A non-contact detection device and method for the size of gauge blocks

Abstract

The present invention belongs to the field of metrology technology and discloses a non-contact detection device and method for the size of gauge blocks, including: a double microscopic imaging system, a microscope fixed slide rail, a periscope device, a sample positioning platform, and a precision translation platform; the double microscopic imaging system both includes microscopic objectives; the double microscopic imaging system is respectively installed on the left and right sides of the microscope fixed slide rail and slides along the microscope fixed slide rail; the sample positioning platform is fixed on the precision translation platform, and the sample positioning platform is used to place the gauge blocks to be measured; the periscope device is arranged near the microscopic objective and is used to deflect the image of the boundary of the gauge block to be measured into the microscopic imaging system. This solution does not need to measure the distance between the double microscopic imaging systems, and does not require the magnification factors of the double microscopic imaging systems to be exactly the same. As long as the two boundaries of the gauge block to be measured respectively fall into the fields of view of the corresponding microscopic imaging systems, the size measurement of the gauge block can be realized, which is suitable for the high-precision inspection of the processing errors of gauge blocks.

Description

Technical Field

[0001] The present invention belongs to the technical field of metrology, and relates to a device and method for measuring the size of gauge blocks. Background Art

[0002] Gauge blocks are generally made of wear-resistant materials, with a rectangular cross-section and a physical measuring tool having a pair of mutually parallel measuring surfaces. Generally, gauge blocks are used as length standards to transfer size values or calibrate the indication errors of measuring instruments. Since the size requirements of gauge blocks are relatively high, the national standard requires the use of a comparative measurement method for measurement, and the length difference between the standard block and the block to be measured is measured by comparing the length difference between them. And the length difference between the two is generally measured by a high-resolution length comparator. The comparator is generally divided into mechanical, optical and electrical comparators. The common measurement graduation value can reach the micron and sub-micron levels. However, contact measurement is time-consuming and laborious, and there are many factors affecting the accuracy of measurement.

[0003] Non-contact measurement has the advantages of low cost and high speed. The conventional measurement method moves the microscopic imaging system through a precision translation guide rail to respectively capture the boundaries on both sides of the gauge block, and converts the pixel distance in the picture into the size of the gauge block. However, the measurement of the gauge block size often needs to take into account both large length measurement and high measurement accuracy requirements. The traditional measurement is limited by the movement error of the precision translation guide rail, resulting in low measurement accuracy of the gauge block. Summary of the Invention

[0004] In order to solve the problem of low measurement accuracy of traditional gauge blocks, the following technical solutions are proposed.

[0005] A non-contact detection device for gauge block size, comprising: a left microscopic imaging system, a right microscopic imaging system, a microscope fixed slide rail, a left periscope device, a right periscope device, a sample positioning platform, and a precision translation platform;

[0006] Both the left microscopic imaging system and the right microscopic imaging system include microscopic objectives;

[0007] The left microscopic imaging system and the right microscopic imaging system are respectively installed on the left and right sides of the microscope fixed slide rail and slide along the microscope fixed slide rail;

[0008] The sample positioning platform is fixed on the precision translation platform, and the sample positioning platform is used to place the gauge block to be measured;

[0009] The left periscope device is arranged near the microscopic objective of the left microscopic imaging system and is used to deflect the image of the left boundary of the gauge block to be measured into the left microscopic imaging system;

[0010] The right periscope device is arranged near the microscopic objective of the right microscopic imaging system and is used to deflect the image of the right boundary of the gauge block to be measured into the right microscopic imaging system.

[0011] Preferably, both the left microscopic imaging system and the right microscopic imaging system are composed of a microscopic objective lens and an imaging CCD. The imaging CCD is used to receive the images of the left and right boundaries of the two blocks to be measured, and its gray level should be greater than 256.

[0012] Preferably, the moving accuracy of the precision translation stage is less than 0.01 mm.

[0013] Preferably, the sample positioning stage includes a gauge block placement platform and a positioning reference plane, and the positioning reference plane is perpendicular to the placement platform. It is used to place the parallelism of different gauge blocks. The sample positioning stage is installed on the precision translation stage, and the positioning reference plane is parallel to the moving direction of the precision stage. The gauge block to be measured is placed on the sample positioning stage, and the rear side of the gauge block is closely attached to the positioning reference plane.

[0014] Both the left periscope device and the right periscope device are composed of two plane mirrors. The images of the left and right boundaries of the gauge block are reflected and turned into the microscopic objective lens through the periscope device composed of two plane mirrors. It can effectively solve the problem that when the size of the gauge block to be measured is too small, the left microscopic imaging system and the right microscopic imaging system interfere, resulting in the inability to simultaneously collect the left and right boundaries of the gauge block to be measured. It can also adjust the distance between the two plane mirrors to adapt to the acquisition of the boundary images of gauge blocks of different sizes.

[0015] The left microscopic objective lens fixing slider and the right microscopic objective lens fixing slider are used to fix the microscopic objective lens and can ensure that the two microscopic objective lenses move left and right in the chute of the fixed slide rail, so as to adjust the distance between the two microscopic objective lenses to ensure that the boundaries can fall into the field of view of the microscopic objective lens when measuring gauge blocks of different lengths.

[0016] The microscopic objective lens fixed slide rail is used to fix the two microscopic objective lenses. There is a horizontal slide rail in the middle, and the microscope slider can slide on it to adjust the distance between the two microscopic objective lenses.

[0017] The left microscopic objective lens focusing device and the right microscopic objective lens focusing device are used to adjust the object distances of the left and right microscopic objective lenses to ensure that clear images of the two boundaries can be formed on the CCD.

[0018] The left imaging CCD and the right microscopic CCD are used to receive the left and right boundary images, and their gray levels should be greater than 256. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of a non-contact detection device for the size of a gauge block in Embodiment 1;

[0020] Wherein: 1. Precision translation stage, 2. Sample positioning stage, 3. Block to be measured, 4. Left periscope device, 5. Right periscope device, 6. Left microscopic objective lens, 7. Right microscopic objective lens, 10. Microscope fixed slide rail, 16. Left microscopic imaging system, 17. Right microscopic imaging system.

[0021] Figure 2 It is a digital image of the distance by which the left boundary of the block to be measured is offset from the standard block.

[0022] Figure 3 It is a digital image of the distance by which the right boundary of the block to be measured is offset from the standard block.

[0023] Figure 4 It is a schematic diagram for calculating the size of the block to be measured.

[0024] Figure 5 It is a schematic diagram of a non-contact detection device for the size of a block in Embodiment 2;

[0025] Wherein: 8. Left microscopic objective lens fixed slider, 9. Right microscopic objective lens fixed slider, 10. Microscope fixed slide rail, 11. Left microscope focusing device, 12. Right microscope focusing device, 13. Left imaging CCD, 14. Right imaging CCD, 15. Data processing unit.

[0026] Figure 6 It is a block positioning device;

[0027] Wherein: 18. Block placement platform, 19. Positioning reference plane.

[0028] Figure 7 It is a schematic diagram of the side-by-side placement of the block to be measured and the standard block;

[0029] Wherein: 20. Standard block. Detailed implementation manners

[0030] In order to make the purpose, technical solutions and advantages of this application clearer, the following will further describe this application in detail in conjunction with the accompanying drawings. Hereinafter, terms such as "left side" and "right side" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0031] Embodiment 1

[0032] A non-contact detection device for the size of a block, as Figure 1 shown, includes: left microscopic imaging system 16, right microscopic imaging system 17, microscope fixed slide rail 10, left periscope device 4, right periscope device 5, sample positioning platform 2, precision translation stage 1;

[0033] The left microscopic imaging system and the right microscopic imaging system both include a microscopic objective lens;

[0034] The left microscopic imaging system and the right microscopic imaging system are respectively installed on the left and right sides of the microscope fixed slide rail, and slide along the microscope fixed slide rail;

[0035] The sample positioning platform is fixed on the precision translation platform, and the sample positioning platform is used to place the block to be measured 3;

[0036] The left periscope device is arranged near the microscope objective lens of the left microscopic imaging system, and is used to transfer the image of the left boundary of the block to be measured into the left microscopic imaging system;

[0037] The right periscope device is arranged near the microscope objective lens of the right microscopic imaging system, and is used to fold the image of the right boundary of the block to be measured into the right microscopic imaging system.

[0038] The method of using the device is as follows: place the block to be measured and the standard block of the same size as the block to be measured side by side on the sample positioning platform; adjust the precision translation platform, the left periscope device, and the right periscope device, such as Figure 2 As shown, the left microscopic imaging system can collect a clear image of the left boundary between the block to be measured and the standard gauge block;

[0039] like Figure 3 As shown, the right microscopic imaging system can capture a clear image of the right boundary between the block to be measured and the standard gauge block. Figure 2 , Figure 3 The middle standard gauge block is placed above the block to be measured, and can also be placed below it as needed.

[0040] The measurement principle is as follows Figure 4 As shown, a standard gauge block of the same size and specification is used as a standard gauge to compare and measure the block to be measured. The block to be measured and the standard gauge block of the same size and specification as the block to be measured are placed side by side, and the distance of the block to be measured is solved by comparing the distance between the left and right boundaries. The length of the standard gauge block is recorded as L, the distance between its left boundary and the standard gauge block is recorded as Δx1, and the distance between its right boundary and the standard gauge block is recorded as Δx2. The length L between the left and right sides of the block to be measured is x The length L between the left and right sides of the block to be measured can be solved by converting the pixel size in the digital image into the actual corresponding space size using the image processing method in the prior art. x .

[0041] Embodiment 2

[0042] A non-contact measuring device for measuring block size, such as Figure 5As shown in the figure, the left microscopic imaging system consists of a left microscopic objective lens 6, a left microscopic objective lens fixed slider 8, a left microscope focusing device 11, and a left imaging CCD 13;

[0043] The left microscopic objective lens fixed slider is used to fix the left microscopic objective lens, and the left microscopic objective lens fixed slider is assembled on the left side of the microscope fixed slide rail; the left microscopic objective lens focusing device is used to adjust the object distance of the left microscopic objective lens;

[0044] The right microscopic imaging system consists of a right microscopic objective lens 7, a right microscopic objective lens fixed slider 9, a right microscope focusing device 12, and a right imaging CCD 14;

[0045] The left imaging CCD and the right imaging CCD transmit the data they collect to the data processing unit 15 for data processing, so as to obtain the length between the left and right sides of the block to be measured.

[0046] The sample positioning platform is as Figure 6 shown, and includes a gauge block placement platform 18 and a positioning reference plane 19, and the positioning reference plane is perpendicular to the placement platform.

[0047] Embodiment 3

[0048] A non-contact detection method for the size of a gauge block. Place a standard gauge block with the same specification as the gauge block to be measured on the gauge block placement platform. The rear side of the gauge block to be measured is closely attached to the positioning reference plane. Use the left microscopic imaging system and the right microscopic imaging system to image the left boundary and the right boundary of the standard gauge block in the length direction of the standard gauge block respectively, and the CCD collects the digital images of the left boundary and the right boundary of the standard gauge block;

[0049] Keep the parameters of the left microscopic imaging system and the right microscopic imaging system unchanged. The precision translation platform moves the standard gauge block a distance d along the length direction of the standard gauge block. Again, use the left microscopic imaging system and the right microscopic imaging system to image the left boundary and the right boundary of the standard gauge block in the length direction of the moved standard gauge block respectively, and the CCD collects the digital images of the left boundary and the right boundary of the moved standard gauge block;

[0050] Use the digital image correlation algorithm to calculate the number of pixels L1 that the digital image of the left boundary of the standard gauge block moves and the number of pixels L2 that the digital image of the right boundary of the standard gauge block moves;

[0051] Thus, calibrate the magnification k1 of the left microscopic imaging system and the magnification k2 of the right microscopic imaging system; where:

[0052] The gauge block to be measured and the standard gauge block are placed side by side, as Figure 7As shown, the rear side of the block 3 to be measured is placed on the block placement platform 18 close to the front side of the standard block 20. The left microscopic imaging system and the right microscopic imaging system are used to image the left boundary and the right boundary of the block to be measured respectively, and the digital images of the left boundary and the right boundary of the block to be measured are collected by the CCD. Using the digital image correlation algorithm, the number of pixels by which the left boundary of the block to be measured is offset from the standard block is denoted as d1, and the distance by which the right boundary of the block to be measured is offset from the standard block is denoted as d2.

[0053] Then the length L between the left and right sides of the block to be measured x is: L x = L+(d2*k2 - d1*k1).

[0054] The digital image correlation algorithm is used to judge the similarity of two images, and the correlation coefficient of exactly the same is 1. Using this algorithm, the number of pixels by which the similar feature regions in the two images move can be calculated, that is, the position difference of a specific feature region in the two images. The formula of the digital image correlation algorithm is:

[0055]

[0056] where f(x i , y i ) is the gray level distribution of the feature region image in the first image, is the average gray level of this region, g(x i + u, y i + v) is the gray level distribution of the trial area in the second image, is the average gray level of this region, and u, v are the trial displacements, that is, the number of pixels by which the trial area in the second image deviates from the feature region in the first image. Through this algorithm, the position coordinate offset where the trial area in the second image coincides with the feature region in the first image is found.

[0057] By performing difference processing on the second image, the gray level distribution of the sub-pixel position image is found, and sub-pixel displacement calculation can be realized through correlation operations.

[0058] The optical axes of the left microscopic imaging system and the right microscopic imaging system are perpendicular to the surface of the block to be measured. There is no need to measure the distance between the two imaging systems. It is only necessary to ensure that the two boundaries of the block to be measured fall on the centers of the CCD targets of the two imagings respectively. When taking the boundary digital image, rotate the CCD angle so that the boundary line of the standard measurement block remains vertical in the image.

[0059] This scheme has nothing to do with the distance between the double microscopic imaging systems. There is no need to measure the distance between the double microscopic imaging systems, and it is not necessary for the magnification factors of the double microscopic imaging systems to be exactly the same. It is only necessary to ensure that the two boundaries of the block to be measured fall into the fields of view of the corresponding microscopic imaging systems respectively to realize the measurement of the block size, which is applicable to the high-precision inspection of the processing error of the block.

Claims

1. A non-contact measuring device for the size of gauge blocks, characterized in that: include: Left microscopic imaging system, right microscopic imaging system, microscope fixed slide rail, left periscope device, right periscope device, sample positioning platform, precision translation platform, standard gauge block; The left microscopic imaging system and the right microscopic imaging system both include a microscopic objective lens; The left microscopic imaging system and the right microscopic imaging system both include a microscope objective lens and an imaging CCD and are respectively installed on the left and right sides of the microscope fixed slide rail and slide along the microscope fixed slide rail; The sample positioning platform is fixed on the precision translation platform. The sample positioning platform is used to place the block to be measured. The sample positioning platform includes a placement platform and a positioning reference plane. The positioning reference plane is perpendicular to the placement platform. The rear side of the gauge block is close to the positioning reference plane. The left periscope device and the right periscope device are respectively composed of two plane reflectors. The left periscope device is arranged near the microscope objective lens of the left microscopic imaging system, and is used to fold the image of the left boundary of the block to be measured into the left microscopic imaging system. The right periscope device is arranged near the microscope objective lens of the right microscopic imaging system, and is used to transfer the image of the right boundary of the block to be measured into the right microscopic imaging system; The block to be measured and the standard block are placed side by side on the sample positioning platform. The size of the block to be measured is calculated by comparing the distance between the left and right boundaries. The calculation formula is: Lx=L+Δx1-Δx2 Wherein, L is the length of the standard gauge block, Δx1 is the distance between the left boundary and the standard gauge block, and Δx2 is the distance between the right boundary and the standard gauge block.

2. The non-contact detection device for gauge block size according to claim 1, characterized in that: The moving accuracy of the precision translation platform is less than 0.01mm.

3. The non-contact detection device for gauge block size according to claim 1, characterized in that: The digital image correlation algorithm is used to calculate the distance Δx1 between the left boundary and the standard gauge block and the distance Δx2 between the right boundary and the standard gauge block.

4. A non-contact measuring device for the size of gauge blocks according to any one of claims 1 to 3, characterized in that: The left microscopic imaging system and the right microscopic imaging system are both composed of a microscope objective, a microscope objective fixing slider, a microscope focusing device, and an imaging CCD; the microscope objective fixing slider is used to fix the microscope objective, and the microscope objective fixing slider is assembled on the microscope fixed slide rail; the microscope objective focusing device is used to adjust the object distance of the microscope objective.

5. A non-contact detection method for the size of gauge blocks, characterized in that: The measurement is performed using the non-contact gauge block size detection device of claim 1.

6. The non-contact detection method for the size of gauge blocks according to claim 5, characterized in that: The block to be measured and a standard gauge block of the same size as the block to be measured are placed side by side on the sample positioning platform; the precision translation platform, the left periscope device and the right periscope device are adjusted so that the left microscopic imaging system can collect a clear image of the left boundary between the block to be measured and the standard gauge block, and the right microscopic imaging system can collect a clear image of the right boundary between the block to be measured and the standard gauge block; the distance of the block to be measured is solved by comparing the offset distance between the left boundary and the right boundary.

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