A calibration system and method for geometric features of three-dimensional interference fringes

Abstract

The present invention provides a system and method for calibrating the geometric features of three-dimensional interference fringes. The system combines a high-precision linear motorized translation stage with a matrix camera. A control program is used to manipulate the translation stage along the projection direction of the interference fringes, while the camera is controlled to capture interference fringes at different locations to produce a three-dimensional image of the fringes. A spatial Fourier transform, Gaussian fitting, and a maximum position extraction algorithm are used to calculate the spatial frequency of the variations in light and dark fringes, thereby calibrating the fringe spacing of the interference fringe system based on pixel size. Image binarization and an edge detection algorithm are used to extract the fringe boundary contours, calibrate the height and width of the interference fringe area, and ultimately evaluate the geometric features of the three-dimensional interference fringe system. This system and method can provide a more comprehensive calibration of interference fringe systems.

Description

Technical Field

[0001] The present invention relates to the technical field of interference fringe geometric feature calibration systems and methods, and in particular, to a three-dimensional interference fringe geometric feature calibration system and method. Background Art

[0002] Existing interference fringe calibration systems and methods only implement two-dimensional calibration through a rotating disk or camera with small holes, which fails to fully evaluate the geometric characteristics of the interference fringes, causing some processing and measurement systems based on interference technology to produce large systematic errors. Summary of the Invention

[0003] In response to the technical issues mentioned in the background art, a system and method for calibrating the geometric characteristics of three-dimensional interference fringes is provided. This invention primarily provides a novel system and method for calibrating the geometric characteristics of three-dimensional interference fringe systems. This system and method can calibrate the geometric characteristics of interference fringe systems in three dimensions, including fringe spacing, fringe area height, and width, thereby providing a more comprehensive evaluation of the interference fringe system. The system and method are suitable for calibrating interferometry-based processing and measurement systems, such as laser Doppler velocity, distance, and vibration meters, and can effectively reduce system errors.

[0004] The technical means adopted in the present invention are as follows:

[0005] A calibration system for geometric features of three-dimensional interference fringes includes a control module, a displacement module, a data acquisition module and an analysis module.

[0006] Furthermore, the control module sets and controls the total moving distance, moving position and moving speed of the translation stage through a control program obtained by Matlab software in the computer; and at the same time, sets and controls the information collected by the data acquisition module through a camera control program obtained by Matlab software.

[0007] Furthermore, the displacement module is connected to the control module; when the displacement module receives the instruction from the control module, it moves along the optical axis according to preset movement parameters and collects position information of the displacement stage at the same time.

[0008] Furthermore, the data acquisition module is connected to the control module; the data acquisition module captures interference fringe images at different positions according to set shooting parameters.

[0009] Furthermore, the analysis module is connected to the displacement module and the data acquisition module; the position information of the displacement stage collected by the displacement module and the fringe image collected by the data acquisition module are transmitted to the computer; the fringe image is processed by a calibration program obtained by the Matlab software in the computer to obtain the spacing, fringe area height and width information of the interference fringes in the fringe image.

[0010] The present invention also includes a method for calibrating the geometric features of three-dimensional interference fringes, comprising the following steps:

[0011] Step 1: Set the matrix camera on the electronically controlled displacement module;

[0012] Step 2: Setting the displacement module in the projection direction of the interference fringes to be calibrated so that the displacement module can move along the projection direction;

[0013] Step 3: Connect the displacement module and the matrix camera to a computer, control the displacement module to move along the optical axis through a software control program, and control the camera through a camera control program to capture interference fringes at different positions to obtain a three-dimensional image I(x, y, z) of the fringes;

[0014] Step 4: Define Maxpos as the function for searching the maximum position of the sequence, Gaussian as the Gaussian fitting function, FFT as the fast Fourier transform function, D as the size of a single pixel, the x-axis being perpendicular to the interference fringe, and Fourier transform along the x-direction of the image to obtain the spatial frequency f of the fringe. d , introduce pixel size D to calibrate the interference fringe spacing d(y, z);

[0015] Step 5: Binarize the image and perform edge detection to extract the fringe boundary contour and obtain the upper and lower boundary coordinates y of the interference fringe contour T ,y B and the left and right boundary coordinates x L , x R , the pixel size D is introduced to calibrate the stripe area height h(x, z) and the stripe area width w(y, z).

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The present invention proposes a calibration system that combines a matrix camera with a high-precision translation stage. The camera and translation stage control program are used to capture images of the interference fringe system at different positions along the optical axis to obtain three-dimensional image information of the interference fringes.

[0018] 2. The present invention establishes an interference fringe calibration algorithm, performs image processing on the collected three-dimensional interference fringe images, and obtains fringe spacing, fringe area height and width information, thereby more comprehensively calibrating the interference fringe system.

[0019] 3. The present invention is widely applicable to calibrating processing and measurement systems based on interference technology, such as laser Doppler velocity, distance and vibration measuring instruments, and effectively reduces system errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 Schematic diagram of the calibration method of the present invention.

[0022] Figure 2 Schematic diagram of the calibration system of the present invention.

[0023] In the figure: 1. Computer; 2. Camera; 3. Motorized translation stage. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] like Figure 1As shown, the present invention provides a method for calibrating the geometric features of three-dimensional interference fringes, which specifically includes the following steps:

[0027] S1. Mount the matrix camera on the electronically controlled translation stage.

[0028] S2. Place the translation stage in the projection direction of the interference fringes to be calibrated, allowing the translation stage to move along the projection direction.

[0029] S3. Connect the stage and camera to the computer.

[0030] S4. The control program controls the translation stage to move along the optical axis while controlling the camera to capture interference fringes at different positions to obtain a three-dimensional image I (x, y, z) of the fringes.

[0031] S5. Define Maxpos as the function for searching for the maximum position of a sequence, Gaussian as the Gaussian fitting function, FFT as the fast Fourier transform function, D as the size of a single pixel, and the x-axis perpendicular to the interference fringe. Perform a Fourier transform along the x-axis of the image to obtain the spatial frequency of the fringe:

[0032] f d =Maxpos(Gaussian|FFT(I(x,y,z))|) (1);

[0033] S6. Introduce pixel size D to calibrate the interference fringe spacing:

[0034]

[0035] S7. Binarize the image and perform edge detection to extract the fringe boundary contours and obtain the upper and lower boundary coordinates y of the interference fringe contours. T ,y B and the left and right boundary coordinates x L , x R ,

[0036] S8. Introduce pixel size D to calibrate the stripe area height:

[0037] h(x, z)=D·(y T (x, z)-y B (x, z)) (3);

[0038] and stripe area width:

[0039] w(y, z) = D·(x R (y, z)-x L (y, z)) (4);

[0040] The above process can more comprehensively evaluate the geometric characteristics of the interference fringe system.

[0041] See also Figure 2 In this embodiment, the three-dimensional calibration system for the geometric features of interference fringes includes a control module, a displacement module, a data acquisition module, and an analysis module. The control module sets and controls the total moving distance, moving position, and moving speed of the displacement stage through a control program in a computer. At the same time, the camera control program sets and controls the information collected by the data acquisition module.

[0042] The displacement module is connected to the control module; when the displacement module receives the instruction from the control module, it moves along the optical axis according to the preset movement parameters and collects the position information of the displacement stage;

[0043] The data acquisition module is connected to the control module; the data acquisition module captures interference fringe images at different positions according to set shooting parameters;

[0044] The analysis module is connected to the displacement module and the data acquisition module; the position information of the displacement stage acquired by the displacement module and the fringe image acquired by the data acquisition module are transmitted to the computer; the fringe image is processed by a calibration program in the computer to obtain the spacing, fringe area height and width information of the interference fringes in the fringe image.

[0045] In a specific implementation, the translation stage is placed along the projection direction of the interference fringes so that the translation stage can move along the projection direction of the fringes; a matrix camera is installed on the translation stage to ensure that the height and position of the camera can capture the entire imaging area of the interference fringes; the translation stage and the camera are connected to the computer with cables respectively.

[0046] The serial numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts not described in detail in a particular embodiment, please refer to the relevant description of other embodiments. In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented by other means.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calibrating the geometric features of three-dimensional interference fringes, characterized in that: The following steps are involved: Step 1: Set the matrix camera on the electronically controlled displacement module; Step 2: Setting the displacement module in the projection direction of the interference fringes to be calibrated so that the displacement module can move along the projection direction; Step 3: Connect the displacement module and the matrix camera to a computer, and use the control program obtained from Matlab software to control the displacement module to move along the optical axis. At the same time, use the camera control program to control the camera to capture interference fringes at different positions to obtain a three-dimensional image of the fringes. ; Step 4: Definition Maxpos It is the function for searching the maximum position of a sequence. is the Gaussian fitting function, is the fast Fourier transform function, is the size of a single pixel, x The axis is perpendicular to the interference fringes and is along the image x The spatial frequency of the stripes is obtained by Fourier transform , introducing pixel size Calibrate interference fringe spacing ; Step 5: Binarize the image and perform edge detection to extract the fringe boundary contour and obtain the upper and lower boundary coordinates of the interference fringe contour. and left and right boundary coordinates , introducing pixel size Calibrate the stripe area height and stripe area width . The spatial frequency of the fringes : ； Interference fringe spacing : ； The stripe area height ; The width of the stripe area is .

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