A blind hole depth-diameter ratio measuring device based on white light microscopic interference method

Abstract

The utility model relates to a blind hole measuring technical field, specifically is a kind of blind hole depth-diameter ratio measuring device based on white light microscopic interference method, including workbench and the workbench upper end middle part setting can be the beam splitter of incident light refraction as two, the workbench upper end is sequentially provided with the light source assembly of the outside of beam splitter, sample placement assembly, reflector and acquisition component;The utility model emits white light source by light source assembly and is refracted to reflector and sample placement assembly at beam splitter, and interference fringes are generated above beam splitter by the light line of cooperation interference objective lens reflected back, then image information is collected by acquisition piece and is converted into digital signal output to the computer set in the placement platform, then image processing is carried out by computer, to carry out the measurement and calculation of the relevant data of blind hole depth-diameter ratio.

Description

Technical Field

[0001] This utility model relates to the field of blind hole measurement technology, specifically a blind hole depth-to-diameter ratio measuring device based on white light micro-interference method. Background Technology

[0002] With the rapid development of the micro-nano manufacturing and precision machining industry, micro-holes, as key structures, have been widely used in critical fields such as aerospace, semiconductor packaging, and microfluidic chips. These applications place strict requirements on the aspect ratio (the ratio of depth to diameter) of microstructures. In particular, when the diameter of the microhole is in the range of 0.1-0.3mm and the aspect ratio reaches 3-10, which is the range of "large aspect ratio blind holes", its dimensional accuracy directly affects the heat dissipation efficiency, conductivity, and structural stability of the product. Therefore, achieving high-precision measurement of such microhole parameters has become a core link and primary requirement for ensuring product quality.

[0003] Traditional measurement methods are mostly contact-based, which can easily cause physical damage or impurity residue to the sample surface and the interior of blind holes, leading to excessive measurement errors. Existing non-contact optical measurement methods partially rely on monochromatic laser interference, but the repetitive laser fringes can easily cause phase ambiguity. Furthermore, when measuring blind holes with aspect ratios of 3-10, they are susceptible to edge blurring and poor repeatability due to light attenuation, and their measurement efficiency is low, making it difficult to meet the requirements for high-precision, rapid, and non-destructive measurement. Therefore, this invention provides a non-contact, high-efficiency white light micro-interference method for measuring the depth-to-diameter ratio of blind holes. Utility Model Content

[0004] To address the problems of contact measurement in existing technologies that easily damage samples and lead to increased measurement errors, a blind hole depth-to-diameter ratio measuring device based on white light micro-interference method was designed.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a blind hole depth-to-diameter ratio measuring device based on white light micro-interference method, including a worktable and a beam splitter set in the middle of the upper part of the worktable, which can refract incident light into two beams. The upper part of the worktable is sequentially provided with a light source assembly, a sample placement assembly, a reflector and a collection assembly located outside the beam splitter, and the adjacent two assemblies are spaced 90° apart. The light source assembly includes an aperture stop for controlling the diameter of the incident light to ensure that the light can enter the bottom of the blind hole; the sample placement assembly includes a converging lens for converging the light reflected from the sample so that it can be captured by the acquisition assembly; and the acquisition assembly includes an interference objective for focusing the light onto the sample surface and generating interference.

[0006] Furthermore, the light source assembly also includes a light source element and a collimating lens, which are sequentially arranged on both sides of the aperture stop. The light source element is used to generate broadband white light, and the collimating lens can collimate the diverging light source into parallel light rays to ensure the uniformity of the light beam.

[0007] Furthermore, the sample placement assembly also includes a sample placement stage equipped with a clamp. The sample placement stage is located on the side of the converging lens away from the beam splitter. The sample placement assembly and the acquisition assembly are on the same horizontal line, used to fix the sample and can drive the sample to move radially along the interference objective.

[0008] Furthermore, the acquisition component also includes an acquisition element for capturing the interference image and converting it into a digital signal output, the acquisition element being located on the side of the interference objective lens away from the beam splitter.

[0009] Furthermore, the beam splitter, reflector, light source assembly, sample placement assembly, and acquisition assembly are all equipped with height-adjustable support assemblies at their bottoms. The reflector serves as a reference surface and can reflect light back to the beam splitter.

[0010] Furthermore, protective components are fixedly connected around the upper part of the worktable to block external airflow and prevent airflow disturbance from interfering with the optical path. A placement platform is fixedly connected to one side of the worktable to place a computer and connect it to the acquisition device via a line to receive the digital signals output by the acquisition device and perform image analysis processing to calculate the blind hole depth-to-diameter ratio.

[0011] The beneficial effects of this utility model are: This invention emits white light from a light source assembly, which is refracted by a beam splitter to a reflector and a sample placement assembly. The reflected light, in conjunction with an interference lens, generates interference fringes above the beam splitter. Image information is then acquired by a data acquisition unit and converted into digital signals, which are output to a computer located on the placement platform. The computer then performs image processing to measure and calculate the depth-to-diameter ratio of the blind hole. By performing tomographic image analysis on the acquired interference fringe image and combining it with two-dimensional Gaussian fitting, non-contact optical non-destructive measurement is performed. This method enables efficient and high-precision measurement of the depth and diameter of blind holes, is easy to operate, and offers high precision and efficiency. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is a schematic diagram of the main structure of this utility model; Figure 2 This is a schematic diagram of the main body side structure of this utility model; Figure 3 This is a schematic diagram of the internal structure of the workbench of this utility model; Figure 4 For the present utility model Figure 3 A magnified view of part A; Figure 5 This is a top view of the main structure of this utility model; Figure 6 This is a partial sectional view of the workbench of this utility model; Figure 7 For the present utility model Figure 6 A partially enlarged sectional view at point B; Figure 8 This is a schematic diagram illustrating the technical principle of the white light micro-interference measurement method of this utility model. Figure 9 This is a tomographic image rendering of the tomographic image analysis method of this utility model; Figure 10 This is a tomographic image contour diagram of the tomographic image analysis method of this utility model; Figure 11 This is a two-dimensional Gaussian fitting hole surface data diagram of the two-dimensional Gaussian fitting method of this utility model; Figure 12 This is a diagram showing the calculation of the diameter using the two-dimensional Gaussian fitting method of this invention.

[0014] In the figure: 1. Worktable; 2. Protective component; 3. Support assembly; 4. Beam splitter; 5. Light source assembly; 51. Light source component; 52. Aperture stop; 53. Collimating lens; 6. Reflector; 7. Sample placement assembly; 71. Sample placement stage; 72. Converging lens; 8. Acquisition assembly; 81. Acquisition component; 82. Interference objective lens; 9. Placement platform. Detailed Implementation

[0015] To make the technical means, technical features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0016] Example: Figure 1 - Figure 7 As shown, the blind aperture depth-to-diameter ratio measuring device based on white light micro-interference method of this utility model includes a worktable 1 and a beam splitter 4 set at the middle of the upper end of the worktable 1, which can refract incident light into two beams. The upper end of the worktable 1 is sequentially arranged with a light source assembly 5, a sample placement assembly 7, a reflector 6 and a collection assembly 8 located outside the beam splitter 4, and the adjacent two assemblies are spaced 90° apart. The light source assembly 5 includes an aperture stop 52 for controlling the diameter of the incident light to ensure that the light can enter the bottom of the blind aperture. The sample placement assembly 7 includes a converging lens 72 for converging the light reflected from the sample so that it can be captured by the collection assembly 8. The collection assembly 8 includes an interference objective lens 82 for focusing the light to the sample surface and generating interference.

[0017] Specifically, the light source assembly 5, sample placement assembly 7, reflector 6, and acquisition assembly 8 are arranged around the outer perimeter of the beam splitter 4. The light source assembly 5 is spaced 90° apart from the sample placement assembly 7 and the acquisition assembly 8, the sample placement assembly 7 is spaced 90° apart from the reflector 6, and the reflector 6 is spaced 90° apart from the acquisition assembly 8. The light source assembly 5 outputs light to the beam splitter 4. The light output from the light source assembly 5 is refracted into two beams and sent to the sample placement assembly 7 and the reflector 6 respectively. The sample placement assembly 7 is used to place the sample to be tested and converges the light reflected from the sample surface to the beam splitter 4 through the converging lens 72 to generate interference fringes. At the same time, the reflector 6 reflects the light to the beam splitter 4 to generate interference fringes. Image data is acquired through the acquisition assembly 81. The white light micro-interference measurement method uses white light interference to generate interference fringes. Since the optical path difference of each band is zero at the zero-order fringe, the light intensity is strongest at the zero-order fringe, which can be used as a reference point for depth measurement.

[0018] In this embodiment, the light source assembly 5 further includes a light source element 51 and a collimating lens 53. The light source element 51 and the collimating lens 53 are sequentially arranged on both sides of the aperture stop 52. Specifically, as shown... Figure 3 As shown, the light source 51 is used to generate broadband white light as the basis for interference. After passing through the beam splitter 4, the white light source forms two beams. The aperture stop 52 can adjust the diameter of the broadband white light output by the light source 51 to match the bottom aperture of the blind hole, so that the light can accurately enter the blind hole. The collimating lens 53 can collimate the divergent light source into parallel light, ensuring that the beam is uniform. The white light emitted by the light source 51 is a composite light generated by mixing multicolor light or exciting special materials through different technical means. Specifically, it can be generated by artificial light source technology or natural light source and physical phenomena.

[0019] In this embodiment, the sample placement assembly 7 further includes a sample placement stage 71 with a clamp. The sample placement stage 71 is located on the side of the converging lens 72 away from the beam splitter 4. The sample placement assembly 7 and the acquisition assembly 8 are on the same horizontal line, used to fix the sample and can drive the sample to move radially along the interference objective lens 82.

[0020] Specifically, such as Figure 3 and Figure 4As shown, the sample stage 71 is equipped with a central clamp, which can be configured to clamp and fix the sample to be tested by moving two sets of clamping blocks through a motor-driven bidirectional lead screw, while correcting the perpendicularity of the sample and reducing the influence of tilt on the interference image. The clamp can also be any other mechanism that can achieve the same effect. At the same time, the sample stage 71 is slidably connected to the support assembly 3 at the bottom, which can move the sample radially along the interference objective lens 82. The purpose is to make the light hit the surface of the sample stage. The interference fringe image at this moment is acquired by the acquisition device 81 and sent to the computer. Then, the sample stage 71 continues to move radially along the interference objective lens 82. The acquisition device 81 acquires images multiple times during this process to obtain the interference fringe image generated when the focused light hits the bottom of the blind hole. The image is then sent to the computer for image analysis and the depth-to-diameter ratio of the blind hole is calculated. The distance from the sample stage 71 to the beam splitter 4 is equal to or slightly greater than the distance from the reflector 6 to the beam splitter 4.

[0021] In this embodiment, the acquisition component 8 also includes an acquisition element 81 for capturing interference images and converting them into digital signal outputs. The acquisition element 81 is located on the side of the interference objective lens 82 away from the beam splitter 4. The beam splitter 4, the reflector 6, the light source assembly 5, the sample placement assembly 7, and the bottom of the acquisition component 8 are all provided with adjustable height support assemblies 3. The reflector 6 serves as a reference surface and can reflect light back to the beam splitter 4.

[0022] Specifically, such as Figure 1 - Figure 7 As shown, the acquisition component 81 can be configured as a CCD camera to capture interference fringe images in real time and transmit them to a computer. At the same time, the acquisition component 81 can also be configured as other devices that can achieve the same effect. The support assembly 3 can be configured to use an electro-hydraulic push rod and a push plate to push the push plate and cooperate with the laser collimator for optical path adjustment. By adjusting the height of the internal structure of each component, the corresponding optical axes of each component are ensured to be collinear. Specifically, the light source assembly 5, the beam splitter 4 and the reflector 6 keep their optical axes collinear, and the sample placement assembly 7, the beam splitter 4 and the acquisition assembly 8 keep their optical axes collinear. At the same time, the support assembly 3 can also be configured as any other structure that can achieve the same effect.

[0023] In this embodiment, protective components 2 are fixedly connected around the upper perimeter of the workbench 1 to block external airflow and prevent airflow disturbance from interfering with the optical path. A placement platform 9 is fixedly connected to one side of the workbench 1. Specifically, as shown in the figure... Figure 1 and Figure 2As shown, the placement platform 9 is used to place the computer and connect it to the acquisition unit 81 via a line to receive the digital signals output by the acquisition unit 81 and perform image analysis processing to calculate the blind hole depth-to-diameter ratio. The protective component 2 can be set as a surrounding plate, distributed on the upper end of the worktable 1 to surround the processing area of ​​the device. At the same time, the protective component 2 can also be set as any other structure that can achieve the same effect. The attached figure does not represent the actual size of each component. During design and use, it can be adjusted according to the actual situation.

[0024] In this embodiment, as Figure 8-12 As shown, the core methods employed in this device are white light micro-interferometry measurement, tomographic image analysis, and two-dimensional Gaussian fitting. For ease of understanding, only the basic principles of these three methods are provided below: Firstly, there is the white light micro-interferometry measurement method. This method utilizes white light interference to generate interference fringes. Since the optical path difference is zero across all wavelengths at the zero-order fringe, the light intensity is strongest at the zero-order fringe, which can serve as a reference point for depth measurement. The basic principle is as follows: the white light source, after passing through beam splitter 4, forms two beams. One beam is directed towards the reference surface, and the other towards the measurement surface. When the distance from the reference surface to beam splitter 4 is equal to the distance from the measurement surface to beam splitter 4, interference fringes will be generated above beam splitter 4. The sample stage is moved along the axis of the interferometer objective 82, and the interference image at the corresponding scanning position is recorded by the image acquisition system. This determines the zero optical path difference position of the coherent light at different locations on the sample surface. Based on the correspondence between the zero optical path difference position and the height, the blind hole depth h is obtained. The technical principle of the white light micro-interferometry measurement method is as follows: Figure 8 As shown.

[0025] Secondly, tomographic image analysis is used. This involves vertical scanning of the three-dimensional image using white-light microinterferometry. The tomographic image is reconstructed from the focused image data of each pixel captured by the camera's CCD through a three-dimensional objective lens. The resulting image is shown in the figure below. Figure 9 As shown, further image algorithms are used for contour extraction, such as... Figure 10 As shown.

[0026] Finally, the two-dimensional Gaussian fitting method is used. However, due to light attenuation, noise may affect the three-dimensional data, blurring edges and reducing repeatability. Therefore, the tomographic image inside the aperture is converted into three-dimensional surface data, where the intensity of each pixel is displayed as height, such as... Figure 11 As shown, the transformed 3D surface shape resembles a 2D Gaussian curve; therefore, 2D Gaussian fitting is chosen for modeling. Figure 12 The diameter measurement results are displayed.

[0027] The above measurement method is only a basic, feasible summary. The steps of the above method are all existing technologies. Therefore, it can be refined in combination with existing technologies during implementation. This application will not elaborate further.

[0028] Working principle: First, fix the beam splitter 4, light source 51, aperture stop 52, collimating lens 53, reflecting mirror 6, sample stage 71, converging lens 72, acquisition unit 81 and interference objective lens 82 to the upper push plate of the support assembly 3. Then, adjust the optical path through the support assembly 3 with the laser collimator to ensure that the corresponding optical axes of each component are collinear, and connect the acquisition unit 81 to the computer. Next, the blind hole sample is fixed in the fixture on the sample placement stage 71. At the same time, the perpendicularity of the sample is corrected to reduce the influence of tilt on the interference image. The position of the sample is adjusted so that the distance from its surface to the beam splitter 4 is approximately equal to the distance from the reflecting mirror 6 to the beam splitter 4. Then, the sample placement stage 71 is moved radially along the interference objective lens 82 so that the light hits the sample surface. The interference fringe image at this moment is acquired using the acquisition device 81 and transmitted to the computer. Then, the sample placement stage 71 is moved radially along the interference objective lens 82, and the acquisition device 81 is used to acquire images in this process multiple times in order to obtain the interference fringe image generated when the focused light hits the bottom of the blind hole. The image is then transmitted to the computer. The computer CCD driver software converts the two interference fringe images acquired in the above steps into digital signals. Using the measured values ​​of light intensity, grayscale value, and optical path difference obtained by the driver software, the value of h is calculated using the following formula: h = (Optical path difference of upper surface - optical path difference of lower surface) / 2 Next, based on the tomographic image analysis method and the two-dimensional Gaussian fitting method, the measurement process of the blind hole diameter is as follows: First, the interference fringe image acquired by the acquisition device 81 in the above steps is imported into the Matlab program. The image is processed and analyzed using code, and converted into a simulated tomographic image. Then, the contour of the blind hole is extracted from the tomographic image using an edge detection algorithm. Then, the tomographic image inside the hole is converted into three-dimensional surface data, and two-dimensional Gaussian fitting is used for modeling to obtain the blind hole diameter data, thereby outputting the depth-to-diameter ratio result.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The descriptions of the above embodiments and specifications are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by this utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A blind aperture depth-to-diameter ratio measuring device based on white light microinterference, comprising a worktable and a beam splitter disposed at the center of the upper part of the worktable to refract incident light into two beams, characterized in that: The upper end of the worktable is sequentially provided with a light source assembly, a sample placement assembly, a reflector, and a collection assembly located outside the beam splitter, with adjacent assemblies spaced 90° apart. The light source assembly includes an aperture stop for controlling the diameter of the incident light to ensure that the light can enter the bottom of the blind hole; The sample placement assembly includes a converging lens for focusing the light reflected from the sample so that it can be captured by the acquisition assembly. mirror; The acquisition component includes an interference objective lens for focusing light onto the sample surface and generating interference.

2. The blind hole depth-to-diameter ratio measuring device based on white light microinterference as described in claim 1, characterized in that: The light source assembly also includes a light source element and a collimating lens, which are arranged sequentially on both sides of the aperture stop.

3. The blind hole depth-to-diameter ratio measuring device based on white light microinterference as described in claim 1, characterized in that: The sample placement assembly also includes a sample placement stage equipped with a clamp. The sample placement stage is located on the side of the converging lens away from the beam splitter, and the sample placement assembly and the acquisition assembly are on the same horizontal line.

4. The blind hole depth-to-diameter ratio measuring device based on white light microinterference as described in claim 3, characterized in that: The acquisition assembly also includes an acquisition element for capturing the interference image and converting it into a digital signal output, the acquisition element being located on the side of the interference objective lens away from the beam splitter.

5. The blind hole depth-to-diameter ratio measuring device based on white light microinterference as described in claim 4, characterized in that: The beam splitter, reflector, light source assembly, sample placement assembly, and acquisition assembly are all equipped with height-adjustable support assemblies at their bottoms. The reflector serves as a reference surface and can reflect light back to the beam splitter.

6. The blind hole depth-to-diameter ratio measuring device based on white light microinterference as described in claim 1, characterized in that: The upper part of the workbench is fixedly connected with protective components around its perimeter, and a placement platform is fixedly connected to one side of the workbench for placing a computer and connecting it to the data acquisition device via a cable.

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