An optical performance detection method based on phase deflectometry, medium and device

Abstract

The present application relates to the technical field of precision visual measurement, and particularly relates to an optical performance detection method based on phase deflectometry, a medium and equipment. The method comprises the following steps: obtaining actual point cloud data P of a target surface of a measured object based on reflective phase deflectometry. Design point cloud data Q of the target surface of the measured object is obtained. According to Q and P, a rotation transformation coefficient R * and a translation transformation coefficient T * are determined. According to P, R * and T * , initial measured point cloud data Q' is generated. Target surface shape data of the measured object is generated according to position coordinates of a plurality of points contained in Q'. The target surface shape data of the measured object is subjected to optical performance detection, and optical performance data of the target surface of the measured object is generated. The present application can directly measure and evaluate the optical performance of a measured part more comprehensively and accurately, and gets rid of the non-intuitiveness of the prior art which only evaluates surface shape error, slope error and curvature error of the measured part.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision visual measurement, in particular to an optical performance detection method based on phase deflectometry, a medium and equipment. BACKGROUND

[0002] Phase deflectometry, also known as reflective phase measurement deflectometry, is a visual measurement method capable of non-contact surface measurement of surface error, slope error and curvature error of reflective optical surfaces in a large dynamic range without the need for compensation mirrors. However, after measuring the optical surface to be measured, whether it is surface error analysis or slope error and curvature error analysis, the ultimate goal is to identify whether the optical surface under the current production state can meet the system requirements of optical performance design indicators such as aberration, distortion and resolution when used in an optical system.

[0003] In the prior art, transmission phase deflectometry can only be used to measure and evaluate the surface error, slope error and curvature error of the measured part, which is relatively single. Moreover, the topographic data of the measured part surface cannot be obtained. Therefore, it is impossible to realize a more comprehensive measurement and evaluation method of the optical performance of the measured part in reflective phase deflectometry. SUMMARY

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] According to one aspect of the present application, an optical performance detection method based on phase deflectometry is provided, which comprises the following steps:

[0006] Obtaining actual point cloud data P of the target surface of the object to be measured based on reflective phase deflectometry.

[0007] Obtaining design point cloud data Q of the target surface of the object to be measured.

[0008] Determining rotation conversion coefficient R * and translation conversion coefficient T * according to Q and P. Wherein, R * and T * satisfy the following conditions:

[0009] R * , T * = min|| (R i P + T i ) · - Q ||

[0010] Wherein, min||·|| is the minimum value function of the two norms. R i and T i are the rotation conversion coefficient and the translation conversion coefficient at the i-th iteration, respectively.

[0011] According to P, R * and T * , an initial to-be-measured point cloud data Q' is generated. Q' satisfies the following conditions:

[0012] Q' = R * P + T *

[0013] According to the position coordinates of the plurality of points contained in Q', target to-be-measured surface shape data is generated.

[0014] Optical performance detection is performed on the target to-be-measured surface shape data, and optical performance data of the target surface of the to-be-measured object is generated.

[0015] According to a second aspect of the present application, a non-transitory computer readable storage medium is provided, the non-transitory computer readable storage medium storing a computer program, the computer program being executed by a processor to implement the above-mentioned optical performance detection method based on phase deflectometry.

[0016] According to a third aspect of the present application, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the computer program to implement the above-mentioned optical performance detection method based on phase deflectometry.

[0017] The present application has at least the following beneficial effects:

[0018] In the present application, the measured part obtains measurement point cloud in the measurement coordinate system through reflective phase deflectometry, and the measurement point cloud of the measured part is compared with the target surface shape data designed thereby to obtain the corresponding coordinate conversion matrix, i.e., the rotation conversion coefficient R * and the translation conversion coefficient T * . Further, the coordinate system corresponding to the measurement result can be converted to the design coordinate system in which the optical design file is located, and the actual surface shape data of the to-be-measured object is generated, and finally the optical performance of the measured part corresponding to the optical system under the actual measured surface shape is measured and analyzed using the optical design software. Thus, the present application can directly measure and evaluate the optical performance of the measured part more comprehensively and accurately, and get rid of the non-intuitive evaluation of the surface shape error, slope error, and curvature error of the measured part in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0020] Figure 1 A flowchart of an optical performance detection method based on phase deflectometry is provided for an embodiment of the present application.

[0021] Figure 2 For an embodiment of the present application, under the HUD (head-up display) surface shape measurement result, the optical system is simulated for imaging quality.

[0022] Figure 3 For an embodiment of the present application, under the HUD surface shape measurement result, the optical system is analyzed for a point array diagram. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] As a possible embodiment of the present application, as shown in Figure 1 An optical performance detection method based on phase deflectometry is provided, which comprises the following steps:

[0025] S100: Obtain actual point cloud data P of the target surface of the object to be measured based on reflective phase deflectometry.

[0026] Preferably, the reflective phase deflectometry includes any one of single-camera single-screen phase deflectometry, multi-camera single-screen phase deflectometry, single-camera multi-screen phase deflectometry, and multi-camera multi-screen phase deflectometry.

[0027] Further, the object to be measured includes any one of a metal mirror, a coated mirror, a glass blank before coating of the coated mirror, a resin lens, and a glass lens.

[0028] Specifically, a small-FOV multi-view phase deflectometry measurement device disclosed in CN202111649940 can be used to measure the surface shape of the free-form mirror in the vehicle-mounted head-up display optical system. The measured three-dimensional point cloud surface shape data is defined as P, and the corresponding design point cloud data is defined as Q.

[0029] Of course, other ways based on reflective phase deflectometry to measure the surface of an object can also be used in this step to obtain the point cloud data of the object to be measured.

[0030] S200: Obtain the design point cloud data Q of the target surface of the object to be measured.

[0031] S300: Determine the rotation transformation coefficient R * and the translation transformation coefficient T * according to Q and P. Wherein, R * and T * satisfy the following conditions:

[0032] R * , T * = min||(R i P+T i )-Q||

[0033] Wherein, min||·|| is the minimum value function of the two norms. R i and T i are the rotation transformation coefficient and the translation transformation coefficient at the i-th iteration, respectively.

[0034] Further, S301: Based on any one of the optimization algorithms in the least square method, the gradient descent method, the principal component analysis method and the iterative closest point method, the comparison processing is performed on Q and P to generate the rotation transformation coefficient R * and the translation transformation coefficient T * .

[0035] Specifically, in this step, the iterative closest point method is used to optimize the minimum difference between the corresponding points in P and Q. Further, the rotation matrix and the translation vector required for converting the measurement coordinate system in which the measurement point cloud is located to the design coordinate system in which the design surface point cloud is located, i.e. R * and T * , can be obtained.

[0036] After obtaining the corresponding R * and T * , P can be converted into data represented in the design coordinate system. That is, the actual surface data of the object to be measured is converted into a data form which is more convenient for the use of related detection software, and then the performance detection using the corresponding software can be more convenient.

[0037] Further, S302: The comparison processing is performed on Q and P, including:

[0038] S303: The data of the optical surface part in Q and P is compared and processed. And / or

[0039] S304: The data of the positioning structure part in Q and P is compared and processed.

[0040] Specifically, the optical surface can be a surface in the object to be measured that is only used for imaging. The positioning structure can be a structure in the object to be measured that is used for positioning assembly, such as a positioning column or a positioning surface.

[0041] Generally, if only the optical surface is evaluated, a comparison process can be performed on the data of the optical surface part in Q and P, and the result is obtained immediately. That is, a rigid transformation matrix between the measurement result and the optical design is found by taking the error two-norm of the point set as the objective function. The rigid transformation matrix obtained in this way can eliminate the surface form error formed in the processing process and is more suitable for the evaluation scenario of only the optical surface.

[0042] However, generally, the optical surface is finally assembled in the corresponding structure, and thus a certain assembly error is also generated. For example, in the assembly of an actual optical system, the HUD lens cannot be adjusted arbitrarily. The HUD mirror is positioned by the peripheral positioning structure. In this case, the actual surface form itself includes the processing error of the surface form and the positioning error of the surface form. Therefore, the comparison process is performed on the optical surface and the positioning structure at the same time, so that the surface form error and the positioning error can be eliminated, and the result is more accurate.

[0043] S400: generating initial point cloud data Q' according to P, R * , and T * . Q' satisfies the following conditions:

[0044] Q' = R*P + T *

[0045] S500: generating target surface form data of the object to be measured according to the position coordinates of the plurality of points included in Q'.

[0046] The measurement result is only a point cloud, and after the above steps, the measurement result can be transformed into the design coordinate system, and the actual surface form data of the object to be measured is generated. That is, the data can be represented in a mathematical manner of z = f(x, y) or f(x, y, z) = 0, so as to be used for more rapid and efficient measurement by using the corresponding software in the later stage. In this step, an existing fitting algorithm can be used to generate the target surface form data. For example, an XY extended polynomial, Zernike, B-spline surface, etc. can be used as the fitting algorithm for generating the target surface form data.

[0047] S600: performing optical performance detection on the target surface form data to generate optical performance data of the target surface form of the object to be measured.

[0048] The optical performance of the optical system includes performance evaluation data such as distortion, ghosting, ghosting, uniformity, resolution, modulation transfer function, and aberration.

[0049] In the present application, the measured part obtains the measurement point cloud in the measurement coordinate system through the reflective phase deflectometry, compares the measurement point cloud of the measured part with the target surface shape data of the design, to obtain the corresponding coordinate conversion matrix, i.e. the rotation conversion coefficient R * and the translation conversion coefficient T * . Further, the measurement result corresponding coordinate system can be converted to the design coordinate system of the optical design file, and the actual surface shape data of the measured object is generated, and finally the optical performance of the measured part under the actual measured surface shape corresponding to the optical system is measured and analyzed by using the optical design software. Thus, the present application can directly measure and evaluate the optical performance of the measured part more comprehensively and accurately, and get rid of the non-intuitive evaluation of the surface shape error, slope error and curvature error of the measured part in the prior art.

[0050] As another possible embodiment of the present application, S500: generating target measured surface shape data according to the position coordinates of the plurality of points contained in Q', including:

[0051] S501: generating XY extended polynomial surface data according to the position coordinates of the plurality of points contained in Q' and the fitting algorithm.

[0052] The fitting algorithm satisfies the following conditions:

[0053]

[0054] Wherein, c is the curvature. k is the quadratic curve coefficient. r 2 = x 2 +y 2 . The polynomial term E i (x,y) is only the power series in x and y directions. The first term is x, then y, followed by x*x, x*y, y*y, etc. There are 2 terms for 1st order, 3 terms for 2nd order, 4 terms for 3rd order, etc. Ai is the coefficient of the i-th extended polynomial. N is the number of polynomial terms, and the extended polynomial surface with 8 polynomial terms can be selected for fitting the measurement result in the present embodiment.

[0055] Further, S600: optical performance detection on the target measured surface shape data, to generate the optical performance data of the target surface shape of the measured object, including:

[0056] S601: inputting the XY extended polynomial surface data into the Zemax detection software, to generate the optical performance data of the target surface shape of the measured object.

[0057] The position coordinates of the plurality of points included in the measurement point cloud Q' in the design file coordinate system are fitted according to the fitting algorithm to obtain the parameters of the extended polynomial, and an 8-term XY extended polynomial surface is generated to obtain the surface shape data of the actual surface shape of the object in the design coordinate system. In the optical design software Zemax, the fitted 8-term XY extended polynomial surface is imported and replaces the design surface shape data of the free-form mirror. Finally, the optical design software Zemax is used to measure and analyze the imaging quality, point spread function, and other optical performance indicators of the current optical system. Figure 2 and Figure 3

[0058] As another possible embodiment of the present application, S500: generating target surface shape data according to the position coordinates of the plurality of points included in Q', including:

[0059] S501: interpolating the target blank area according to the position coordinates of the plurality of points included in Q' and the interpolation algorithm to generate the target surface shape data.

[0060] Specifically, the plurality of target blank areas included in Q' are also missing corresponding points in the region. If they are not completed, it will cause a larger error at this position when generating the corresponding surface shape or performing optical performance detection, thereby affecting the accuracy of the final measurement result. Therefore, the data can be processed by this embodiment to improve the accuracy of the measurement result.

[0061] The embodiment of the present application also provides a non-transitory computer readable storage medium, which can be arranged in an electronic device to save at least one instruction or at least one program related to a method in the method embodiment, and the at least one instruction or the at least one program is loaded and executed by the processor to realize the method provided by the above-mentioned embodiment.

[0062] The embodiment of the present application also provides an electronic device, which includes a processor and the aforementioned non-transitory computer readable storage medium.

[0063] The embodiment of the present application also provides a computer program product, which includes program code, and when the program product is running on an electronic device, the program code is used to make the electronic device execute the steps in the method according to various exemplary embodiments of the present application described in the specification.

[0064] ​Moreover, although individual steps of the methods in the present disclosure are described in a particular order in the figures, this is not required or implied as to the order of execution of the steps, nor is it required that all of the steps be performed to achieve the desired result. Additionally or alternatively, certain steps can be omitted, multiple steps can be combined into a single step, a single step can be broken into multiple steps, etc.

[0065] Through the description of the above embodiments, those skilled in the art can easily understand that the example embodiments described herein can be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solutions according to the embodiments of the present disclosure can be embodied in the form of a software product. The software product can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash disk, a mobile hard disk, etc.) or a network, and includes a number of instructions to make a computing device (which can be a personal computer, a server, a mobile terminal, or a network device, etc.) execute the methods according to the embodiments of the present disclosure.

[0066] In the example embodiments of the present disclosure, an electronic device capable of implementing the above method is also provided.

[0067] Those skilled in the art can understand that each aspect of the present disclosure can be implemented as a system, a method or a program product. Therefore, each aspect of the present disclosure can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, microcode, etc.), or an embodiment combining hardware and software aspects, which can be generally referred to as a "circuit", a "module" or a "system".

[0068] The electronic device according to this embodiment of the present disclosure. The electronic device is merely an example, and should not bring any limitation to the functions and use range of the embodiments of the present disclosure.

[0069] The electronic device is in the form of a general computing device. The components of the electronic device can include, but are not limited to, the above-mentioned at least one processor, the above-mentioned at least one storage, and a bus connecting different system components (including storage and processor).

[0070] The storage stores program codes which can be executed by the processor, so that the processor executes the steps according to various example embodiments of the present disclosure described in the above "example method" section of the present specification.

[0071] The storage can include a readable medium in the form of a volatile storage, such as a random access memory (RAM) and / or a cache memory, and can further include a read-only memory (ROM).

[0072] The storage can also include a program / utility, having a set (at least one) of program modules that are configured to carry out the functions of the examples described herein, including an operating system, one or more application programs, other program modules, and program data, each or some combination thereof, likely including implementation of a networking environment.

[0073] The bus can represent one or more of several types of bus structures, including a storage bus or

[0074] The electronic device can also communicate with one or more external devices such as a keyboard or a pointing device, through an I / O interface. Additionally, the electronic device can communicate with one or more devices that enable a user to interact with the electronic device through an input device or devices 110. In the example of the electronic device being a network server, the input device or devices 110 can include a keyboard, pointing device, microphone, etc. The input device or devices 110 can be used to receive input data for use by or concerning the electronic device. The electronic device can also communicate with one or more devices that enable a user to interact with the electronic device through an output device or devices 112. In the example of the electronic device being a network server, the output device or devices 112 can include a display, a speaker, etc. The output device or devices 112 can be used to provide output data to a user of the electronic device. The electronic device can also include communication interface 114 enabling wired or wireless communication with one or more other devices.

[0075] Those skilled in the art will readily understand that the example embodiments described herein can be implemented by software and / or by hardware coupled with software, as described above. Thus, the technical solutions according to the embodiments of the present disclosure can be embodied in the form of a software product. The software product can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash disk, a mobile hard disk, etc.) or a network, and includes a number of instructions to enable a computing device (which can be a personal computer, a server, a terminal device, or a network device, etc.) to perform the methods according to the embodiments of the present disclosure.

[0076] In the example embodiments of the present disclosure, a computer readable storage medium is also provided, which stores a program product capable of implementing the method described above. In some possible embodiments, various aspects of the present disclosure can also be implemented in the form of a program product, which includes program codes for causing a terminal device to perform the steps described in the “example method” section of the present disclosure according to various example embodiments of the present disclosure when the program product is run on the terminal device.

[0077] The program product can employ any combination of one or more computer-readable media. The computer-readable media can be a computer-readable storage medium or a computer-readable signal medium. The computer-readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0078] The computer-readable signal medium can include a computer-readable storage medium that is communicated, propagated, or transported, for example, over a communication link, a wireless link, or a hard-wired link. The computer-readable signal medium can also be a computer-readable storage medium that is embodied into a computer-readable storage medium or used to manufacture a computer-readable storage medium. The computer-readable storage medium can be any appropriate medium (including the one or more computer-readable media described above) that participates in providing instructions to an instruction execution system, apparatus, or device such that the instructions, which properly render the instruction-execution system, apparatus, or device into a

[0079] The program code embodied on the computer-readable media can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0080] The program code can be executed by one or more programmable processors, which can be individual or grouped processors, to perform the methods described above and illustrated in the flow charts. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). These network connections are

[0081] In addition, the above-described flowcharts are merely illustrative of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to limit the purpose. It is easily understood that the processes shown in the above-described flowcharts do not indicate or limit the time sequence of the processes. In addition, it is easily understood that the processes can be executed synchronously or asynchronously, for example, in a plurality of modules.

[0082] It should be noted that, although several modules or units of the devices for action execution are mentioned in the above detailed description, the division into such modules or units is not mandatory. Indeed, according to an embodiment of the present disclosure, the features and functionalities of two or more of the above-described modules or units can be embodied in one module or unit. Conversely, the features and functionalities of one of the above-described modules or units can be further divided into several modules or units.

[0083] The above merely shows the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for detecting optical properties based on phase deflectometry, characterized in that, The method comprises the following steps: Obtaining actual point cloud data P of a target surface of an object to be measured based on reflective phase deflectometry; Obtaining design point cloud data Q of the target surface of the object to be measured; determining a rotation transformation coefficient R * and a translation transformation coefficient T * ; wherein R * and T * satisfy the following conditions: ； wherein, is a minimum function of the two norms; R i and T i are the rotation and translation transformation coefficients at the i-th iteration; R * and T * to convert the coordinate system corresponding to the measurement results into the design coordinate system in which the optical design file is located, and generate the surface shape data of the actual object to be measured; According to P, R * and T * , generate initial test point cloud data Q'; Q' satisfies the following conditions: ; Generating target surface data of the object to be measured according to position coordinates of a plurality of points contained in Q'; Performing optical performance detection on the target surface data of the object to be measured to generate optical performance data of the target surface of the object to be measured, the optical performance including distortion, ghosting, ghost image, uniformity, resolution, modulation transfer function and aberration; Based on any one optimization algorithm of least square method, gradient descent method, principal component analysis method and iterative nearest point method, Q and P are compared and processed to generate rotation conversion coefficient R * and translation conversion coefficient T * ; optical surface and positioning structure are used for comparison and processing at the same time to reduce surface error and positioning error; Performing comparison processing on Q and P, including: Performing comparison processing on data of an optical surface part in Q and P; and Performing comparison processing on data of a positioning structure part in Q and P; Performing optical performance detection on the target surface data of the object to be measured to generate optical performance data of the target surface of the object to be measured, including: Inputting XY extended polynomial curved surface data into Zemax detection software to generate optical performance data of the target surface of the object to be measured.

2. The method of claim 1, wherein, Generating target surface data of the object to be measured according to position coordinates of a plurality of points contained in Q', including: Generating XY extended polynomial curved surface data according to position coordinates of a plurality of points contained in Q' and a fitting algorithm; The fitting algorithm satisfies the following condition: ； where A i is the coefficient of the ith extended polynomial.

3. The method of claim 1, wherein, Generating target surface data of the object to be measured according to position coordinates of a plurality of points contained in Q', including: Generating target surface data of the object to be measured by interpolating a target blank area according to position coordinates of a plurality of points contained in Q' and an interpolation algorithm.

4. The method of claim 1, wherein, The reflective phase deflectometry includes any one of single-camera single-screen phase deflectometry, multi-camera single-screen phase deflectometry, single-camera multi-screen phase deflectometry and multi-camera multi-screen phase deflectometry.

5. The method of claim 1, wherein, The object to be measured includes any one of a metal mirror, a coated mirror, an injection molded blank before coating of the coated mirror, a glass blank before coating of the coated mirror, a resin lens and a glass lens. 6.A non-transitory computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a processor, cause the processor to perform the method of any one of claims 1 to 5. The computer program, when executed by a processor, implements the optical performance detection method based on phase deflectometry according to any one of claims 1 to 5.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor, when executing the computer program, implements the optical performance detection method based on phase deflectometry according to any one of claims 1 to 5.

Images