A non-contact optical measuring device for the depth-to-diameter ratio of micropores

Abstract

This utility model discloses a non-contact optical measurement device for the depth-to-diameter ratio of a micro-hole, including a measuring stage and a triaxial displacement stage placed on the measuring stage for fixing the workpiece; a hole depth measuring device and a hole diameter measuring device are also provided above the triaxial displacement stage; the hole depth measuring device includes a laser source, a first microscope objective, a beam splitter, a reflector, a camera lens, and a first CMOS camera. The hole depth H for calculating the depth-to-diameter ratio is determined by the difference in object distance corresponding to clear images of the bottom of the micro-hole and the surface of the workpiece by the first CMOS camera; the hole diameter measuring device includes a second CMOS camera, a third microscope objective, and a microscope tube connecting the second CMOS camera and the third microscope objective. The hole diameter D for calculating the depth-to-diameter ratio is determined by the difference between the micro-hole size in the image captured by the third microscope objective and the magnification of the third microscope objective. This device achieves rapid and accurate measurement of the depth-to-diameter ratio of a micro-hole at a low cost, facilitating its widespread use in industrial production and scientific research.

Description

Technical Field

[0001] This utility model relates to the field of optical measurement technology, and in particular to a non-contact optical measurement device for the depth-to-diameter ratio of a micro-aperture. Background Technology

[0002] In the field of precision manufacturing, high aspect ratio micro-hole structures are widely used in key technology areas such as micro-energy systems, photonic crystal devices, national defense and security, and aerospace due to their unique performance advantages. The aspect ratio parameter of microstructures directly affects the physicochemical properties, processing accuracy, and circuit performance of devices. Therefore, achieving accurate measurement of the micro-hole aspect ratio is of great significance for improving device performance and quality control.

[0003] Existing technologies for micro-orifice measurement are divided into two methods: contact measurement and non-contact measurement. Contact measurement requires destroying the structure of the micro-orifice, using a high-magnification optical microscope or scanning electron microscope after axially dissecting the micro-orifice. This method offers high accuracy but is also costly, and its applicability is limited due to the need to destroy the micro-orifice structure. Non-contact measurement, using traditional economical contact tools such as micrometers and plug gauges, is not only inefficient but can also scratch the surface of high-value workpieces. Currently, non-contact measurement is typically achieved using high-end optical measurement equipment (such as laser interferometers, spectral confocal systems, and optical frequency comb ranging). While offering excellent accuracy, these methods are expensive and cannot be widely adopted in industrial production and scientific research. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art, and proposes a non-contact optical measurement device for the micro-aperture depth-to-diameter ratio, which can achieve rapid and accurate measurement of the micro-aperture depth-to-diameter ratio at a lower cost and is easy to promote and use in industrial production and scientific research.

[0005] The present invention adopts the following technical solution: a non-contact optical measuring device for micro-hole depth-to-diameter ratio, comprising a measuring stage and a three-axis displacement stage placed on the measuring stage for fixing the workpiece; a hole depth measuring device and a hole diameter measuring device are also provided above the three-axis displacement stage;

[0006] The hole depth measuring device includes a laser source, a first microscope objective, a beam splitter, a reflector, a camera lens, and a first CMOS camera. The first microscope objective, beam splitter, and reflector are arranged vertically from low to high. The beam splitter is used to allow the laser beam emitted by the laser source to be emitted to the micro-hole of the workpiece through the first microscope objective. The reflector is used to reflect the reflected laser beam from the workpiece to the camera lens used in conjunction with the first CMOS camera. The hole depth H of the micro-hole is determined by the difference in object distance when the bottom of the micro-hole and the surface of the workpiece are clearly imaged by the first CMOS camera.

[0007] The aperture measurement device includes a second CMOS camera, a third microscope objective, and a microscope tube connecting the second CMOS camera and the third microscope objective. The aperture diameter D of the micropore is determined by the difference between the micropore size in the image captured by the third microscope objective and the magnification of the third microscope objective.

[0008] In some preferred embodiments, a second microscope objective is provided between the reflector and the camera lens.

[0009] In some preferred embodiments, the laser source has a working power of 10mw and generates a laser wavelength of 650nm; the first and second microscope objectives are both infinity-corrected flat-field microscope objectives with a magnification of 10x and a numerical aperture of 0.25.

[0010] In some preferred embodiments, the beam splitter is a 50:50 visible light beam splitter with a beam-splitting film on the front surface and an anti-reflection film on the rear surface.

[0011] In some preferred embodiments, the reflector is a metal film reflector.

[0012] In some preferred embodiments, one or more supplementary lights are provided above the three-axis displacement stage.

[0013] In some preferred embodiments, the supplemental light is an LED light module with a power of 1W and a color temperature of 6000K.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention uses an optical method to measure the depth H of a microhole on a workpiece using a hole depth measuring device, and uses an optical method to measure the diameter D of a microhole on a workpiece using a hole diameter measuring device, thereby accurately measuring the depth-to-diameter ratio of the microhole in a relatively simple measurement method.

[0016] In addition, this utility model adopts a modular design for both the hole depth measurement device and the hole diameter measurement device. The selected components are common and affordable products on the market, resulting in low cost. By optimizing the optical path structure, it has high practicality and operability while ensuring performance. It can achieve rapid and accurate measurement of the depth-to-diameter ratio of micro-holes at a low cost, which is convenient for widespread use in industrial production and scientific research. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical measuring device disclosed in this application;

[0018] Figure 2 This is a schematic diagram of the light reflection path of the hole depth measuring device;

[0019] Figure 3This is a schematic diagram of the light reflection path of the aperture measuring device. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by this application to achieve its intended purpose, the specific implementation methods, structures, features, and effects according to this application are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0021] This application proposes a non-contact optical measurement device for the depth-to-diameter ratio of micro-holes, which aims to achieve rapid and accurate measurement of the depth-to-diameter ratio of micro-holes at a low cost, facilitating its widespread use in industrial production and scientific research.

[0022] The micropores referred to in this application have a pore diameter not exceeding 0.5 mm and an aspect ratio greater than 3. For example, the pore diameter of the micropores is 0.1-0.3 mm and the aspect ratio is 3-10.

[0023] like Figure 1 As shown, the optical measuring device of this application includes a measuring stage 1, a three-axis displacement stage 2, a hole depth measuring device 4, and a hole diameter measuring device 5. The three-axis displacement stage 2 is placed on the measuring stage 1, and the workpiece 3 to be measured is placed on the three-axis displacement stage 2. The three-axis displacement stage 2 can drive the workpiece 3 to move precisely in the X-axis, Y-axis, or Z-axis as needed, thereby adjusting the optical detection distance between the workpiece 3 and the hole depth measuring device 4 or the hole diameter measuring device 5. The hole depth measuring device 4 and the hole diameter measuring device 5 are both fixed above the three-axis displacement stage 2. The hole depth measuring device 4 is used to measure the hole depth of the micro-hole on the workpiece 3 by optical means, while the hole diameter measuring device 5 is used to measure the hole diameter of the micro-hole on the workpiece 3 by optical means.

[0024] The three-axis displacement stage 2 uses a product currently available on the market, and its specific structure will not be described in detail here. Both the hole depth measuring device 4 and the hole diameter measuring device 5 can be fixed above the measuring stage 1 by existing means such as brackets, so the distance between the hole depth measuring device 4 or the hole diameter measuring device 5 and the measuring stage 1 remains unchanged.

[0025] The three-axis displacement stage 2 is located between the measuring stage 1 and the hole depth measuring device 4 or the hole diameter measuring device 5. When the hole depth measuring device 4 and the hole diameter measuring device 5 are used to measure the hole depth and hole diameter of the micro hole on the workpiece 3 respectively, the optical distance required for measurement between the workpiece 3 and the hole depth measuring device 4 or the hole diameter measuring device 5 is adjusted by the three-axis displacement stage 2.

[0026] This application balances the contradiction between measurement accuracy, economy, and measurement speed. The hole depth measuring device 4 and the hole diameter measuring device 5 are designed in a modular manner. The selected components are common and affordable products on the market. By optimizing the optical path structure, it has high practicality and operability while ensuring performance.

[0027] Combination Figure 2 As shown, the hole depth measuring device 4 specifically includes a laser source 41, a first microscope objective 42, a beam splitter 43, a reflector 44, a camera lens 46, and a first CMOS camera 47. The first microscope objective 42, beam splitter 43, and reflector 44 are arranged sequentially from low to high in the vertical direction (Z-axis). The beam splitter 43 is mainly used to change the propagation direction of the laser beam emitted by the laser source 41, so that the laser beam emitted by the laser source 41 can be emitted into the micro-hole of the workpiece 3 through the first microscope objective 42; the first microscope objective 42 is mainly used to form a reflected laser beam that magnifies the micro-hole after the laser beam emitted to the workpiece 3 is reflected back; and the reflector 44 is used to change the propagation path of the reflected laser beam again, reflecting the reflected laser beam to the camera lens 46, where it is imaged in the first CMOS camera 47 used in conjunction with the camera lens 46.

[0028] If the magnification of the first microscope objective 42 is insufficient, or if the first microscope objective 42 uses a low-magnification product with relatively low cost, a second microscope objective 45 can be added between the reflector 44 and the camera lens 46. The second microscope objective 45 is used to further magnify the reflected laser beam so that the micro-hole features can be reflected more clearly after the first CMOS camera 47 images the image.

[0029] In this example: the laser source 41 has a working power of 10mw and generates a laser wavelength of 650nm; the first microscope objective 42 and the second microscope objective 45 are both infinity-corrected flat-field microscope objectives with a magnification of 10x and a numerical aperture of 0.25; the beam splitter 43 is a 50:50 visible light beam splitter with a beam-splitting film on the front surface and an anti-reflection film on the rear surface; the reflector 44 is a metal film reflector; the camera lens 46 is a 25mm fixed-focus lens; and the first CMOS camera 47 is a monochrome camera with a 1 / 2.9-inch target surface.

[0030] During measurement, the laser beam output from the laser source 41 is reflected by the beam splitter 43 to the first microscope objective 42. The laser beam is then irradiated onto the surface of the workpiece 3 by the first microscope objective 42. The laser beam is then reflected back to the first microscope objective 42 by the surface of the workpiece 3. After being transmitted through the beam splitter 43, it reaches the reflecting mirror 44. The reflecting mirror 44 reflects the laser beam to the second microscope objective 45. Finally, it passes through the second microscope objective 45 and the camera lens 46 to reach the first CMOS camera 47.

[0031] Since the hole depth measuring device 4 is fixed above the measuring stage 1 and cannot be moved, while the workpiece 3 is placed on the three-axis displacement stage 2, the height in the vertical direction (Z-axis) can be adjusted by the three-axis displacement stage 2, thereby changing the object distance h between the workpiece 3 and the first microscope objective 42.

[0032] The object distance h determines whether the micro-aperture feature of workpiece 3 can be clearly imaged in the first microscope objective 42, which in turn determines whether a clear image can be observed in the first CMOS camera 47. A clear image can only be formed when the Gaussian imaging theorem is satisfied during micro-aperture focusing, that is, when the micro-aperture of workpiece 3 to be imaged is at the focal point of the first microscope objective 42.

[0033] As is well known, the first CMOS camera 47 has a built-in sharpness menu that reflects the clarity of image details. The sharpness characteristics of the image can be used to determine whether the imaging target is in focus. Therefore, by observing the sharpness changes of the image of the micro-aperture of workpiece 3 through the first CMOS camera 47: when the micro-aperture is in focus, the Gaussian imaging theorem is satisfied, and the image of the micro-aperture of workpiece 3 observed by the first CMOS camera 47 has the best clarity, corresponding to a sharpness peak. However, when the micro-aperture of workpiece 3 is out of focus, the image becomes a blurry spot, causing the image received by the first CMOS camera 47 to become blurred, resulting in a lower sharpness value. Therefore, when the sharpness of the image is at its peak, it can be determined that the object distance h between workpiece 3 and the first microscope objective 42 is exactly at the imaging focus.

[0034] When measuring the depth of the micro-hole of the workpiece 3 using the hole depth measuring device 4, it is only necessary to adjust the object distance h between the micro-hole of the workpiece 3 and the first microscope objective 42 through the three-axis displacement stage 2. The object distance h1 when the first microscope objective 42 focuses on the bottom of the micro-hole and the object distance h2 when the first microscope objective 42 focuses on the surface of the workpiece 3 (corresponding to the top surface of the micro-hole) are determined respectively. The difference h1-h2 between the object distances when the bottom of the micro-hole and the surface of the workpiece are clearly imaged by the first CMOS camera is determined as the depth of the micro-hole H, that is, the depth of the micro-hole H=h1-h2.

[0035] That is, when the first microscope objective 42 images the bottom of the micro-hole, the object distance h between the micro-hole of the workpiece 3 and the first microscope objective 42 is adjusted by the triaxial stage 2. When the image is observed to be at its sharpness peak by the first CMOS camera 47, the Z-axis height m1 of the workpiece 3 on the triaxial stage 2 is recorded. This m1 corresponds to the object distance h1. Similarly, when the first microscope objective 42 images the surface of the workpiece 3, when the image is observed to be at its sharpness peak by the first CMOS camera 47, the Z-axis height m2 of the workpiece 3 on the triaxial stage 2 is recorded. This m2 corresponds to the object distance h2. Therefore, m1 - m2 = H = h1 - h2, thus accurately determining the depth H of the micro-hole.

[0036] Further integration Figure 3 As shown, the aperture measuring device 5 includes a second CMOS camera 51, a third microscope objective 52, and a microscope tube 53 connecting the second CMOS camera 51 and the third microscope objective 52. The third microscope objective 52 images the surface of the micro-hole of the workpiece 3 into the second CMOS camera 51. Similarly, the sharpness change of the image captured by the second CMOS camera 51 can be used to determine whether the object distance between the workpiece 3 and the third microscope objective 52 is at the focal point.

[0037] For example, if the third microscope objective 52 and the first microscope objective 52 are of the same specifications, when the depth of the micro-hole of the workpiece 3 is measured by the hole depth measuring device 4, the object distance h2 when the first microscope objective 42 focuses on the surface of the workpiece 3 is determined. At this time, when the workpiece 3 is moved from directly below the hole depth measuring device 4 to directly below the aperture measuring device 5 by moving the three-axis displacement stage 2 along the X-axis or Y-axis, it is exactly the focusing position between the surface of the workpiece 3 and the second CMOS camera 51. This simplifies the operation and reduces the need for further focusing when measuring with the aperture measuring device 5.

[0038] In addition, to make the imaging of the micro-hole surface of the workpiece 3 by the aperture measuring device 5 clearer, one or more supplementary lights (not shown in the figure) can be set above the three-axis displacement stage 2. The supplementary lights can be conventional LED lights, such as LED light modules with a power of 1W and a color temperature of 6000K.

[0039] For example, if the third microscope objective 52 is a finite-distance microscope objective with a magnification of 10x, that is, the third microscope objective 52 magnifies the micro-aperture by 10x. In the image captured by the second CMOS camera 51, the pixel size occupied by the micro-aperture is determined using the CMOS camera's built-in software or existing image processing algorithms. Then, by dividing by the magnification of the third microscope objective 52, the aperture D of the micro-aperture can be accurately determined.

[0040] For example, the process of determining the pixel size occupied by the micro-aperture in the image captured by the second CMOS camera 51 using existing technology is as follows: First, the image is preprocessed using a Gaussian blur algorithm. Then, the edge contour of the aperture is extracted using a Cannoy edge detection algorithm. After extraction, a Hough circle transform algorithm is used to fit the circle to the edge contour. Finally, the pixel diameter of the micro-aperture in the image can be obtained. Since the optical magnification of the device is 10 times, and the size of a single pixel in the image captured by the second CMOS sensor 51 is known, the actual aperture diameter D of the micro-aperture can be calculated.

[0041] As can be seen from the above description, the micro-hole depth H of the workpiece 3 can be accurately measured by the hole depth measuring device 4, and the micro-hole diameter D of the workpiece 3 can be accurately measured by the hole diameter measuring device 5. The micro-hole depth-to-diameter ratio x=H / D can be directly calculated.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A non-contact optical measuring device for micro-aperture aspect ratio, comprising a measuring stage and a triaxial displacement stage placed on the measuring stage for fixing the workpiece; characterized in that, A hole depth measuring device and a hole diameter measuring device are also installed above the three-axis displacement stage; The hole depth measuring device includes a laser source, a first microscope objective, a beam splitter, a reflector, a camera lens, and a first CMOS camera. The first microscope objective, beam splitter, and reflector are arranged vertically from low to high. The beam splitter is used to allow the laser beam emitted by the laser source to be emitted to the micro-hole of the workpiece through the first microscope objective. The reflector is used to reflect the reflected laser beam from the workpiece to the camera lens used in conjunction with the first CMOS camera. The hole depth H of the micro-hole is determined by the difference in object distance when the bottom of the micro-hole and the surface of the workpiece are clearly imaged by the first CMOS camera. The aperture measurement device includes a second CMOS camera, a third microscope objective, and a microscope tube connecting the second CMOS camera and the third microscope objective. The aperture diameter D of the micropore is determined by the difference between the micropore size in the image captured by the third microscope objective and the magnification of the third microscope objective.

2. The non-contact optical measuring device according to claim 1, characterized in that, A second microscope objective is provided between the reflector and the camera lens.

3. The non-contact optical measuring device according to claim 2, characterized in that, The laser source has a working power of 10mw and produces a laser wavelength of 650nm; the first and second microscope objectives are both infinity-corrected flat-field microscope objectives with a magnification of 10x and a numerical aperture of 0.

25.

4. The non-contact optical measuring device according to claim 1, characterized in that, The beam splitter is a 50:50 visible light beam splitter with a beam-splitting film on the front surface and an anti-reflection film on the rear surface.

5. The non-contact optical measuring device according to claim 1, characterized in that, The reflector is a metal film reflector.

6. The non-contact optical measuring device according to any one of claims 1-5, characterized in that, One or more supplementary lights are installed above the three-axis displacement stage.

7. The non-contact optical measuring device according to claim 6, characterized in that, The supplemental light is a 1W LED module with a color temperature of 6000K.

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