Optical 3D micro-nano depth detection system

Abstract

The invention discloses an optical 3D micro-nano depth detection system, and belongs to the technical field of nondestructive testing, a light source module is used for respectively generating and emitting a sample arm light beam and a reference arm light beam, and an optical fiber circulator is connected with the light source module. The scanning module comprises a scanning module and a two-axis galvanometer, the two-axis galvanometer comprises a first port and a second port, light beams of the first port and the second port can be transmitted mutually, the first port corresponds to the optical fiber circulator, and the axis of the second port is perpendicular to the PCB. The detection coupling module receives the reference arm light beam and the return light beam at the same time, interference of the return light beam and the reference arm light beam is formed, an interference signal is generated, and three-dimensional data of the hole is generated through the interference signal. The optical 3D micro-nano depth detection system provided by the invention not only can realize comprehensive and accurate detection of hole inner wall images such as deep micropores, but also can ensure the detection efficiency of in-hole detection on a PCB (Printed Circuit Board), and the detection cost is remarkably reduced while the detection precision is ensured and the detection efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the field of non-destructive testing technology, and in particular relates to an optical 3D micro-nano depth detection system. Background Art

[0002] In recent years, with the miniaturization of consumer electronic devices and the popularization of high-frequency communication technology, PCB boards, as one of the key components of electronic devices, have not only gradually become smaller in size with the rapid development of related technologies, but the number of optoelectronic components required to be integrated in PCB boards and the density of PCB holes have also gradually increased. In particular, when the PCB hole diameter gradually shrinks to below 50μm, the hole density will increase to hundreds per square centimeter. At the same time, in order to ensure the quality of PCB boards, each hole on the PCB board needs to be accurately inspected during the production and preparation process of PCB boards.

[0003] In related technologies, optical inspection, X-ray inspection, and contact probe inspection are commonly used to inspect holes on PCB boards. However, these three inspection methods often have certain drawbacks, as follows: Optical inspection mainly relies on collecting in-hole image information to detect the status inside the hole. The two-dimensional image analysis it relies on is usually unable to identify three-dimensional defects such as cracks and voids in the coating on the inner wall of the hole. The false detection rate is high, usually at 15% to 20%.

[0004] X-ray inspection equipment is expensive and has insufficient resolution for microvias, making it difficult to meet the inspection requirements of high-end HDI boards (High Density Interconnect).

[0005] Contact probe detection can easily damage the plating inside the hole, and the detection speed is lower than 10 holes / second, which can easily form a bottleneck in mass production. Summary of the Invention

[0006] In response to one or more of the above-mentioned defects or improvement needs in the prior art, the present invention provides an optical 3D micro-nano depth detection system, which can adapt to the small aperture and dense distribution characteristics of PCB boards. It can not only realize comprehensive and accurate detection of the inner wall images of holes such as deep microholes, but also ensure the detection efficiency of in-hole detection on PCB boards, significantly reducing the detection cost while ensuring detection accuracy and improving detection efficiency.

[0007] To achieve the above objectives, the present invention provides an optical 3D micro-nano depth detection system for detecting holes on PCB boards, comprising: A light source module, the light source module is used to generate and emit a sample arm beam and a reference arm beam with the same frequency, constant phase difference and the same polarization direction; A fiber optic circulator, wherein a first optical path is provided between the fiber optic circulator and the light source module, for receiving the sample arm light beam; A scanning module, comprising a scanning module and a two-axis galvanometer; the two-axis galvanometer comprises a first port and a second port through which light beams can be transmitted to each other, the first port being connected to the fiber optic circulator for entry of the sample arm light beam; a scanning module being provided on the second port, the scanning module being aligned with the PCB board and for emitting the sample arm light beam onto the PCB board; the sample arm light beam is irradiated onto the PCB board and forms a return light beam, which sequentially passes through the scanning module, the second port, and the first port into the fiber optic circulator; A detection coupling module is provided, wherein a second optical path is provided between the detection coupling module and the light source module, and a third optical path is provided between the detection coupling module and the fiber circulator, so that the detection coupling module simultaneously receives the reference arm beam and the return beam, and the reference arm beam and the return beam form interference in the detection coupling module to generate an interference signal, and the detection coupling module generates three-dimensional data of the hole according to the interference signal.

[0008] As a further preferred embodiment of the present invention, the light source module includes a swept laser, which adapts to the transmission spectrum characteristics of the PCB board to provide an initial light beam, so that the K-clock signal of the initial light beam can generate a sampling trigger clock.

[0009] As a further preferred embodiment of the present invention, the bandwidth of the swept laser is 100 nm, the sweep speed is 400 kHz, and the wavelength of the initial light beam is 1060 nm.

[0010] As a further preferred embodiment of the present invention, the light source module further includes a splitter coupler, which receives the initial beam of the swept laser and splits it into a sample arm beam and a reference arm beam.

[0011] As a further preferred embodiment of the present invention, the intensity of the sample arm beam is not less than 80% and not more than 90%, the intensity of the reference arm beam is not less than 10% and not more than 20%, and the sum of the intensities of the two is 100%.

[0012] As a further preferred embodiment of the present invention, it further includes an optical fiber delay line, which receives the reference arm light beam and is used to introduce a time delay into the transmission of the reference arm light beam.

[0013] As a further preferred embodiment of the present invention, it further includes a polarization controller, which receives the reference arm light beam transmitted from the optical fiber delay line and changes the polarization state of the reference arm light beam.

[0014] As a further preferred embodiment of the present invention, the scanning module includes a high-precision galvanometer and a piezoelectric ceramic translation stage. The high-precision galvanometer is coaxial with the second port and is used to emit a sample arm beam or receive the return beam. The piezoelectric ceramic translation stage is fixedly connected to the high-precision galvanometer and is used to control the movement position of the high-precision galvanometer.

[0015] As a further preferred embodiment of the present invention, a fiber collimator is provided between the fiber circulator and the two-axis galvanometer, and the fiber collimator is used to adjust the parallelism of each light in the sample arm light beam.

[0016] As a further preferred embodiment of the present invention, the detection coupling module includes an interference coupler, a light detection module and a signal processing module. The interference coupler simultaneously receives the reference arm light beam and the return light beam, and interferes with the two to generate two interference signals. The light detection module receives the interference signal and converts the interference signal into an electrical signal. The signal processing module calculates the three-dimensional data of the hole based on the electrical signal.

[0017] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art: (1) The optical 3D micro-nano depth detection system of the present invention comprises a light source module for generating and emitting a sample arm beam and a reference arm beam respectively, and a fiber circulator connected to the light source module for receiving the sample arm beam. The scanning module comprises a scanning module and a two-axis galvanometer, the two-axis galvanometer comprising a first port and a second port through which light beams can be transmitted to each other, the first port corresponding to the fiber circulator for receiving the sample arm beam or refracting the return beam; the axis of the second port is perpendicular to the PCB board, and a scanning module is provided between the second port and the PCB board for emitting the sample arm beam onto the PCB board and collecting the return beam emitted from the PCB board. The detection coupling module simultaneously receives the reference arm beam and the return beam, forming interference between the return beam and the reference arm beam to generate an interference signal, and generates three-dimensional data of the hole through the interference signal. The detection system can adapt to the small aperture and dense distribution characteristics of the PCB board, and can not only realize comprehensive and accurate detection of the inner wall image of the hole, such as deep microholes, but also ensure the detection efficiency of the hole detection on the PCB board, while ensuring the detection accuracy and improving the detection efficiency, and significantly reducing the detection cost.

[0018] (2) The optical 3D micro-nano depth detection system of the present invention has accurate detection, high speed and good adaptability. It uses a sweeping laser with a sweeping rate of 400kHz and a 2Gsample / s acquisition card, combined with time-wavelength linearization technology, to compress the single-hole detection time to less than 10ms. In addition, the detection technology based on the coherent detection principle enables the detection system to detect deep microholes with a diameter of more than 30um and a depth-to-diameter ratio of 20:1. At the same time, the axial resolution is significantly improved by the ultra-wideband sweeping light source, thereby making the recognition accuracy of the detection results higher. Description of the drawings Figure 1 3D micro-nano depth detection system according to an embodiment of the present invention; In all the drawings, the same reference numerals represent the same technical features, specifically: 1. Sweep laser; 2. Splitting coupler; 3. Fiber delay line; 4. Polarization controller; 5. Fiber circulator; 6. Fiber collimator; 7. Two-axis galvanometer; 8. Scanning module; 9. PCB board; 10. Interference coupler; 11. Optical detection module; 12. Signal processing module. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0022] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0024] Example: See also Figure 1 The optical 3D micro-nano depth detection system in the preferred embodiment of the present invention can adapt to the small aperture and dense distribution characteristics of the PCB board 9. It can not only realize comprehensive and accurate detection of the inner wall images of holes such as deep micro-holes, but also ensure the detection efficiency of the holes on the PCB board 9, significantly reducing the detection cost while ensuring the detection accuracy and improving the detection efficiency.

[0025] Specifically, if Figure 1 As shown in , in a preferred embodiment of the present application, the optical 3D micro-nano depth detection system includes a light source module, an optical fiber circulator 5, a scanning module and a detection coupling module.

[0026] The light source module is used to generate and transmit a sample arm beam and a reference arm beam, respectively. The sample arm beam and the reference arm beam have the same frequency, a constant phase difference, and the same polarization direction, thereby providing a stable and accurate light source for testing the PCB board 9. The fiber optic circulator 5 is connected to the light source module via a first optical path to receive and transmit the sample arm beam or the return beam.

[0027] The scanning module is arranged on one side of the PCB board 9, which receives the sample arm beam and applies the sample arm beam to the PCB board 9 to form a scan of the PCB board 9. Specifically, the scanning module includes a scanning module 8 and a two-axis galvanometer 7, wherein the two-axis galvanometer 7 includes a first port and a second port through which light beams can be transmitted to each other. The first port is connected to the optical fiber circulator 5 and is used for the entry of the sample arm beam. The sample arm beam enters from the first port and is emitted from the second port. At the same time, a scanning module 8 is provided on the second port, and the scanning module 8 is aligned with the PCB board 9. The scanning module 8 is used to emit the sample arm beam onto the PCB board 9. The sample arm beam is irradiated on the PCB board 9 to form a return beam. At the same time, the return beam passes through the scanning module 8, the second port and the first port in sequence to enter the optical fiber circulator 5.

[0028] A second optical path is set between the detection coupling module and the light source module, and a third optical path is set between the detection coupling module and the optical fiber circulator 5, so that the detection coupling module receives the reference arm beam and the return beam at the same time, and the reference arm beam and the return beam form interference in the detection coupling module and generate an interference signal. The detection coupling module generates three-dimensional data of the hole based on the interference signal, and then uses the three-dimensional data in the hole to accurately and quickly analyze the internal quality of each hole.

[0029] Furthermore, in a preferred embodiment of the present application, the light source module includes a swept-frequency laser 1, which adapts to the transmission spectrum characteristics of the PCB board 9 to provide an initial light beam, which is used to generate a sampling trigger clock from the K-clock signal of the initial light beam. In actual use, the interference spectrum signal obtained by the photodetector in the detection coupling module can be linearly and uniformly distributed in the wavenumber space. Therefore, the signal processor of the detection coupling module can directly perform a Fourier transform on the detected interference spectrum signal, and then parse the reflection profile in the depth direction of the sample, without the need for additional re-collection of the interference spectrum signal, thereby effectively simplifying the processing of the data after the photoelectric conversion, and then improving the detection efficiency of PCB holes.

[0030] Furthermore, in a preferred embodiment of the present application, the bandwidth of the swept laser 1 is 100 nm, the sweep speed is 400 kHz, and the wavelength of the initial beam is 1060 nm. In actual use, the use of an ultra-wideband swept laser can significantly improve the axial resolution, thereby achieving higher accuracy in identifying PCB holes.

[0031] Furthermore, in a preferred embodiment of the present application, the light source module further includes a splitter coupler 2 , which receives the initial light beam of the swept laser 1 and splits it into a sample arm light beam and a reference arm light beam.

[0032] Further preferably, in a preferred embodiment of the present application, the intensity of the sample arm beam is not less than 80% and not more than 90%, the intensity of the reference arm beam is not less than 10% and not more than 20%, and the sum of the intensities of the two is 100%. Preferably, the intensity of the sample arm beam is 90%, and the intensity of the reference arm beam is 10%.

[0033] In actual use, since the reference arm beam is directly transmitted to the detection coupling module through the optical fiber, the reference arm beam will be directly transmitted before interference, and its intensity is relatively high. After the sample arm beam is reflected by the sample to form a return beam, it is actually backscattered light during the reflection process, and its intensity is relatively low. Therefore, choosing the sample arm beam intensity to be greater than the reference arm beam intensity can ensure accurate interference between the return beam and the reference arm beam.

[0034] Furthermore, in a preferred embodiment of the present application, the detection system also includes an optical fiber delay line 3, which receives the reference arm beam and is used to introduce a time delay to the transmission of the reference arm beam, thereby enabling the emission beam and the reference arm beam to enter the detection coupling module synchronously, ensuring the accuracy and stability of the interference signal, thereby achieving accurate measurement and imaging of the sample depth information.

[0035] Furthermore, in a preferred embodiment of the present application, the detection system further includes a polarization controller 4 , which receives the reference arm light beam transmitted from the optical fiber delay line 3 and changes the polarization state of the reference arm light beam.

[0036] Further preferably, in a preferred embodiment of the present application, the polarization controller 4 is a mechanical three-ring polarization controller 4, which utilizes the principle of induced birefringence of optical fiber under the action of external force, wherein the three rings are equivalent to three wave plates of λ / 4, λ / 2, and λ / 4 respectively. The light wave is converted into linearly polarized light through the λ / 4 wave plate, and then the polarization direction is adjusted by the λ / 2 wave plate. Finally, the polarization state of the linearly polarized light is changed into an arbitrary polarization state through the λ / 4 wave plate, thereby enabling the detection system to adjust the polarization state of the reference arm light beam according to the parameters of the PCB hole, thereby improving the adaptability of the detection system.

[0037] Furthermore, in a preferred embodiment of the present application, the fiber circulator 5 includes a first interface, a second interface, and a third interface. The first interface is connected to the light source module via an optical fiber, allowing the sample arm beam to enter the fiber circulator 5 through the first interface. The second interface corresponds to the first port, allowing the sample arm beam and the return beam to be transmitted between the two. The third interface is connected to the detection coupling module via an optical fiber, allowing the return beam to be transmitted to the detection coupling module via the optical fiber between the two.

[0038] Further preferably, in the preferred embodiment of the present application, the scanning module 8 includes a high-precision galvanometer and a piezoelectric ceramic displacement stage. The high-precision galvanometer is coaxial with the second port and is used to emit a sample arm beam or receive a return beam. The piezoelectric ceramic displacement stage is fixedly connected to the high-precision galvanometer and is used to control the movement position of the high-precision galvanometer.

[0039] In more detail, in a preferred embodiment of the present application, the scanning speed of the high-precision galvanometer is 500 Hz.

[0040] Furthermore, in a preferred embodiment of the present application, a fiber collimator 6 is provided between the fiber circulator 5 and the two-axis galvanometer 7. The fiber collimator 6 is used to adjust the parallelism of each light in the sample arm beam and, at the same time, can also receive the return beam.

[0041] Furthermore, in a preferred embodiment of the present application, the detection coupling module includes an interference coupler 10, a light detection module 11 and a signal processing module 12. The interference coupler 10 simultaneously receives the reference arm beam and the return beam, and interferes with the two to generate two interference signals. The light detection module 11 receives the interference signal and converts the interference signal into an electrical signal. The signal processing module 12 calculates the three-dimensional data of the hole based on the electrical signal. Further preferably, in a preferred embodiment of the present application, the interference coupler 10 includes two bundles of optical fibers for transmitting optical fiber signals, and the two bundles of optical fibers are respectively connected to the optical detection module 11. Preferably, the two bundles of optical fibers are respectively connected to the two input ports of the optical detector.

[0042] In more detail, in a preferred embodiment of the present application, the optical detection module 11 is a dual-balanced detector. Preferably, the bandwidth of the dual-balanced detector is 2.5 GHz, which is used to suppress common-mode noise. Specifically, the detector includes an ultra-low noise, high-speed transimpedance amplifier and two balanced photodiodes. In actual use, the two photodiodes are matched with each other, so that the optical detection module 11 can achieve a locally excellent common-mode rejection ratio, thereby better reducing noise. Preferably, the optical path design matches the mixed scenario of high and low reflectivity on the PCB surface. Further preferably, the reflectivity of the copper layer is greater than 90%, and the reflectivity of the dielectric layer is less than 5%.

[0043] Furthermore, in a preferred embodiment of the present application, the signal processing module 12 is based on real-time k-clock correction of a field-editable gate array and a GPU-accelerated deep learning denoising algorithm to ensure that the data throughput is greater than 8 GB / s at a sampling rate of 2 Gsample / s.

[0044] In actual use, the inspection system described in this application uses a 400kHz sweep rate (single A-scan time 2.5μs) and a 2Gsample / s acquisition card, combined with time-wavelength linearization technology, to compress single-hole inspection time to less than 10ms. This also significantly improves axial and lateral resolution.

[0045] Axial resolution: Based on a 100nm spectral bandwidth design, the theoretical axial resolution Δz=0.44*λ² / Δλ= 0.44*(1060nm)² / 100nm≈ 4.9μm (in air); λ0 is the central wavelength of the light source; △λ is the spectral width of the light source.

[0046] Lateral resolution: Using an objective lens NA = 0.4, a focused spot diameter d = 0.61λ0 / NA = 0.61×1060nm / 0.4≈1.6μm, combined with a scanning galvanometer closed-loop control accuracy of 0.1μrad, the actual lateral resolution is ≤5μm.

[0047] Furthermore, in a preferred embodiment of the present application, an ultra-high-speed frequency-sweeping laser PCB hole detection method is also disclosed, which includes the following steps: S1, the light emitted by the swept laser 1 passes through the optical splitter coupler 2 and is divided into 90% sample arm beam and 10% reference arm beam.

[0048] S2, the reference arm beam comes out through the optical fiber delay line 3, passes through the polarization controller 4 and is focused onto the interference coupler 10.

[0049] S3. The sample arm light beam passes through the fiber circulator 5 and is emitted as parallel light through the collimator. After passing through the two-axis galvanometer 7, the light beam can be driven by the scanning module to scan into a surface. After passing through the scanning module, it is focused on the sample. The sample arm light beam will have some backscattering when hitting the sample. The scattered return light beam comes out of the fiber circulator 5 and is received by the interference coupler 10.

[0050] S4. The reference beam and the return beam interfere with each other in the interference coupler 10. The interference signal is split into two beams and received by the balanced light detector, which converts the signal into an electrical signal and sends it to the signal processing unit.

[0051] S5. Adjust the processing parameters on the PC side to analyze and process the received data to obtain three-dimensional data.

[0052] The optical 3D micro-nano depth detection system of the present invention offers accurate detection, high speed, and good adaptability. By utilizing a swept laser 1 with a 400kHz sweep rate and a 2Gsample / s acquisition card, combined with time-wavelength linearization technology, it compresses the single-hole detection time to less than 10ms. Furthermore, the detection technology based on the coherent detection principle enables the detection system to detect deep microholes with diameters exceeding 30µm and aspect ratios reaching 20:1. Furthermore, the ultra-wideband swept light source significantly improves axial resolution, resulting in higher recognition accuracy for the detection results.

[0053] It will be easily understood by those skilled in the art that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Optical 3D micro-nano depth detection system, used for detecting holes on PCB boards, characterized by: include: A light source module, the light source module is used to generate and emit a sample arm beam and a reference arm beam with the same frequency, constant phase difference and the same polarization direction; A fiber optic circulator, wherein a first optical path is provided between the fiber optic circulator and the light source module, for receiving the sample arm light beam; A scanning module, comprising a scanning module and a two-axis galvanometer; the two-axis galvanometer comprises a first port and a second port through which light beams can be transmitted to each other, the first port being connected to the fiber optic circulator for entry of the sample arm light beam; a scanning module being provided on the second port, the scanning module being aligned with the PCB board and for emitting the sample arm light beam onto the PCB board; the sample arm light beam is irradiated onto the PCB board and forms a return light beam, which sequentially passes through the scanning module, the second port, and the first port into the fiber optic circulator; A detection coupling module is provided, wherein a second optical path is provided between the detection coupling module and the light source module, and a third optical path is provided between the detection coupling module and the fiber circulator, so that the detection coupling module simultaneously receives the reference arm beam and the return beam, and the reference arm beam and the return beam form interference in the detection coupling module to generate an interference signal, and the detection coupling module generates three-dimensional data of the hole according to the interference signal.

2. The optical 3D micro-nano depth detection system according to claim 1, wherein: The light source module includes a frequency-sweeping laser, which adapts to the transmission spectrum characteristics of the PCB board to provide an initial light beam, so that the K-clock signal of the initial light beam can generate a sampling trigger clock.

3. The optical 3D micro-nano depth detection system according to claim 2, wherein: The bandwidth of the frequency-sweeping laser is 100 nm, the frequency-sweeping speed is 400 kHz, and the wavelength of the initial light beam is 1060 nm.

4. The optical 3D micro-nano depth detection system according to claim 2 or 3, wherein: The light source module further includes a splitter coupler, which receives the initial light beam of the frequency-sweeping laser and splits it into a sample arm light beam and a reference arm light beam.

5. The optical 3D micro-nano depth detection system according to claim 4, wherein: The intensity of the sample arm light beam is not less than 80% and not more than 90%, the intensity of the reference arm light beam is not less than 10% and not more than 20%, and the sum of the intensities of the two is 100%.

6. The optical 3D micro-nano depth detection system according to any one of claims 1 to 3, wherein: The system further includes an optical fiber delay line, which receives the reference arm light beam and is used to introduce a time delay into the transmission of the reference arm light beam.

7. The optical 3D micro-nano depth detection system according to claim 6, wherein: The system further includes a polarization controller, which receives the reference arm light beam transmitted from the optical fiber delay line and changes the polarization state of the reference arm light beam.

8. The optical 3D micro-nano depth detection system according to any one of claims 1 to 3 and 7, wherein: The scanning module includes a high-precision galvanometer and a piezoelectric ceramic displacement stage. The high-precision galvanometer is coaxial with the second port and is used to emit a sample arm beam or receive the return beam. The piezoelectric ceramic displacement stage is fixedly connected to the high-precision galvanometer and is used to control the movement position of the high-precision galvanometer.

9. The optical 3D micro-nano depth detection system according to any one of claims 1 to 3 and 7, wherein: A fiber collimator is provided between the fiber circulator and the two-axis galvanometer, and the fiber collimator is used to adjust the parallelism of each light in the sample arm light beam.

10. The optical 3D micro-nano depth detection system according to any one of claims 1 to 3 and 7, wherein: The detection coupling module includes an interference coupler, a light detection module and a signal processing module. The interference coupler simultaneously receives the reference arm light beam and the return light beam, and interferes with the two to generate two interference signals. The light detection module receives the interference signal and converts the interference signal into an electrical signal. The signal processing module calculates the three-dimensional data of the hole based on the electrical signal.

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