Laser measurement equipment and measurement method for detecting appearance error of precise sample

Abstract

The invention relates to a laser measuring device and measuring method for detecting the appearance error of a precise sample, and the measuring device comprises a polarized laser light source which is configured to emit polarized laser; a spectroscope configured to receive the polarized laser light and guide the polarized laser light to a sample, and to redirect light reflected from the sample; the quarter-wave plate is arranged between the spectroscope and the sample; the sample clamping device is configured to clamp a sample and enable the sample to rotate around a central shaft of the sample clamping device; a concave lens configured to receive the light redirected by the spectroscope; and a display panel configured to receive light from the concave lens and display a light pattern; the centers of the polarization laser light source, the spectroscope and the sample clamping device are collinear in the vertical direction; the centers of the spectroscope, the concave lens and the display panel are collinear in the direction perpendicular to the vertical direction. According to the invention, rapid and high-precision detection of parallelism, verticality and concentricity of a precise sample can be realized on the same equipment, and the device has the advantages of wide measurement range, simple operation, low cost and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of testing devices, and in particular to a laser measuring device and method for detecting the shape error of precision samples. Background Technology

[0002] With the development of testing technology, high-precision thermodynamic testing devices and high-precision testing are of great significance to the development of aerospace, electronic semiconductor and other fields. Similarly, high-precision testing places increasingly higher demands on the processing accuracy of test samples. To meet the testing requirements of high-precision testing (such as CTE testing of near-zero expansion materials), the high-precision testing devices have high requirements for sample processing. Currently, high-precision laser thermal dilatometers, depending on their principles, often process samples into specific shapes such as small cylinders with parallel surfaces or cylinders with spherical surfaces, because their accuracy reaches 10... -8 ~10 -9 Even slight deformations in the sample dimensions can affect the test results. High-precision testing places high demands on the parallelism, perpendicularity, and concentricity of the two spherical surfaces of the sample during machining.

[0003] Currently, the parallelism, perpendicularity, and concentricity of solid objects or devices are typically measured using different methods and various devices. Parallelism is usually determined by measuring the reflected light from two light-transmitting surfaces using a laser interferometer. However, this requires the formation of interference fringes, placing high demands on the quality of the reference mirror and sample surface. Laser interferometers also have a narrow measurement range and complex fitting calculations, often limiting their application to the parallelism testing of optical components. Perpendicularity is relatively cumbersome, typically using a contrast goniometer. The test sample is placed on a V-groove, and its cylindrical sidewall is manually rubbed. The reading is then obtained by visually observing the scale value on the reticle. Contrast goniometers have large perpendicularity measurement errors and are unsuitable for high-precision sample testing. While coordinate measuring machines (CMMs) can simultaneously measure parallelism, perpendicularity, and concentricity of two spherical surfaces, they require multi-point data acquisition and fitting, limiting their speed. Furthermore, the uneven thermal expansion coefficients of the three axes can cause measurement accuracy distortion and instability in CMMs.

[0004] The aforementioned testing methods suffer from drawbacks such as limited testing and inspection items, narrow measurement range, susceptibility to errors in visual readings, high cost, and low efficiency. Therefore, a measuring device and method are needed to overcome one or more of these problems. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a laser measurement device and method for detecting the shape error of precision samples. It can realize rapid and high-precision detection of the parallelism, perpendicularity and concentricity of precision samples on the same device, and has the advantages of wide measurement range, simple operation, low cost and high efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] In a first aspect, the present invention provides a laser measuring device for detecting the shape error of precision samples, which adopts the following technical solution: A laser measuring device for detecting the shape error of a precision sample, comprising: A polarized laser source, configured to emit polarized laser light; A beam splitter is configured to receive the polarized laser and direct it toward the sample, as well as to redirect light reflected from the sample. A quarter-glass slide is placed between the beam splitter and the sample; A sample clamping device configured to clamp a sample and rotate the sample about its central axis; A concave lens, configured to receive light redirected by the beam splitter; and The display panel is configured to receive light from the concave lens and display a light pattern. The polarized laser source, the beam splitter, and the sample clamping device are collinear in the vertical direction. The beam splitter, the concave lens, and the display panel are collinear in a direction perpendicular to the vertical direction.

[0008] Furthermore, the aforementioned laser measurement equipment also includes a high-precision reference rail, with the beam splitter mounted on the high-precision reference rail and the sample clamping device fixed below the high-precision reference rail.

[0009] Furthermore, the aforementioned laser measurement equipment also includes a high-precision dial indicator, which is configured to detect whether the sample is clamped in the center.

[0010] Furthermore, in the aforementioned laser measurement device, the quarter-glass slide is configured to delay the polarized laser by a π / 4 phase angle.

[0011] Furthermore, in the aforementioned laser measurement device, the concave lens can be replaced with a concave lens with a different focal length to achieve measurements in different ranges.

[0012] Furthermore, in the aforementioned laser measuring device, the display panel has a scale, and the display panel can rotate in a plane around its center point.

[0013] Furthermore, the aforementioned laser measurement device also includes data processing software, which is configured to automatically calculate parallelism, perpendicularity, and concentricity based on the input sample size parameters and the data collected from the display panel.

[0014] Secondly, the present invention provides a laser measurement method for detecting the shape error of precision samples, which adopts the following technical solution: A laser measurement method for detecting the shape error of a precision sample, using the laser measurement device described in any one of the first aspects above, comprising: The sample is fixed in the sample clamping device; The sample is rotated about its central axis using the sample clamping device. The polarized laser is directed to the surface of the sample through the beam splitter and the quarter glass slide; The light reflected from the sample surface is received, and the reflected light reaches the display panel via the beam splitter and the concave lens to form a light pattern. Observe and measure the size of the light pattern; and The shape error parameters of the sample are calculated based on the measured dimensions.

[0015] Furthermore, in the above laser measurement method, the shape error parameter is perpendicularity, and the method further includes: As the sample rotates, a circular aperture is observed to form on the display panel. Measure the radius of the circular aperture; and The perpendicularity is calculated based on the radius of the circular aperture, the magnification of the concave lens, and the optical path distance.

[0016] Furthermore, in the above laser measurement method, the shape error parameter is parallelism, and the method further includes: With the first side of the sample facing upwards, measure the first radius of the first circular aperture formed on the display panel; Flip the sample so that its second side is facing up and re-clamp it in the center; While the sample rotates, the second radius of the second circular aperture formed on the display panel is measured; and The parallelism is calculated based on the first radius and the second radius.

[0017] In summary, compared with the prior art, the present invention has at least one of the following beneficial technical effects: The laser measurement device provided by this invention, through a specific optical path arrangement of a polarized laser source, beam splitter, quarter-glass slide, sample clamping device, concave lens, and display panel, can comprehensively detect three dimensional error parameters of precision samples—parallelism, perpendicularity, and concentricity—on a single device, avoiding the cumbersome operation of using multiple different devices for separate measurements. This device utilizes the reflection characteristics of polarized laser and the phase delay effect of the quarter-glass slide to effectively eliminate stray light interference and improve the measurement signal-to-noise ratio. The sample clamping device rotates the sample around its central axis, and the changes in the light pattern formed on the display panel can intuitively reflect the tilt degree of the sample surface. The concave lens amplifies the reflected light, thereby improving measurement sensitivity and resolution. The overall device has a simple structure, clear optical path, and convenient operation, enabling rapid and efficient detection. It is suitable for the high-precision testing and quality inspection needs of sample processing in fields such as aerospace and electronic semiconductors. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the structure of a laser measurement device according to an embodiment of the present disclosure is shown.

[0020] Figure 2 A schematic diagram of verticality measurement and analysis according to an embodiment of the present disclosure is shown.

[0021] Figure 3 A schematic diagram of parallelism measurement and analysis according to an embodiment of the present disclosure is shown.

[0022] Figure 4 A schematic diagram of concentricity measurement and analysis according to an embodiment of this disclosure is shown. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0024] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment in the following embodiments have their own emphasis; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0025] The method steps described in this embodiment of the invention can be executed in the order described in the specific implementation, or the execution order of each step can be adjusted according to actual needs, provided that the technical problem can be solved. These are not listed one by one here.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Reference Figure 1 The present invention illustrates a laser measuring device according to an embodiment of the present invention, which is used to detect the shape error of a precision sample, including the measurement of parallelism, perpendicularity and concentricity.

[0028] The laser measurement equipment includes a He-Ne laser 1-1, a transmission fiber 1-2, a laser source 1-3, a beam splitter 1-4, a concave lens 1-5, a quarter glass slide 1-6, a sample 1-7, an electric three-jaw chuck 1-8, and a display panel 1-9.

[0029] The He-Ne laser 1-1 serves as a specific implementation of a polarized laser source, used to generate laser light with a specific polarization state. A transmission fiber 1-2 connects the He-Ne laser 1-1 to the laser source 1-3, enabling laser transmission. The laser source 1-3 is configured to emit polarized laser light, which shines downwards in a vertical direction.

[0030] Beam splitters 1-4 are configured to receive polarized laser light and direct it towards samples 1-7, as well as to redirect light reflected from samples 1-7. Beam splitters 1-4 are mounted on a high-precision reference rail.

[0031] A quarter-glass slide 1-6 is positioned between the beam splitter 1-4 and the sample 1-7, with the quarter-glass slide 1-6 adhering tightly to the lower surface of the beam splitter 1-4. The quarter-glass slide 1-6 is configured to perform polarization laser beam refraction. Phase angle delay is used to achieve phase delay of the polarization state of light.

[0032] The electric three-jaw chuck 1-8 serves as a sample clamping device, configured to hold sample 1-7 and rotate it around its central axis. The electric three-jaw chuck 1-8 is horizontally fixed below a high-precision reference guide rail and its rotation is electrically controlled, driving the center rotation of the sample 1-7 being measured. The laser measuring equipment also includes a high-precision dial indicator, configured to detect whether sample 1-7 is centered during clamping.

[0033] The polarized laser light passes through beam splitter 1-4 and then through quarter-glass slide 1-6, illuminating the surface of sample 1-7 and being reflected. The light reflected from the surface of sample 1-7 passes through quarter-glass slide 1-6 again and is redirected to the horizontal direction at beam splitter 1-4.

[0034] Concave lens 1-5 is configured to receive light redirected by beam splitter 1-4. Concave lens 1-5 has a specific focal length, serving to magnify the image. Concave lens 1-5 can be replaced with concave lenses of different focal lengths to achieve measurements within different ranges.

[0035] Display panels 1-9 are configured to receive light from concave lenses 1-5 and display light patterns. Display panels 1-9 have a scale with graduations extending outwards from their center, calculated according to specific rules. Display panels 1-9 are capable of planar rotation around their center point.

[0036] The laser source 1-3, beam splitter 1-4, and motorized three-jaw chuck 1-8 are collinear in the vertical direction. The beam splitter 1-4, concave lens 1-5, and display panel 1-9 are collinear in the horizontal direction perpendicular to the vertical direction.

[0037] The laser measurement equipment also includes data processing software, which is configured to automatically calculate parallelism, perpendicularity, and concentricity based on the input sample size parameters and the data collected from display panels 1-9.

[0038] The laser measurement equipment is suitable for inspecting small cylindrical samples with two parallel surfaces and cylindrical samples with two spherical surfaces. The equipment is equipped with cylindrical standard samples with good parallelism and perpendicularity for calibration of corresponding tests, as well as standard samples with good concentricity and two spherical surfaces for calibration of corresponding tests. The measurement accuracy of the laser measurement equipment can reach 10... -8 ~10 -9 / K level, suitable for CTE test sample detection of near-zero expansion materials.

[0039] Figure 2 A schematic diagram of verticality measurement and analysis is shown, illustrating the optical path structure and geometric relationship of the laser measurement equipment during verticality measurement.

[0040] The perpendicularity measurement method uses the aforementioned laser measurement equipment and includes the following steps: The sample is fixed in a sample holder, and a high-precision dial indicator is used to ensure the sample is centered. The sample is rotated about its central axis using the sample holder. A polarized laser is directed to the surface of the sample through a beam splitter and a quarter-glass slide. Light reflected from the sample surface is received; the reflected light passes through the beam splitter and a concave lens to reach the display panel and form a light pattern.

[0041] Observe the circular aperture formed on the display panel as the sample rotates. When there is a perpendicularity deviation on the sample surface, the reflected light will deviate from the original optical path, and after being magnified by the concave lens, it will form an offset spot or aperture on the display panel. The center of the aperture coincides with the center of the scale on the display panel. Observe and measure the size of the light pattern, and read the aperture radius reading according to the scale.

[0042] Figure 2 The distances H1 from the sample surface to the center of the beam splitter, H2 from the center of the beam splitter to the display panel, and L from the display panel to the concave lens are labeled. H1 is the vertical distance between the upper surface of the sample and the center of the beam splitter. H2 is the horizontal distance between the center of the beam splitter and the display panel. The distance L from the display panel to the concave lens is used as an optical path parameter to calculate magnification and measurement results.

[0043] The formula for calculating the magnification m of a concave lens is: Where f is the focal length of the concave lens, H1 is the distance from the sample surface to the center of the beam splitter, and H2 is the distance from the center of the beam splitter to the display panel.

[0044] The shape error parameter of the sample is calculated based on the measured dimensions. When the shape error parameter is perpendicularity, it is calculated based on the radius of the circular aperture, the magnification of the concave lens, and the optical path distance. The formula for calculating the perpendicularity θ is: [Formula omitted for brevity] Where R is the measured aperture radius, m is the magnification of the concave lens, H1 is the distance from the sample surface to the center of the beam splitter, and H2 is the distance from the center of the beam splitter to the display panel.

[0045] The above-described method for measuring perpendicularity utilizes the principle of light reflection to elongate and amplify minute angular differences. These differences are further magnified by a concave lens with a specific focal length, allowing the distance to be observed and quantitatively read on a display panel, achieving perpendicularity measurements down to the second. The perpendicularity θ is obtained by inputting the radius parameter into the data processing software.

[0046] Figure 3 A schematic diagram of parallelism measurement and analysis is shown, illustrating the optical path arrangement and related dimensional parameters used to measure the parallelism of precision samples. Figure 3 The distance H1 from the sample surface to the center of the beam splitter and the distance H2 from the center of the beam splitter to the display panel are marked.

[0047] When the shape error parameter is parallelism, the laser measurement method includes two methods.

[0048] The first parallelism measurement method includes the following steps: With the first side of the sample facing upwards, fix the sample in the sample clamping device, and use a high-precision dial indicator to ensure that the sample clamping is centered. Use the sample clamping device to rotate the sample around its central axis, and observe the formed circular aperture on the display panel, with the center of the aperture coinciding with the center of the scale on the display panel. Measure the first radius R1 of the first circular aperture formed on the display panel.

[0049] Flip the sample so that its second side faces upward and re-clamp it in the center, using a high-precision dial indicator to ensure the sample is centered. While rotating the sample, observe the circular aperture formed on the display panel; the center of the aperture should coincide with the center of the display panel's scale. Measure the second radius R2 of the second circular aperture formed on the display panel.

[0050] The parallelism is calculated based on the first radius R1 and the second radius R2. The formula for calculating parallelism ∥ is: Where R1 is the first radius of the first circular aperture, R2 is the second radius of the second circular aperture, m is the magnification of the concave lens, H1 is the distance from the sample surface to the center of the beam splitter, and H2 is the distance from the center of the beam splitter to the display panel.

[0051] The second parallelism measurement method uses a standard sample with good parallelism for calibration. The standard sample is clamped in a sample holder, and a high-precision dial indicator is used to ensure the standard sample is centered. The sample holder is used to rotate the standard sample around its central axis, adjusting the plane to be level so that the circular aperture on the display panel approaches a single point; this is the calibrated standard sample surface.

[0052] Place the sample to be tested on the calibrated standard sample surface, turn on the laser, observe the distance of the light spot offset from the center point, and measure the offset distance d. The formula for calculating parallelism ∥ is: Where R is the measured spot offset distance, m is the magnification of the concave lens, H1 is the distance from the sample surface to the center of the beam splitter, and H2 is the distance from the center of the beam splitter to the display panel.

[0053] Figure 4 A schematic diagram of concentricity measurement and analysis is shown. The concentricity test is performed on a small cylindrical sample with spherical surfaces on both sides. Figure 4 The distance H1 from the sample surface to the center of the beam splitter and the distance H2 from the center of the beam splitter to the display panel are marked.

[0054] The concentricity measurement method includes the following steps: The sample to be tested is clamped in a sample clamping device, and a high-precision dial indicator is used to ensure the sample is centered. The sample is rotated about its central axis using the sample clamping device. A polarized laser is directed to the spherical surface of the sample through a beam splitter and a quarter-glass slide. The light reflected from the spherical surface of the sample is received; the reflected light passes through the beam splitter and a concave lens to reach the display panel and form a light pattern.

[0055] Due to the discrepancy between the center of the sphere and the center of the cylinder, the reflected light is deflected by an angle θ relative to the incident light. When the sample rotates around its cylindrical central axis, a circular aperture is observed on the display panel, with its center coinciding with the center of the scale on the display panel. The radius R of the circular aperture is measured.

[0056] Calculate the concentricity of the sample sphere and cylinder based on the measured aperture radius R. Concentricity The calculation formula is: Where r is the radius of the sphere and θ is the deflection angle of the reflected light.

[0057] When the concentricity deviation is small, sinθ approaches tanθ, and the concentricity is approximately: in: Where R is the measured aperture radius, m is the magnification of the concave lens, H1 is the distance from the sample surface to the center of the beam splitter, H2 is the distance from the center of the beam splitter to the display panel, and r is the radius of the sphere.

[0058] Input the aperture radius R, spherical radius r, and optical path distance parameters into the data processing software, and the software will automatically calculate the concentricity between the spherical surface and the cylinder at one end of the sample.

[0059] The concentricity of the other spherical surface can be measured using the same method. Flip the sample so that the other spherical surface faces upwards, re-clamp it in the center, and rotate the sample around its central axis. Measure the radius of the circular aperture formed on the display panel, and calculate the concentricity of the other spherical surface using the formula described above.

[0060] The laser measurement device and method of this invention are based on the principles of polarized light reflection and geometric optical magnification to detect the shape errors of precision samples. Polarized laser light is reflected after being guided to the sample surface by a beam splitter. When the sample surface is tilted or deviated, the reflected light is deflected relative to the incident light. The use of a quarter-glass slide alters the polarization state of the light, giving the reflected light different polarization directions from the incident light, thus achieving optical path separation at the beam splitter and reducing stray light interference. The sample clamping device rotates the sample around its central axis, causing the reflected light to form a circular aperture on the display panel. By measuring the aperture radius and combining it with the magnification of the concave lens and the optical path distance parameters, the perpendicularity, parallelism, or concentricity of the sample can be calculated.

[0061] In some aspects, embodiments of the present invention may have one or more of the following beneficial technical effects. The laser measuring device of the present invention can comprehensively detect three shape error parameters—parallelism, perpendicularity, and concentricity—of a precision sample on the same device, avoiding the need for separate measurements using multiple different devices. The concave lens amplifies minute angular deviations, resulting in a visible change in aperture size on the display panel, improving measurement sensitivity and resolution. The scale on the display panel allows for direct reading, simplifying operation and reducing human reading errors. The data processing software can automatically calculate shape error parameters based on input parameters, improving measurement efficiency. The concave lens can be replaced with concave lenses of different focal lengths to meet measurement needs across different ranges. The overall device has a simple structure and clear optical path, enabling rapid detection. In some cases, it is suitable for the inspection of high-precision sample processing quality in fields such as aerospace and electronic semiconductors.

[0062] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0063] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a system including a processing module or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser measuring device for detecting the shape error of precision samples, characterized in that, include: A polarized laser source, configured to emit polarized laser light; A beam splitter is configured to receive the polarized laser and direct it toward the sample, as well as to redirect light reflected from the sample. A quarter-glass slide is placed between the beam splitter and the sample; A sample clamping device configured to clamp a sample and rotate the sample about its central axis; A concave lens, configured to receive light redirected by the beam splitter; as well as The display panel is configured to receive light from the concave lens and display a light pattern. The polarized laser source, the beam splitter, and the sample clamping device are collinear in the vertical direction. The beam splitter, the concave lens, and the display panel are collinear in a direction perpendicular to the vertical direction.

2. The laser measuring device according to claim 1, characterized in that, It also includes a high-precision reference rail, the beam splitter is mounted on the high-precision reference rail, and the sample clamping device is fixed below the high-precision reference rail.

3. The laser measuring device according to claim 1, characterized in that, It also includes a high-precision dial indicator, which is configured to detect whether the sample is clamped in the center.

4. The laser measuring device according to claim 1, characterized in that, The quarter-glass slide is configured to delay the polarized laser by a phase angle of π / 4.

5. The laser measuring device according to claim 1, characterized in that, The concave lens can be replaced with a concave lens with a different focal length to achieve measurements in different ranges.

6. The laser measuring device according to claim 1, characterized in that, The display panel has a scale, and the display panel can be rotated in a plane around its center point.

7. The laser measuring device according to any one of claims 1 to 6, characterized in that, It also includes data processing software configured to automatically calculate parallelism, perpendicularity, and concentricity based on the input sample size parameters and the data collected from the display panel.

8. A laser measurement method for detecting the shape error of a precision sample, using the laser measurement device according to any one of claims 1 to 7, characterized in that, include: The sample is fixed in the sample clamping device; The sample is rotated about its central axis using the sample clamping device. The polarized laser is directed to the surface of the sample through the beam splitter and the quarter glass slide; The light reflected from the sample surface is received, and the reflected light reaches the display panel via the beam splitter and the concave lens to form a light pattern. Observe and measure the size of the light pattern; as well as The shape error parameters of the sample are calculated based on the measured dimensions.

9. The laser measurement method according to claim 8, characterized in that, The shape error parameter is perpendicularity, and the method further includes: As the sample rotates, a circular aperture is observed to form on the display panel. Measure the radius of the circular aperture; and The perpendicularity is calculated based on the radius of the circular aperture, the magnification of the concave lens, and the optical path distance.

10. The laser measurement method according to claim 8 or 9, characterized in that, The shape error parameter is parallelism, and the method further includes: With the first side of the sample facing upwards, measure the first radius of the first circular aperture formed on the display panel; Flip the sample so that its second side is facing up and re-clamp it in the center; While the sample rotates, the second radius of the second circular aperture formed on the display panel is measured; and The parallelism is calculated based on the first radius and the second radius.

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