Structural illumination measurement system and method based on binary fringe modulation degree

Abstract

The invention discloses a structural illumination measurement system and method based on a binary fringe modulation degree. The system comprises a displacement table; the projection device is used for projecting two complementary binary stripe images; the imaging device is used for acquiring a fringe image reflected by the measured object; the coaxial light path device is used for irradiating the two complementary binary fringe images projected by the projection device to the measured object on the displacement table and reflecting the fringe image reflected by the measured object on the displacement table to the imaging device; the image processing unit is used for receiving the stripe image acquired by the imaging device and processing the stripe image into a modulation degree image; drawing a modulation degree-scanning position response curve according to a pixel gray value in the modulation degree image; and obtaining the relative height of the pixel, and measuring the three-dimensional shape information of the surface of the measured object according to the relative height of the pixel. According to the invention, the problem of low efficiency of a traditional structure illumination measurement technology can be solved, and high-efficiency measurement based on structure illumination is realized.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement technology, and in particular to a structured illumination measurement system and method based on binary fringe modulation. Background Art

[0002] Structured illumination measurement technology is an optical measurement technology. It uses a projection device to project multiple fringe images, uses phase shift technology to solve the modulation image of the object surface, and combines axial scanning to locate the best focus position of each object point, thereby realizing the surface morphology measurement of micro-nano scale objects. Structured illumination measurement technology shows good measurement capabilities in the measurement of rough surfaces, and has gradually become one of the research directions that have attracted much attention in the field of three-dimensional surface morphology measurement.

[0003] However, the low measurement efficiency limits the application of structured illumination measurement technology in actual industrial scenarios. For example, structured illumination measurement requires a large amount of data, which means that data collection and processing are very time-consuming processes. In response to this problem, researchers have conducted many studies on improving the measurement speed. There are two mainstream ideas: one is to use less image information, and the other is to avoid axial scanning. The first method uses two phase-shifted images to obtain a differential image, and combines the Hilbert transform to solve the modulation. However, due to sampling problems, the Hilbert transform method usually cannot perfectly remove the stripes in the captured image, so there will be problems with details in the subsequent reconstruction results. The second method is to use two cameras to collect focused and defocused images respectively, obtain the differential modulation curve, and avoid long-term axial scanning during the measurement process. However, this method increases the cost due to the addition of additional cameras, and at the same time puts higher requirements on system construction and algorithm implementation. Summary of the invention

[0004] The embodiments of the present invention provide a structured illumination measurement system and method based on binary fringe modulation, aiming to solve the problem of low efficiency of traditional structured illumination measurement technology and realize efficient measurement based on structured illumination.

[0005] The embodiment of the present invention provides a structured illumination measurement system based on binary fringe modulation, comprising:

[0006] The translation stage is used to fix the object to be measured and can drive the object to be measured to move;

[0007] A projection device, used for projecting two complementary binary fringe images;

[0008] An imaging device, used for collecting a fringe image after being reflected by the measured object;

[0009] A coaxial optical path device, arranged between the projection device and the displacement stage, and between the displacement stage and the imaging device, for irradiating the two complementary binary fringe images projected by the projection device onto the object to be measured on the displacement stage, and reflecting the fringe image reflected by the object to be measured on the displacement stage to the imaging device;

[0010] An image processing unit, connected to the imaging device, is used to:

[0011] Receiving a fringe image acquired by the imaging device, and processing the fringe image into a modulation image;

[0012] Draw a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image;

[0013] The pixel relative height is acquired based on the modulation degree-scanning position response curve, and the three-dimensional surface morphology information of the measured object is obtained according to the pixel relative height measurement.

[0014] Furthermore, the coaxial optical path device is a microscopic optical path device, and the microscopic optical path device includes:

[0015] A first beam splitter, disposed between the projection device and the displacement stage, and between the displacement stage and the imaging device;

[0016] A first tube lens is disposed between the projection device and the first beam splitter, and a focal plane of the first tube lens is close to the projection device;

[0017] A second tube lens is disposed between the imaging device and the first beam splitter, and a focal plane of the second tube lens is close to the imaging device;

[0018] The objective lens is arranged between the first beam splitter and the translation stage.

[0019] Furthermore, the coaxial optical path device is a telecentric optical path device, and the telecentric optical path device includes:

[0020] A second beam splitter, disposed between the projection device and the displacement stage, and between the displacement stage and the imaging device;

[0021] A first telecentric lens, disposed between the projection device and the second beam splitter;

[0022] The second telecentric lens is arranged between the imaging device and the second beam splitter.

[0023] An embodiment of the present invention further provides a structured illumination measurement method based on binary fringe modulation, which is applied to the structured illumination measurement system based on binary fringe modulation as described in any one of the above items, and the method includes:

[0024] Projecting two complementary binary fringe images through a projection device;

[0025] The two complementary binary fringe images projected by the projection device are irradiated onto the measured object on the displacement stage through a coaxial optical path device, and the fringe images reflected by the measured object on the displacement stage are reflected to an imaging device;

[0026] The reflected fringe image is collected by the imaging device, and the object to be measured is driven to move to a next position by the translation stage according to a preset motion strategy, and the fringe image is continuously collected until the preset motion strategy is executed;

[0027] Receiving the fringe image collected by the imaging device through an image processing unit, and processing the fringe image into a modulation degree image;

[0028] Draw a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image;

[0029] The pixel relative height is acquired based on the modulation degree-scanning position response curve, and the three-dimensional surface morphology information of the measured object is obtained according to the pixel relative height measurement.

[0030] Furthermore, the expression of the complementary binary fringe image is:

[0031]

[0032] in, Represents two complementary binary fringe images, x and y represent the horizontal and vertical coordinates of the image pixels respectively, a(x, y) represents the background intensity of the complementary binary fringe image, b(x, y) represents the modulation image of the complementary binary fringe image, and sgn[sin(2πν0x)] represents the square wave function with a frequency of ν0.

[0033] Furthermore, the expression of the fringe image is:

[0034]

[0035] in, represents the fringe images corresponding to the two complementary binary fringe images, A(x, y) represents the background intensity of the fringe image, and B(x, y) represents the modulation image of the fringe image.

[0036] Furthermore, the receiving of the fringe image acquired by the imaging device and processing the fringe image into a modulation image includes:

[0037] Based on the expression of the fringe image, the fringe images corresponding to the two complementary binary fringe images are processed by differential operation to eliminate the background intensity term and the square wave function term therein;

[0038] According to the following formula, the fringe images corresponding to the two complementary binary fringe images are subjected to difference processing to obtain the modulation degree image of the fringe image:

[0039]

[0040] Wherein, B(x,y) represents the modulation image of the fringe image, and Respectively represent one of the fringe images.

[0041] Furthermore, the step of drawing a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image includes:

[0042] For each pixel position in the modulation image of the fringe image, collecting the corresponding pixel grayscale value;

[0043] Based on the pixel grayscale value, a modulation degree-scanning position response curve is plotted for each pixel position.

[0044] Furthermore, the step of obtaining the pixel relative height based on the modulation degree-scanning position response curve, and obtaining the surface three-dimensional topography information of the measured object according to the pixel relative height measurement, includes:

[0045] Selecting n data points in the peak region of the modulation index-scanning position response curve as fitting points;

[0046] Based on the fitting points, a Gaussian fitting algorithm is used to fit the modulation degree-scanning position response curve to obtain a fitting curve;

[0047] Obtaining a fitting coefficient of the fitting curve, and determining a scanning position corresponding to the peak area according to the fitting coefficient, and then using the scanning position as a relative height of a corresponding pixel position;

[0048] The relative heights of all pixel positions are summarized, and the three-dimensional surface morphology information of the measured object is obtained based on the relative height measurements of all pixel positions.

[0049] Furthermore, the Gaussian fitting algorithm is a least squares Gaussian fitting algorithm.

[0050] The embodiments of the present invention provide a structured illumination measurement system and method based on binary fringe modulation. Complementary binary fringes are used to solve the modulation. This not only reduces the number of acquired images, but also simplifies the modulation solution process. That is, both data acquisition efficiency and image processing efficiency are improved, thereby achieving efficient structured illumination measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0052] Figure 1 A schematic diagram of the structure of a structured illumination measurement system based on binary fringe modulation provided by an embodiment of the present invention;

[0053] Figure 2 Another schematic diagram of the structure of a structured illumination measurement system based on binary fringe modulation provided by an embodiment of the present invention;

[0054] Figure 3 An example graph of a curve in a structured illumination measurement system based on binary fringe modulation provided by an embodiment of the present invention;

[0055] Figure 4 A schematic flow chart of a structured illumination measurement method based on binary fringe modulation provided by an embodiment of the present invention;

[0056] Figure 5 A schematic diagram of a sub-process of a structured illumination measurement method based on binary fringe modulation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0058] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0059] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0060] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0061] See below Figure 1 The embodiment of the present invention provides a structured illumination measurement system based on binary fringe modulation, comprising:

[0062] The translation stage 10 is used to fix the object 101 to be measured and to drive the object 101 to be measured to move;

[0063] A projection device 20, for projecting two complementary binary fringe images;

[0064] An imaging device 30, used for collecting a fringe image reflected by the measured object 101;

[0065] A coaxial optical path device, disposed between the projection device 20 and the translation stage 10, and between the translation stage 10 and the imaging device 30, for irradiating the two complementary binary fringe images projected by the projection device 20 onto the object to be measured 101 on the translation stage 10, and reflecting the fringe image reflected by the object to be measured 101 on the translation stage 10 to the imaging device 30;

[0066] The image processing unit 50 is connected to the imaging device 30 and is used for:

[0067] Receiving the fringe image acquired by the imaging device 30, and processing the fringe image into a modulation degree image;

[0068] Draw a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image;

[0069] The pixel relative height is acquired based on the modulation degree-scanning position response curve, and the three-dimensional surface morphology information of the measured object 101 is obtained according to the pixel relative height measurement.

[0070] In this embodiment, the structured illumination measurement system based on binary fringe modulation includes a displacement stage 10 (for example, a displacement stage 10 using a piezoelectric driver PZT), a projection device 20, an imaging device 30, a coaxial optical path device, and an image processing unit 50. When performing structured illumination measurement, the object 101 to be measured is first fixed on the displacement stage 10, and it is ensured that the object 101 to be measured will not be offset when the displacement stage 10 moves, and the object 101 to be measured is driven by the displacement stage 10 to move to a preset measurement position. Then, two complementary binary fringe images are projected by the projection device 20, and after passing through the coaxial optical path device, they are irradiated onto the surface of the object 101 to be measured, and at the same time, the coaxial optical path device transmits the fringe image reflected by the object 101 to the imaging device 30, and the imaging device 30 synchronously collects the fringe image modulated by the object morphology. Then, according to a preset motion strategy, for example, the displacement stage 10 is moved with a preset specific step length so that different positions of the object 101 to be measured are measured, until the preset motion strategy is executed, for example, the displacement stage 10 drives the object 101 to be measured to a specified position, thereby obtaining a plurality of fringe images. Thereafter, the multiple captured fringe images are processed by the image processing unit 50, and corresponding modulation images are obtained. Of course, in practical applications, after a fringe image is captured, the image processing unit 50 is used to obtain the corresponding modulation image, and then the displacement stage 10 is controlled to drive the object 101 to be measured to move to the next measurement position. For each modulation image, for each pixel position therein, the grayscale value of the pixel position in all modulation images is extracted, and a modulation-scanning position response curve is plotted, such as Figure 3 As shown, the relative height of the pixel is obtained according to the modulation degree-scanning position response curve, so as to obtain the three-dimensional surface morphology information of the object 101 to be measured based on the relative height measurement of all pixels.

[0071] This embodiment uses complementary binary fringes to solve the modulation degree, which not only reduces the number of collected images but also simplifies the modulation degree solving process, that is, both the data collection efficiency and the image processing efficiency are improved, thereby achieving efficient structured illumination measurement.

[0072] In a specific application scenario, the image processing unit 50 can be configured on a server or a service terminal, that is, it can be communicated with the imaging device 30 through the server or the service terminal to obtain the stripe image captured by the imaging device 30, and then subsequent image processing and structured illumination measurement can be implemented on the server or the service terminal.

[0073] In one embodiment, the coaxial optical path device is a microscopic optical path device 41, and the microscopic optical path device 41 includes:

[0074] A first beam splitter 411 is disposed between the projection device 20 and the displacement stage 10, and between the displacement stage 10 and the imaging device 30;

[0075] A first tube lens 412 is disposed between the projection device 20 and the first beam splitter 411, and a focal plane of the first tube lens 412 is close to the projection device 20;

[0076] A second tube lens 413 is disposed between the imaging device 30 and the first beam splitter 411, and a focal plane of the second tube lens 413 is close to the imaging device 30;

[0077] The objective lens 414 is disposed between the first beam splitter 411 and the translation stage 10 .

[0078] Combination Figure 1 , this embodiment adopts the microscopic optical path device 41 as the coaxial optical path device, that is, the structured illumination measurement system based on binary fringe modulation provided by this embodiment is suitable for three-dimensional measurement of the microscopic field of view. In practical applications, when the microscopic optical path device 41 is adopted as the coaxial optical path device, when the object to be measured 101 is initially driven to move to the preset measurement position by the displacement stage 10, the object to be measured 101 can be located near the far depth of field of the microscopic optical path device 41. During the image acquisition process, two complementary binary fringe images are projected by the projection device 20, which will pass through the first beam splitter 411, the first tube lens 412 and the objective lens 414, and then irradiate the surface of the object to be measured 101, and then be reflected to the imaging device 30 by the first beam splitter 411, the second tube lens 413 and the objective lens 414. When the object 101 is subsequently driven to move according to the predicted motion strategy by the translation stage 10, the designated position can be set as the depth of field position of the microscope optical path device 41, that is, the movement of the object 101 stops when the surface of the object 101 completely exceeds the depth of field.

[0079] In another embodiment, the coaxial optical path device is a telecentric optical path device 42, and the telecentric optical path device 42 includes:

[0080] A second beam splitter 421 is disposed between the projection device 20 and the displacement stage 10, and between the displacement stage 10 and the imaging device 30;

[0081] A first telecentric lens 422 is disposed between the projection device 20 and the second beam splitter 421;

[0082] The second telecentric lens 423 is disposed between the imaging device 30 and the second beam splitter 421 .

[0083] Combination Figure 2In this embodiment, when the telecentric optical path device 42 is used as the coaxial optical path device, the design of the telecentric lens ensures that the light passes within a specific angle, effectively reducing the measurement error caused by lens distortion. Among them, the first telecentric lens 422 is responsible for accurately projecting the two complementary binary fringe images generated by the projection device 20 onto the surface of the measured object 101, while the second telecentric lens 423 is responsible for capturing the reflected fringe image and guiding it to the imaging device 30.

[0084] It can be seen that the structured illumination measurement system based on binary fringe modulation provided in this embodiment is not only applicable to three-dimensional measurement of microscopic field of view, but also applicable to various other fields of view, such as telecentric field of view.

[0085] Figure 4 A schematic flow chart of a structured illumination measurement method based on binary fringe modulation provided in an embodiment of the present invention is applied to the structured illumination measurement system based on binary fringe modulation as described above. The method comprises steps S101 to S106.

[0086] Step S101, projecting two complementary binary fringe images through the projection device 20;

[0087] Step S102, irradiating the two complementary binary fringe images projected by the projection device 20 onto the object 101 to be measured on the translation stage 10 through a coaxial optical path device, and reflecting the fringe image reflected by the object 101 to be measured on the translation stage 10 to the imaging device 30;

[0088] Step S103, collecting the reflected fringe image through the imaging device 30, and driving the object 101 to move to the next position through the translation stage 10 according to the preset motion strategy, and continuing to collect the fringe image until the preset motion strategy is executed;

[0089] Step S104, receiving the fringe image acquired by the imaging device 30 through the image processing unit 50, and processing the fringe image into a modulation degree image;

[0090] Step S105, drawing a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image;

[0091] Step S106 , obtaining pixel relative height based on the modulation degree-scanning position response curve, and obtaining the three-dimensional surface morphology information of the measured object 101 according to the pixel relative height measurement.

[0092] In this embodiment, when performing structured illumination measurement based on binary fringe modulation, the object 101 to be measured is first fixed on the displacement stage 10, and it is ensured that the object 101 to be measured will not be offset when the displacement stage 10 moves, and the displacement stage 10 drives the object 101 to move to a preset measurement position. Then, two complementary binary fringe images are projected by the projection device 20, and after passing through the coaxial optical path device, they are irradiated onto the surface of the object 101 to be measured. At the same time, the coaxial optical path device also transmits the fringe image reflected by the object 101 to the imaging device 30, and the imaging device 30 synchronously collects the fringe image modulated by the object morphology. Then, according to the preset motion strategy, for example, the displacement stage 10 is moved with a preset specific step length so that different positions of the object 101 to be measured are measured, until the preset motion strategy is executed, for example, the displacement stage 10 drives the object 101 to move to a specified position, thereby obtaining multiple fringe images. Thereafter, the multiple fringe images collected are processed by the image processing unit 50, and corresponding modulation images are obtained. Of course, in practical applications, after acquiring a fringe image, the image processing unit 50 may be used to obtain a corresponding modulation image, and then the translation stage 10 may be controlled to drive the object 101 to move to the next measurement position. For each modulation image, for each pixel position therein, the grayscale value of the pixel position in all modulation images is extracted, and a modulation-scanning position response curve is plotted, and then the relative height of the pixel is obtained according to the modulation-scanning position response curve, so as to obtain the surface three-dimensional morphology information of the object 101 to be measured based on the relative height measurement of all pixels.

[0093] This embodiment uses complementary binary fringes to solve the modulation degree, which not only reduces the number of collected images but also simplifies the modulation degree solving process, that is, both the data collection efficiency and the image processing efficiency are improved, thereby achieving efficient structured illumination measurement.

[0094] In a specific embodiment, the expression of the complementary binary fringe image is:

[0095]

[0096] in, Represents two complementary binary fringe images, x and y represent the horizontal and vertical coordinates of the image pixels, respectively, a ( x,y ) represents the background intensity of the complementary binary fringe image, b ( x,y ) It represents the modulation image of the complementary binary fringe image, and sgn[sin(2πν0x)] represents the square wave function with frequency ν0.

[0097] In addition, the expression of the fringe image is:

[0098]

[0099] in, represents the fringe images corresponding to the two complementary binary fringe images, A(x, y) represents the background intensity of the fringe image, and B(x, y) represents the modulation image of the fringe image.

[0100] Furthermore, the receiving of the fringe image acquired by the imaging device 30 and processing the fringe image into a modulation image includes:

[0101] Based on the expression of the fringe image, the fringe images corresponding to the two complementary binary fringe images are processed by differential operation to eliminate the background intensity term and the square wave function term therein;

[0102] According to the following formula, the fringe images corresponding to the two complementary binary fringe images are subjected to difference processing to obtain the modulation degree image of the fringe image:

[0103]

[0104] Wherein, B(x,y) represents the modulation image of the fringe image, and Respectively represent one of the fringe images.

[0105] In this embodiment, the two complementary binary fringe images projected by the projection device 20 are irradiated onto the surface of the object 101 after passing through the coaxial optical path device, and the imaging device 30 can also synchronously collect the fringe images reflected by the object 101 through the coaxial optical path device, and then the image processing unit 50 processes them to obtain the modulation degree image. Among them, the complementary binary fringe images can be as follows Figure 1 As shown in the red dotted box at the projection device 20 in FIG. 1 , it can be expressed as:

[0106]

[0107] Here, Represents a complementary binary stripe image, which contains and Here, when When the “±” in the formula is replaced by “+”, When , the “±” in the formula is replaced by “-”, which represents two complementary binary fringe images.

[0108] and Figure 1 The red dotted box in the lower right corner of FIG. 3 is the fringe image collected by the imaging device 30, which can be expressed as:

[0109]

[0110] Here, represents two fringe images captured by the imaging device 30, which include and Here, when When the “±” in the formula is replaced by “+”, When , “±” in the formula is replaced by “-”, which represents the fringe images captured by the two imaging devices 30.

[0111] Furthermore, according to the above formula, the background intensity term and the square wave function term in the formula can be eliminated by differential operation, and then the modulation image expression of the complementary binary fringe image can be obtained:

[0112]

[0113] As can be seen from the above, the fringe images captured by the two imaging devices 30 are After making the difference and taking the absolute value, the modulation image B(x,y) can be obtained.

[0114] In one embodiment, the step of drawing a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image comprises:

[0115] For each pixel position in the modulation image of the fringe image, collecting the corresponding pixel grayscale value;

[0116] Based on the pixel grayscale value, a modulation degree-scanning position response curve is plotted for each pixel position.

[0117] In this embodiment, after the modulation image is obtained, for each pixel position in each modulation image, the grayscale value corresponding to the pixel position in all modulation images is extracted, and then the modulation-scanning position response curve is drawn based on the grayscale value. Figure 3 shown.

[0118] In one embodiment, if Figure 5 As shown, the method of acquiring the pixel relative height based on the modulation degree-scanning position response curve and obtaining the surface three-dimensional morphology information of the object 101 under test according to the pixel relative height measurement includes: steps S201 to S204.

[0119] Step S201, selecting n data points in the peak area of ​​the modulation index-scanning position response curve as fitting points;

[0120] Step S202: Based on the fitting points, a Gaussian fitting algorithm is used to fit the modulation index-scanning position response curve to obtain a fitting curve;

[0121] Step S203, obtaining a fitting coefficient of the fitting curve, and determining a scanning position corresponding to the peak area according to the fitting coefficient, and then using the scanning position as a relative height of a corresponding pixel position;

[0122] Step S204 , summarizing the relative heights of all pixel positions, and obtaining the three-dimensional surface morphology information of the object 101 to be measured based on the relative heights of all pixel positions.

[0123] In this embodiment, after drawing the modulation index-scanning position response curve, n points (such as Figure 3 The orange points shown in the figure) are used to get the fitted Gaussian curve ( Figure 3 Specifically, the Gaussian fitting algorithm is a least squares Gaussian fitting algorithm, which can be expressed as:

[0124]

[0125] Where n is the number of selected data points, i represents the i-th data point, and its coordinates are (z i ,B i ), z i is the selected i-th scanning position, B i is the selected i-th modulation value, k0, k1 and k2 are the coefficients that need to be fitted and determined. The scanning position corresponding to the modulation peak can be determined by fitting the coefficients, and the scanning position is used as the relative height of the pixel point. After the relative height of the pixel point is obtained, the three-dimensional surface morphology information of the measured object 101 can be measured.

[0126] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0127] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A structured illumination measurement system based on binary fringe modulation, characterized in that: include: The translation stage is used to fix the object to be measured and can drive the object to be measured to move; A projection device, used for projecting two complementary binary fringe images; An imaging device, used for collecting a fringe image after being reflected by the measured object; A coaxial optical path device, arranged between the projection device and the displacement stage, and between the displacement stage and the imaging device, for irradiating the two complementary binary fringe images projected by the projection device onto the object to be measured on the displacement stage, and reflecting the fringe image reflected by the object to be measured on the displacement stage to the imaging device; An image processing unit, connected to the imaging device, is used to: Receiving a fringe image acquired by the imaging device, and processing the fringe image into a modulation image; Draw a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image; The pixel relative height is acquired based on the modulation degree-scanning position response curve, and the three-dimensional surface morphology information of the measured object is obtained according to the pixel relative height measurement.

2. The structured illumination measurement system based on binary fringe modulation according to claim 1, characterized in that: The coaxial optical path device is a microscopic optical path device, and the microscopic optical path device comprises: A first beam splitter, disposed between the projection device and the displacement stage, and between the displacement stage and the imaging device; A first tube lens is disposed between the projection device and the first beam splitter, and a focal plane of the first tube lens is close to the projection device; A second tube lens is disposed between the imaging device and the first beam splitter, and a focal plane of the second tube lens is close to the imaging device; The objective lens is arranged between the first beam splitter and the translation stage.

3. The structured illumination measurement system based on binary fringe modulation according to claim 1, characterized in that: The coaxial optical path device is a telecentric optical path device, and the telecentric optical path device comprises: A second beam splitter, disposed between the projection device and the displacement stage, and between the displacement stage and the imaging device; A first telecentric lens, disposed between the projection device and the second beam splitter; The second telecentric lens is arranged between the imaging device and the second beam splitter.

4. A structured illumination measurement method based on binary fringe modulation, applied to a structured illumination measurement system based on binary fringe modulation as claimed in any one of claims 1 to 3, characterized in that: The method comprises: Projecting two complementary binary fringe images through a projection device; The two complementary binary fringe images projected by the projection device are irradiated onto the measured object on the displacement stage through a coaxial optical path device, and the fringe images reflected by the measured object on the displacement stage are reflected to an imaging device; The reflected fringe image is collected by the imaging device, and the object to be measured is driven to move to a next position by the translation stage according to a preset motion strategy, and the fringe image is continuously collected until the preset motion strategy is executed; Receiving the fringe image collected by the imaging device through an image processing unit, and processing the fringe image into a modulation degree image; Draw a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image; The pixel relative height is acquired based on the modulation degree-scanning position response curve, and the three-dimensional surface morphology information of the measured object is obtained according to the pixel relative height measurement.

5. The structured illumination measurement method based on binary fringe modulation according to claim 4, characterized in that: The expression of the complementary binary fringe image is: in, Represents two complementary binary fringe images, x and y represent the horizontal and vertical coordinates of the image pixels respectively, ax,y represents the background intensity of the complementary binary fringe image, bx,y represents the modulation image of the complementary binary fringe image, and sgnsin2πν0x represents the square wave function with a frequency of ν0.

6. The structured illumination measurement method based on binary fringe modulation according to claim 5, characterized in that: The expression of the fringe image is: in, It represents the fringe images corresponding to the two complementary binary fringe images, Ax,y represents the background intensity of the fringe image, and Bx,y represents the modulation image of the fringe image.

7. The structured illumination measurement method based on binary fringe modulation according to claim 6, characterized in that: The step of receiving the fringe image collected by the imaging device and processing the fringe image into a modulation degree image comprises: Based on the expression of the fringe image, the fringe images corresponding to the two complementary binary fringe images are processed by differential operation to eliminate the background intensity term and the square wave function term therein; According to the following formula, the fringe images corresponding to the two complementary binary fringe images are subjected to difference processing to obtain the modulation degree image of the fringe image: Wherein, Bx,y represents the modulation image of the fringe image, and Respectively represent one of the fringe images.

8. The structured illumination measurement method based on binary fringe modulation according to claim 4, characterized in that: The step of drawing a modulation degree-scanning position response curve according to the pixel grayscale values ​​in the modulation degree image of the fringe image comprises: For each pixel position in the modulation image of the fringe image, collecting the corresponding pixel grayscale value; Based on the pixel grayscale value, a modulation degree-scanning position response curve is plotted for each pixel position.

9. The structured illumination measurement method based on binary fringe modulation according to claim 8, characterized in that: The step of obtaining the pixel relative height based on the modulation degree-scanning position response curve, and obtaining the surface three-dimensional topography information of the object under test according to the pixel relative height measurement, comprises: Selecting n data points in the peak region of the modulation index-scanning position response curve as fitting points; Based on the fitting points, a Gaussian fitting algorithm is used to fit the modulation degree-scanning position response curve to obtain a fitting curve; Obtaining a fitting coefficient of the fitting curve, and determining a scanning position corresponding to the peak area according to the fitting coefficient, and then using the scanning position as a relative height of a corresponding pixel position; The relative heights of all pixel positions are summarized, and the three-dimensional surface morphology information of the measured object is obtained based on the relative height measurements of all pixel positions.

10. The structured illumination measurement method based on binary fringe modulation according to claim 9, characterized in that: The Gaussian fitting algorithm is a least squares Gaussian fitting algorithm.

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