the spatial position.

[0024] Preferably, the amplitude-frequency distribution of the light-emitting surface is The calculation formula is:

[0025] ;

[0026] Where, is the coordinate of the spatial position, is the distribution information at the spatial position (x, y), is the spatial frequency, is the wavelength, Is an imaginary unit.

[0027] Preferably, obtaining measurement information of the Micro-LED array to be measured based on the focus plane image and the light intensity distribution evaluation diagram includes:

[0028] Obtaining a grayscale value for each pixel in the focal plane image and calculating a root mean square error (RMSE) of all the grayscale values; and determining the light intensity uniformity of the Micro-LED array to be tested based on the RMS error; wherein the smaller the RMS error, the better the light intensity uniformity of the Micro-LED array to be tested;

[0029] and / or processing the light intensity distribution evaluation graph to obtain a peak value of light intensity and an angular range corresponding to light of different intensities; and obtaining a light emission angle of the Micro-LED array to be tested based on the peak value of light intensity and the angular range corresponding to light of different intensities;

[0030] And / or, processing the light intensity distribution evaluation diagram to obtain light intensities at different angles; calculating the sum of the light intensities at all angles within a preset angle range to obtain the local light intensity sum; calculating the ratio of the local light intensity sum to the total light intensity of the light emitted by the Micro-LED array to be tested to obtain the luminous intensity ratio.

[0031] Preferably, the measurement system further comprises a focusing lens device, a microscope objective lens and an image sensor. Before performing phase reconstruction on the focus plane image and the multiple out-of-focus plane images, the method further comprises:

[0032] Calibrate the focusing lens device, the microscope objective lens, and the image sensor;

[0033] Establishing an error correction model based on the calibrated focusing lens device, the microscope objective lens, and the image sensor; wherein the error correction model is used to correct aberrations introduced by the focusing lens device, the microscope objective lens, and the image sensor;

[0034] Acquire a focus plane image to be corrected and a plurality of defocus plane images to be corrected of the Micro-LED array to be tested sent by the image sensor;

[0035] The error correction model is used to correct the focus surface image to be corrected and each of the defocus surface images to be corrected, so as to obtain the corresponding focus surface image and the multiple defocus surface images.

[0036] Preferably, the measurement system further comprises a focusing lens device, and the method further comprises:

[0037] Acquire initial surface polynomial parameters of the focusing lens component and initial model parameters of the phase reconstruction model; wherein the initial surface polynomial parameters are initial values of the surface polynomial parameters of the focusing lens component, and the initial model parameters are initial values of the model parameters of the phase reconstruction model;

[0038] Simulating and generating a plurality of defocused surface light intensity signal images under the initial surface polynomial parameters, and performing phase reconstruction on the plurality of defocused surface light intensity signal images based on the initial model parameters using the phase reconstruction model to obtain reconstructed phase distribution data;

[0039] Constructing a loss function based on the reconstructed phase distribution data and the ideal phase distribution data at the corresponding position, jointly optimizing the surface polynomial parameters of the focusing lens device and the model parameters of the phase reconstruction model through a back propagation algorithm, iteratively optimizing until the loss function converges, and obtaining optimized surface polynomial parameters and optimized model parameters;

[0040] Using the optimized surface polynomial parameters as actual operating parameters of the focusing lens device, and using the optimized model parameters as final model parameters of the phase reconstruction model;

[0041] Preferably, the calculation formula of the loss function is as follows:

[0042] ;

[0043] in, represents the root mean square error, Indicates the total number of pixels in the vertical direction of the out-of-focus light intensity signal image; Indicates the total number of pixels in the horizontal direction of the out-of-focus light intensity signal image; is the pixel position The reconstructed phase value of is the pixel position The ideal phase value.

[0044] The beneficial effects of this technical solution are as follows: on the one hand, the focusing lens component, microscope objective, and image sensor are calibrated before measurement, and an error correction model is established to correct aberrations. On the other hand, by obtaining the initial surface polynomial parameters of the focusing lens component and the initial model parameters of the phase reconstruction model, a simulation is generated to generate an image of the defocused plane light intensity signal, and phase reconstruction is performed to obtain reconstructed phase distribution data. A loss function is constructed, and the backpropagation algorithm is used to jointly optimize the focusing lens component surface polynomial parameters and the phase reconstruction model parameters. The optimization parameters are iterated until the loss function converges to obtain the optimized parameters. These measures effectively reduce measurement errors and improve the accuracy and reliability of the measurement.

[0045] An embodiment of the present invention further provides a measurement system, which includes a computer, and the computer is used to implement the above-mentioned Micro-LED array measurement method based on phase reconstruction.

[0046] Preferably, the measurement system further comprises:

[0047] A first displacement platform is used to move the Micro-LED array to be tested in the x-axis direction and the y-axis direction;

[0048] a stage, disposed on the first displacement platform, for carrying and adjusting the pitch angle of the light-emitting surface of the Micro-LED array to be measured so that the light-emitting surface of the Micro-LED array is perpendicular to the optical axis of the measurement system;

[0049] A focusing lens device is provided on the outgoing light path of the Micro-LED array to be tested, and is used to separate and converge the crosstalk of light beams generated by adjacent light-emitting units in the Micro-LED array to be tested;

[0050] A microscope objective lens is provided on the outgoing light path of the focusing lens device and is used to amplify the light beam converged by the focusing lens device;

[0051] an image sensor, disposed on an outgoing light path of the microscope objective lens and mechanically connected to the microscope objective lens, for receiving and recording light intensity information magnified by the microscope objective lens to obtain the in-focus plane image and the multiple out-of-focus plane images;

[0052] The second displacement platform is used to adjust the height of the microscope objective lens and the image sensor in the z-axis direction. The second displacement platform is connected to both sides of the image sensor through an adapter plate.

[0053] Preferably, the accuracy of the first displacement platform reaches ±10 μm, the travel of the first displacement platform is greater than the size of the Micro-LED array to be measured, and the aperture of the focusing lens device is more than three times the size of the Micro-LED array to be measured; the accuracy of the second displacement platform reaches ±1 μm, and the travel of the second displacement platform is greater than three times the focal depth of the microscope objective lens;

[0054] And / or, the numerical aperture of the microscope objective lens is greater than the numerical aperture of the focusing lens component.

[0055] The beneficial effects of this technical solution are as follows: the measurement system provided by the present invention includes a first displacement platform, a stage, a focusing lens device, a microscope objective lens, an image sensor, and a second displacement platform. The first displacement platform has an accuracy of ±10μm and a stroke greater than the size of the Micro-LED array to be measured, and can accurately move the Micro-LED array to be measured; the stage can adjust the pitch angle of the light-emitting surface of the Micro-LED array to be measured so that it is perpendicular to the optical axis; the aperture of the focusing lens device is more than 3 times the size of the Micro-LED array to be measured, and can separate and converge the crosstalk of the adjacent light-emitting units; the microscope objective lens amplifies the converged light beam; the image sensor receives and records the light intensity information; the second displacement platform has an accuracy of ±1μm and a stroke greater than 3 times the focal depth of the microscope objective lens, and can accurately adjust the height of the microscope objective lens and the image sensor to obtain images of the focal plane and the defocused plane. The entire system is compact and reasonably designed, and can realize an automated measurement process. It is suitable for batch detection of large-scale Micro-LED arrays and greatly improves detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the implementation cases of the present invention or the technical solutions in the prior art, the following is a brief description of the drawings required for use in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be understood as limiting the present invention in any way. Those skilled in the art can derive other drawings based on these drawings without inventive effort. Among them:

[0057] Figure 1 A flow chart of a Micro-LED array measurement method based on phase reconstruction provided by the present invention;

[0058] Figure 2 This is a structural diagram of a measurement system provided by the present invention.

[0059] Figure numerals in the specification: 1. first displacement platform; 2. stage; 3. focusing lens device; 4. microscope objective lens; 5. image sensor; 6. second displacement platform; 7. computer. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0061] Example 1:

[0062] In order to solve the problems of inaccurate measurement of Micro-LED light angle, difficulty in evaluating light uniformity, and complex and costly measurement process in the existing technology. Figure 1 As shown, the present invention proposes a Micro-LED array measurement method based on phase reconstruction, comprising:

[0063] S1: Acquire a focus plane image and multiple out-of-focus plane images of the Micro-LED array to be tested.

[0064] The Micro-LED array under test is the one that needs to be tested. In optical measurement, directly obtaining phase information of the light field is difficult, while light intensity information is relatively easy to measure. For the Micro-LED array under test, light intensity information can be obtained from its focused plane image and multiple through-focus plane images. The focused plane image and through-focus plane images contain rich information (light intensity information) about the light emitted by the Micro-LED array under test. These images are the key data foundation for phase reconstruction using the phase reconstruction model.

[0065] S2: Use the phase reconstruction model to perform phase reconstruction on the focused surface image and multiple defocused surface images to obtain the light field information of the light-emitting surface of the Micro-LED array to be tested.

[0066] To gain a deeper understanding of the light characteristics of the Micro-LED array under test, phase information of the light field is crucial. This is because phase plays a key role in light interference, diffraction, and other phenomena, determining the propagation and interaction characteristics of light. Therefore, a phase reconstruction model is required to infer phase information from known light intensity information, thereby obtaining complete light field information. Based on the in-focus plane image and all out-of-focus plane images, the phase reconstruction model can obtain light field information of the light-emitting surface, supporting subsequent analysis.

[0067] Specifically, common phase reconstruction models use algorithms such as the Gerchberg-Saxton iterative algorithm, the light intensity transmission equation, or deep learning algorithms. The Gerchberg-Saxton iterative algorithm performs iterative calculations based on Fourier transforms and constraints, gradually approximating the true phase distribution by repeatedly converting between the spatial and frequency domains. The light intensity transmission equation recovers the phase by solving partial differential equations based on the relationship between light intensity changes and phase during light propagation. Deep learning algorithms use large amounts of data to train models, allowing the model to learn the complex mapping relationship between light intensity information and phase information, thereby achieving phase reconstruction. In practical applications, the appropriate algorithm model can be selected based on factors such as measurement requirements, data characteristics, and computing resources.

[0068] Furthermore, the light intensity information of the acquired focal plane image and all defocused plane images is input into the selected phase reconstruction algorithm model. The algorithm model analyzes and processes this light intensity information based on its own principles and computational logic. Taking the Gerchberg-Saxton iterative algorithm as an example, a preliminary Fourier transform is first performed on the light intensity information to obtain an initial phase estimate. Then, based on the constraints of the focal plane and defocus plane, the phase estimate is continuously iteratively updated between the spatial domain and the frequency domain until certain convergence conditions are met, resulting in more accurate phase information. By combining the phase information with the known light intensity information, the light field information of the light-emitting surface of the Micro-LED array under test can be constructed.

[0069] The light field information of the light-emitting surface includes the amplitude and phase distribution of light, which is crucial for fully understanding the light emission characteristics of the Micro-LED array. Based on this light field information, we can further construct the amplitude-frequency distribution data of the light-emitting surface and obtain light intensity distribution evaluation diagrams at different light emission angles.

[0070] S3: Based on the light field information of the light emitting surface, the amplitude-frequency distribution data of the light emitting surface is constructed to obtain the light intensity distribution evaluation diagram at different light emitting angles.

[0071] S4: Based on the focal plane image and the light intensity distribution evaluation diagram, measurement information of the Micro-LED array to be measured is obtained, where the measurement information of the Micro-LED array to be measured includes at least one of a light output angle, a luminous intensity ratio, and a light intensity uniformity.

[0072] As can be seen from the above technical solution, the present invention proposes a Micro-LED array measurement method based on phase reconstruction. First, a focus plane image and multiple out-of-focus plane images of the Micro-LED array to be measured are obtained. This step can quickly obtain basic data. Then, these images are processed using a phase reconstruction model to obtain light field information of the light-emitting surface. This process, with the help of advanced algorithms, can effectively improve the accuracy and reliability of the measurement. Next, amplitude-frequency distribution data is constructed based on the light field information to obtain a light intensity distribution evaluation diagram for different light-emitting angles, thereby accurately presenting the light characteristics. Finally, by combining the focus plane image with the light intensity distribution evaluation diagram, measurement information such as light-emitting angle, luminous intensity ratio and light intensity uniformity is obtained, thereby achieving a comprehensive evaluation of the Micro-LED array to be measured. This method is not only suitable for batch detection of large-scale Micro-LED arrays, greatly improving detection efficiency, but can also be widely used in the measurement of other light-emitting semiconductor materials, providing an efficient and stable batch product detection solution for the field of automated detection of light-emitting semiconductor materials, and effectively solving the problems of inaccurate measurement, difficult evaluation, complex process and high cost in the existing technology.

[0073] Furthermore, based on the light field information of the light emitting surface, a method for constructing the amplitude-frequency distribution data of the light emitting surface includes:

[0074] S31: Construct a coordinate system based on the light-emitting surface of the Micro-LED array.

[0075] Assuming the light-emitting surface is located in the xOy plane, the light propagates along the positive direction of the z-axis, and the light emitted by the Micro-LED array can be parallel or non-parallel to the z-axis.

[0076] S32: Obtaining spatial distribution information of light emitted from the Micro-LED array to be measured in the coordinate system.

[0077] S34: Obtaining amplitude-frequency distribution data of the light-emitting surface based on the first angle, the second angle, and the distribution information.

[0078] The first angle is the angle between the projection of the light propagation direction on the xOz plane and the positive direction of the z axis. The second angle is the angle between the projection of the light propagation direction on the yOz plane and the positive direction of the z axis. .

[0079] Furthermore, based on the first angle, the second angle and the distribution information, the amplitude-frequency distribution data of the light-emitting surface is obtained, including:

[0080] S341: Obtain distribution information at each spatial location.

[0081] S342: Calculate adjustment information at each spatial position based on the first angle, the second angle, and each spatial position.

[0082] The following methods can be used:

[0083] (A1) The first angle and the second angle are processed respectively to obtain a first coefficient and a second coefficient.

[0084] The first coefficient is related to the first angle and the wavelength of light emitted by the Micro-LED array to be measured, and the second coefficient is related to the second angle and the wavelength of light emitted by the Micro-LED array to be measured.

[0085] (A2) Processing the first coefficient and the second coefficient to obtain adjustment information.

[0086] The adjustment information is related to the first coefficient, the second coefficient, and the spatial position. Specifically, the calculation formula of the adjustment information F(x, y) is as follows:

[0087] ;

[0088] in, is the coordinate of the spatial position, is the wavelength, is the imaginary unit, is the first coefficient, is the second coefficient, is the spatial frequency.

[0089] S343: Obtaining the amplitude-frequency distribution of the light emitting surface based on the product of the distribution information at each spatial position and the corresponding adjustment information.

[0090] Based on the product of the distribution information at each spatial position and the corresponding adjustment information, the amplitude-frequency distribution of the light-emitting surface is obtained, thereby converting the spatial distribution characteristics of the light field into the frequency domain for analysis. Specifically, the amplitude-frequency distribution of the light-emitting surface The calculation formula is:

[0091] ;

[0092] Where, is the coordinate of the spatial position, For spatial location The distribution information of To adjust the information, is the wavelength, Is an imaginary unit.

[0093] Furthermore, the amplitude-frequency distribution reflects the distribution of different spatial frequency components in the light field. Since there is a corresponding relationship between spatial frequency and light output angle, a light intensity distribution evaluation diagram for different light output angles can be constructed.

[0094] In one embodiment, the measurement information of the Micro-LED array to be measured includes light intensity uniformity, and the light intensity uniformity evaluation method includes:

[0095] S41a: Obtain the grayscale value of each pixel in the focal plane image and calculate the root mean square error of the grayscale values.

[0096] S42a: Determine the light intensity uniformity of the Micro-LED array to be measured based on the root mean square error.

[0097] The smaller the RMS error value, the better the light intensity uniformity of the Micro-LED array under test. For example, multiple levels can be set for the light intensity uniformity of the Micro-LED array under test, and each level corresponds to a RMS error value range, as shown in Table 1 below:

[0098] Table 1 Relationship between the value range of the root mean square error and the level of light intensity uniformity

[0099] The numerical range of the root mean square error Level of light intensity uniformity [R1, R2) Very uniform [R2, R3) Generally uniform [R3, R4) Uneven

[0100] It is worth noting that if a point with a large difference in grayscale value appears, the corresponding luminous point position can be located by finding the coordinates of the point, and uniformity correction can be performed by adjusting the voltage of the luminous point.

[0101] In one embodiment, the measurement information of the Micro-LED array to be measured includes the light output angle. Since the light intensity distribution evaluation diagram reflects the light intensity distribution at different light output angles, the methods that can be used to obtain the light output angle include:

[0102] S41b: Processing the light intensity distribution evaluation graph to obtain the peak value of the light intensity and the angular ranges corresponding to the light of different intensities.

[0103] S42b: Based on the peak value of the light intensity and the angle range corresponding to the light of different intensities, the light output angle of the Micro-LED array to be tested is obtained.

[0104] The specific implementation involves processing the evaluation map data, such as finding the extreme point of the light intensity distribution curve, determining the corresponding angle as the main light output angle, or determining the range of the light output angle according to the set light intensity threshold, etc., which is similar to the relevant technology and will not be repeated here.

[0105] In one embodiment, the measurement information of the Micro-LED array to be measured includes a luminous intensity ratio, and a method for obtaining the luminous intensity ratio includes:

[0106] S41c: Process the light intensity distribution evaluation diagram to obtain light intensities at different angles; calculate the sum of the light intensities at all angles within a preset angle range to obtain the local light intensity sum.

[0107] S42c: Calculate the ratio of the local light intensity to the total light intensity of the light emitted by the Micro-LED array to obtain the luminous intensity ratio.

[0108] When calculating the total light intensity, it is necessary to integrate or sum the light intensities corresponding to all angles in the light intensity distribution evaluation diagram. For example, assuming that the light output angle range is divided into k (k ≥ 2) sub-intervals , first calculate the light intensity in each subinterval , total light intensity , then a subinterval The luminous intensity ratio is .

[0109] In summary, the measurement method provided by the present invention can quickly and cost-effectively detect the light output angle, luminous intensity ratio, and light intensity uniformity of the measured Micro-LED array after collimation control. This testing method can also provide efficient and stable batch product testing in the field of automated testing of light-emitting semiconductor materials.

[0110] Example 2:

[0111] like Figure 2As shown, the present invention provides a measurement system, which includes a computer 7 for implementing the above-mentioned phase reconstruction-based Micro-LED array measurement method. In addition, the measurement system also includes a first displacement platform 1, an object stage 2, a focusing lens device 3, a microscope objective lens 4, an image sensor 5, and a second displacement platform 6.

[0112] The first displacement platform 1 is used to move the Micro-LED array under test in the x- and y-axis directions. Specifically, in this embodiment, the first displacement platform 1 is required to have an accuracy of ±10μm and a travel range greater than the size of the Micro-LED array under test. This ensures that the position of the Micro-LED array under test can be precisely controlled during the measurement process, and that each portion of the Micro-LED array under test can be moved to the appropriate position in the measurement optical path to obtain accurate and comprehensive measurement data.

[0113] The stage 2 is mounted on the first displacement platform 1 and is used to support and adjust the pitch angle of the light-emitting surface of the Micro-LED array under test, ensuring that the light-emitting surface of the Micro-LED array is perpendicular to the optical axis of the measurement system. Specifically, the pitch angle of the light-emitting surface of the Micro-LED array under test can be adjusted using a three-point adjustment method, but this method is not limited to this method.

[0114] Focusing lens device 3 is positioned in the outgoing light path of the Micro-LED array under test, and is used to separate and converge the crosstalk between the light beams generated by adjacent light-emitting units in the Micro-LED array under test. Specifically, in this embodiment, the aperture of focusing lens device 3 is at least three times the size of the Micro-LED array under test. This allows for better collection and processing of light emitted by the Micro-LED array under test, reduces light loss and edge effects, and improves imaging quality and measurement accuracy.

[0115] The microscope objective lens 4 is arranged on the outgoing light path of the focusing lens device 3 and is used to amplify the light beam converged by the focusing lens device 3 .

[0116] The image sensor 5 is arranged on the outgoing light path of the microscope objective lens 4 and is mechanically connected to the microscope objective lens 4 for receiving and recording the light intensity information magnified by the microscope objective lens 4 to obtain a focus plane image and multiple out-of-focus plane images.

[0117] Furthermore, in this embodiment, the numerical aperture of the microscope objective 4 is larger than the numerical aperture of the focusing lens device 3. Numerical aperture is an important parameter for measuring the ability of an optical system to collect light. The larger the numerical aperture, the more light the optical system can collect, the higher the resolution, and the better the imaging quality. In this measurement system, the microscope objective 4 needs to further amplify and image the light processed by the focusing lens device 3, so that the image sensor 5 can accurately record light intensity information for subsequent phase reconstruction and light field information analysis operations. If the numerical aperture of the microscope objective 4 is smaller than the focusing lens device 3, the light converged by the focusing lens device 3 may not be fully received and processed by the microscope objective 4, resulting in a decrease in imaging quality and loss or distortion of light field information, thereby affecting the accurate measurement of parameters such as the light output angle and uniformity of the Micro-LED array.

[0118] The second displacement platform 6 is used to adjust the height of the microscope objective lens 4 and the image sensor 5 in the z-axis direction. The second displacement platform 6 is connected to both sides of the image sensor 5 via an adapter plate. Specifically, in this embodiment, the second displacement platform 6 is required to have an accuracy of ±1μm and a travel range greater than three times the focal depth of the microscope objective lens 4. The high-precision second displacement platform 6 facilitates more precise adjustment of the relative position of the microscope objective lens 4 and the image sensor 5 when acquiring in-focus and out-of-focus images, thereby obtaining more accurate light intensity information, providing a reliable data foundation for subsequent phase reconstruction and performance analysis.

[0119] Furthermore, using the measurement system of the present invention to obtain a focus plane image and multiple out-of-focus plane images of the Micro-LED array to be measured is an important basic link in the measurement process, and its operation process includes the following steps:

[0120] (1) First, mount the Micro-LED array to be tested on stage 2 and precisely adjust the pitch angle of its light-emitting surface so that the light-emitting surface of the Micro-LED array to be tested is strictly perpendicular to the optical axis of the measurement system. This ensures that the light emitted by the Micro-LED array to be tested can enter the subsequent optical components in the correct direction. Then, light up the Micro-LED array to be tested and use the first displacement platform 1 to accurately move it to the measurement position.

[0121] (2) Focusing lens device 3 focuses the light beam emitted by the Micro-LED array to be tested, separating and converging the crosstalk of the light beams generated by adjacent light-emitting units for subsequent processing. The light beam emitted by the Micro-LED array to be tested then enters microscope objective lens 4, which amplifies the converged light beam.

[0122] (3) The image sensor 5 is moved by the second displacement platform 6 so that the image sensor 5 is located at the optimal focal plane position where the microscope objective lens 4 converges; the image sensor 5 receives and records the light intensity information magnified by the microscope objective lens 4, and the image obtained at this time is the focal plane image.

[0123] (4) The height of the microscope objective lens 4 and the image sensor 5 in the z-axis direction is adjusted by the second displacement platform 6, thereby changing the relative position of the two and placing the image sensor 5 in different defocus positions. At each defocus position, the image sensor 5 receives and records the corresponding light intensity information, thereby obtaining multiple defocused surface images.

[0124] In addition, in order to further improve the measurement accuracy, the method of the present invention can pre-calibrate the focusing lens device 3, the microscope objective lens 4 and the camera image sensor 5 before phase reconstruction of the focus plane image and multiple defocus plane images, so as to better analyze and correct the errors that may be introduced by them. Specifically, the method includes the following steps:

[0125] (B1) Calibrate the focusing lens device 3, the microscope objective lens 4 and the image sensor 5.

[0126] (B2) An error correction model is established based on the calibrated focusing lens device 3, microscope objective lens 4 and image sensor 5.

[0127] The error correction model is used to correct the aberrations introduced by the focusing lens device 3 , the microscope objective lens 4 and the image sensor 5 .

[0128] (B3) Acquire the focus plane image to be corrected and multiple defocus plane images to be corrected of the Micro-LED array to be tested sent by the image sensor 5.

[0129] (B4) Using an error correction model, the focus surface image to be corrected and each defocus surface image to be corrected are corrected respectively to obtain a corresponding focus surface image and multiple defocus surface images.

[0130] In addition to the above-mentioned pre-calibration and post-correction methods, the present invention can also take aberrations into account during the design process of the focusing lens device 3. By continuously optimizing the parameters of the focusing lens device 3 and the parameters of the phase reconstruction model, the difference between the final reconstructed phase and the theoretical phase is minimized. Specifically, by constructing a root mean square error loss function, the parameters of the focusing lens device 3 and the phase reconstruction model are jointly optimized to find the optimal combination of device parameters and model parameters. The specific steps include:

[0131] (C1) Obtaining initial surface polynomial parameters of the focusing lens device 3 and initial model parameters of the phase reconstruction model.

[0132] The initial surface polynomial parameters are initial values of the surface polynomial parameters of the focusing lens device 3 , and the initial model parameters are initial values of the model parameters of the phase reconstruction model.

[0133] The surface shape of the focusing lens device 3 is not a simple sphere or plane. In order to accurately describe its complex shape, polynomials are often used for fitting. A surface polynomial is a mathematical expression that approximates the actual lens surface shape through a combination of different terms. The coefficients of each term are the so-called surface polynomial parameters. Taking the commonly used Zernike polynomials as an example, it is widely used in the field of optics to describe the surface shape of optical elements. The Zernike polynomials are composed of a series of functions with a specific mathematical form. By adjusting the coefficients of each term in the polynomial, the surface shape of the focusing lens device 3 can be accurately described. These coefficients are the device parameters. Different parameter values correspond to different surface shapes, and the surface shape will affect the lens's refraction, focusing, and other effects on light, thereby affecting the performance of the entire measurement system, such as the converging effect of the light beam, the clarity of the imaging, etc.

[0134] (C2) Simulating and generating multiple defocused surface light intensity signal images under the initial surface polynomial parameters, and using the phase reconstruction model to reconstruct the phases of the multiple defocused surface light intensity signal images based on the initial model parameters to obtain reconstructed phase distribution data.

[0135] (C3) Constructing a loss function based on the reconstructed phase distribution data and the ideal phase distribution data at the corresponding position, jointly optimizing the surface polynomial parameters of the focusing lens device 3 and the model parameters of the phase reconstruction model through the back propagation algorithm, iteratively optimizing until the loss function converges, and obtaining the optimized surface polynomial parameters and the optimized model parameters.

[0136] The ideal phase distribution is generated through physical optics model simulation, and the loss function is calculated based on the phase distribution data in the form of a two-dimensional matrix.

[0137] Furthermore, the loss function is used to quantify the deviation between the reconstructed phase and the ideal phase, and to guide the joint optimization of the parameters of the focusing lens device 3 and the model parameters of the phase reconstruction model. The calculation formula of the loss function is as follows:

[0138] ;

[0139] in, represents the root mean square error, Indicates the total number of pixels in the vertical direction of the out-of-focus light intensity signal image; Indicates the total number of pixels in the horizontal direction of the out-of-focus light intensity signal image; is the pixel position The reconstructed phase value of is the pixel position The ideal phase value.

[0140] (C4) Using the optimized surface polynomial parameters as the actual working parameters of the focusing lens device 3, and using the optimized model parameters as the final model parameters of the phase reconstruction model.

[0141] By minimizing the loss function, the present invention can find the optimal combination of device parameters (i.e., the actual operating parameters of the focusing lens device 3) and model parameters (i.e., the final model parameters of the phase reconstruction model), thereby optimizing the entire measurement system and improving the accuracy of measuring the light output angle and uniformity of the Micro-LED array to be measured.

[0142] The technical solution provided by the present invention has the following advantages:

[0143] (1) Accurately measure multiple parameters: The measurement method provided by the present invention first obtains the focal plane image and multiple defocused plane images of the Micro-LED array to be tested, and then uses the phase reconstruction model for processing. It can infer the phase information from the light intensity information, and then obtain the light field information of the light-emitting surface. Based on the light field information, the amplitude-frequency distribution is constructed to obtain the light intensity distribution evaluation map at different light-emitting angles. The root mean square error of the pixel grayscale value is calculated by the focal plane image to evaluate the light intensity uniformity; the light intensity peak value and the angle range corresponding to different intensities of light are obtained from the light intensity distribution evaluation map to determine the light-emitting angle; the light intensity in the preset angle range and the ratio of the total light intensity are calculated to obtain the luminous intensity ratio. These steps are closely linked, which can not only realize the detection of the Micro-LED array to be tested, but also quickly and accurately detect the light-emitting angle, luminous intensity ratio, light intensity uniformity and other information of the Micro-LED array to be tested.

[0144] (2) Suitable for batch testing: The measurement system provided by the present invention includes a first displacement platform, a stage, a focusing lens device, a microscope objective lens, an image sensor, and a second displacement platform. The first displacement platform has an accuracy of ±10μm and a stroke greater than the size of the Micro-LED array to be measured, and can accurately move the array; the stage can adjust the pitch angle of the array light-emitting surface to make it perpendicular to the optical axis; the focusing lens device has an aperture greater than 3 times the array size and can separate and converge the crosstalk of the adjacent light-emitting units; the microscope objective lens amplifies the converged light beam; the image sensor receives and records light intensity information; the second displacement platform has an accuracy of ±1μm and a stroke greater than 3 times the focal depth of the microscope objective lens, and can accurately adjust the height of the microscope objective lens and the image sensor to obtain images of the focal plane and the defocused plane. The entire system is compact and reasonable in design, and can realize an automated measurement process. It is suitable for batch testing of large-scale Micro-LED arrays and greatly improves detection efficiency.

[0145] (3) Improve measurement accuracy and reliability: On the one hand, the focusing lens device, microscope objective lens, and image sensor are calibrated before measurement, and an error correction model is established to correct aberrations. On the other hand, by obtaining the initial surface polynomial parameters of the focusing lens device and the initial model parameters of the phase reconstruction model, a simulation is generated to generate a defocused surface light intensity signal image, and phase reconstruction is performed to obtain reconstructed phase distribution data. A loss function is constructed, and the back propagation algorithm is used to jointly optimize the focusing lens device surface polynomial parameters and the phase reconstruction model parameters. The parameters are iterated until the loss function converges to obtain the optimized parameters. These measures effectively reduce measurement errors and improve measurement accuracy and reliability.

[0146] (4) Wide range of applications: The core of the phase reconstruction-based measurement method of the present invention is to obtain light field phase information from light intensity information, and then analyze the luminescence characteristics. This measurement principle is not limited to Micro-LED arrays. For other light-emitting semiconductor materials, as long as the light intensity images of their focal plane and defocused plane can be obtained, the method can be applied to measure, such as analyzing their light output angle, luminous intensity and uniformity. This provides a universal solution for the detection of light-emitting semiconductor materials and can be widely applied to the measurement of other light-emitting semiconductor materials.

[0147] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0148] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0149] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0150] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

Claims

1. A Micro-LED array measurement method based on phase reconstruction, characterized in that: Applied to a computer in a measurement system, the method comprises: Acquire a focus plane image and multiple out-of-focus plane images of the Micro-LED array to be tested; Performing phase reconstruction on the focus plane image and the multiple defocus plane images using a phase reconstruction model to obtain light field information of the light-emitting surface of the Micro-LED array to be tested; Based on the light field information of the light emitting surface, constructing the amplitude-frequency distribution of the light emitting surface, and obtaining light intensity distribution evaluation diagrams at different light emitting angles; Based on the focus plane image and the light intensity distribution evaluation diagram, measurement information of the Micro-LED array to be measured is obtained; wherein the measurement information includes at least one of the light output angle, the luminous intensity ratio, and the light intensity uniformity.

2. The Micro-LED array measurement method based on phase reconstruction according to claim 1, characterized in that: The method for constructing the amplitude-frequency distribution of the light-emitting surface based on the light field information of the light-emitting surface is: A coordinate system is constructed with the light-emitting surface of the Micro-LED array to be measured as a reference; wherein the light-emitting surface is assumed to be located in the xOy plane and light propagates along the positive direction of the z axis; Obtaining spatial distribution information of light emitted by the Micro-LED array to be measured in the coordinate system; Based on the first angle, the second angle and the distribution information, the amplitude-frequency distribution of the light-emitting surface is obtained; wherein, the first angle is the angle α between the projection of the light propagation direction on the xOz plane and the positive direction of the z-axis, the second angle is the angle β between the projection of the light propagation direction on the yOz plane and the positive direction of the z-axis, and the light propagation direction is the propagation direction of light emitted by the Micro-LED array to be tested.

3. The Micro-LED array measurement method based on phase reconstruction according to claim 2, characterized in that: The obtaining of the amplitude-frequency distribution of the light-emitting surface based on the first angle, the second angle and the distribution information includes: Obtaining distribution information at each of the spatial locations; Calculating adjustment information at each of the spatial positions based on the first angle, the second angle, and each of the spatial positions; Based on the product of the distribution information at each of the spatial positions and the corresponding adjustment information, the amplitude-frequency distribution of the light-emitting surface is obtained.

4. The Micro-LED array measurement method based on phase reconstruction according to claim 3, characterized in that: The calculating adjustment information at each of the spatial positions based on the first angle, the second angle, and each of the spatial positions includes: Processing the first angle and the second angle respectively to obtain a first coefficient and a second coefficient; wherein the first coefficient is related to the first angle and the wavelength of light emitted by the Micro-LED array to be measured, and the second coefficient is related to the second angle and the wavelength of light emitted by the Micro-LED array to be measured; The first coefficient and the second coefficient are processed to obtain the adjustment information; wherein the adjustment information is related to the first coefficient, the second coefficient and the spatial position.

5. The Micro-LED array measurement method based on phase reconstruction according to claim 4, characterized in that: Amplitude-frequency distribution of the light-emitting surface The calculation formula is: In the formula, x and y are the coordinates of the spatial position, U(x,y) is the distribution information at the spatial position (x,y), is the spatial frequency, λ is the wavelength, and j is the imaginary unit.

6. The Micro-LED array measurement method based on phase reconstruction according to claim 1, characterized in that: The obtaining measurement information of the Micro-LED array to be measured based on the focus plane image and the light intensity distribution evaluation diagram includes: Obtaining a grayscale value for each pixel in the focal plane image and calculating a root mean square error (RMSE) of all the grayscale values; and determining the light intensity uniformity of the Micro-LED array to be tested based on the RMS error; wherein the smaller the RMS error, the better the light intensity uniformity of the Micro-LED array to be tested; and / or processing the light intensity distribution evaluation graph to obtain a peak value of light intensity and an angular range corresponding to light of different intensities; and obtaining a light emission angle of the Micro-LED array to be tested based on the peak value of light intensity and the angular range corresponding to light of different intensities; And / or, processing the light intensity distribution evaluation diagram to obtain light intensities at different angles; calculating the sum of the light intensities at all angles within a preset angle range to obtain the local light intensity sum; calculating the ratio of the local light intensity sum to the total light intensity of the light emitted by the Micro-LED array to be tested to obtain the luminous intensity ratio.

7. The Micro-LED array measurement method based on phase reconstruction according to claim 1, characterized in that: The measurement system further includes a focusing lens device, a microscope objective lens, and an image sensor. Before performing phase reconstruction on the focus plane image and the multiple out-of-focus plane images, the method further includes: Calibrate the focusing lens device, the microscope objective lens, and the image sensor; Establishing an error correction model based on the calibrated focusing lens device, the microscope objective lens, and the image sensor; wherein the error correction model is used to correct aberrations introduced by the focusing lens device, the microscope objective lens, and the image sensor; Acquire a focus plane image to be corrected and a plurality of defocus plane images to be corrected of the Micro-LED array to be tested sent by the image sensor; The error correction model is used to correct the focus surface image to be corrected and each of the defocus surface images to be corrected, so as to obtain the corresponding focus surface image and the multiple defocus surface images.

8. The Micro-LED array measurement method based on phase reconstruction according to claim 1, characterized in that: The measurement system further includes a focusing lens device, and the method further includes: Acquire initial surface polynomial parameters of the focusing lens component and initial model parameters of the phase reconstruction model; wherein the initial surface polynomial parameters are initial values of the surface polynomial parameters of the focusing lens component, and the initial model parameters are initial values of the model parameters of the phase reconstruction model; Simulating and generating a plurality of defocused surface light intensity signal images under the initial surface polynomial parameters, and performing phase reconstruction on the plurality of defocused surface light intensity signal images based on the initial model parameters using the phase reconstruction model to obtain reconstructed phase distribution data; Constructing a loss function based on the reconstructed phase distribution data and the ideal phase distribution data at the corresponding position, jointly optimizing the surface polynomial parameters of the focusing lens device and the model parameters of the phase reconstruction model through a back propagation algorithm, iteratively optimizing until the loss function converges, and obtaining optimized surface polynomial parameters and optimized model parameters; The optimized surface polynomial parameters are used as actual working parameters of the focusing lens component, and the optimized model parameters are used as final model parameters of the phase reconstruction model.

9. The Micro-LED array measurement method based on phase reconstruction according to claim 8, characterized in that: The calculation formula of the loss function is as follows: Where RMSE represents the root mean square error, M represents the total number of pixels in the vertical direction of the defocused light intensity signal image, N represents the total number of pixels in the horizontal direction of the defocused light intensity signal image, φ(i,j) represents the reconstructed phase value at the pixel position (i,j), and φ0(i,j) represents the ideal phase value at the pixel position (i,j).

10. A measurement system, characterized in that: The measurement system includes a computer configured to implement the phase reconstruction-based Micro-LED array measurement method according to any one of claims 1 to 9; the measurement system further includes: a first displacement platform configured to move the Micro-LED array to be measured in the x-axis direction and the y-axis direction; a stage, disposed on the first displacement platform, for carrying and adjusting the pitch angle of the light-emitting surface of the Micro-LED array to be measured so that the light-emitting surface of the Micro-LED array is perpendicular to the optical axis of the measurement system; A focusing lens device is provided on the outgoing light path of the Micro-LED array to be tested, and is used to separate and converge the crosstalk of light beams generated by adjacent light-emitting units in the Micro-LED array to be tested; A microscope objective lens is provided on the outgoing light path of the focusing lens device and is used to amplify the light beam converged by the focusing lens device; an image sensor, disposed on an outgoing light path of the microscope objective lens and mechanically connected to the microscope objective lens, for receiving and recording light intensity information magnified by the microscope objective lens to obtain the in-focus plane image and the multiple out-of-focus plane images; The second displacement platform is used to adjust the height of the microscope objective lens and the image sensor in the z-axis direction. The second displacement platform is connected to both sides of the image sensor through an adapter plate.

11. The measuring system according to claim 10, characterized in that The accuracy of the first displacement platform reaches ±10 μm, the travel of the first displacement platform is greater than the size of the Micro-LED array to be measured, and the aperture of the focusing lens device is more than three times the size of the Micro-LED array to be measured; the accuracy of the second displacement platform reaches ±1 μm, and the travel of the second displacement platform is greater than three times the focal depth of the microscope objective lens; And / or, the numerical aperture of the microscope objective lens is greater than the numerical aperture of the focusing lens component.

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