Michelson interference high-precision optical micro-measurement device based on vortex filtering

Abstract

The utility model discloses a Michelson interference high-precision optical micro-measurement device based on vortex filtering, which relates to the technical field of precision measurement, and sequentially comprises a light field modulation module, an optical field detection module, a Michelson interference detection module, a Michelson interference detection module and a Michelson interference detection module along an optical path, the interference measurement module comprises a beam splitter, a reflector and a Dove prism arranged in a reference light path, the Dove prism enables the topological charges of the vortex beam to be reversed, and the Dove prism and the vortex beam in the measurement light path form composite mode interference light; the frequency domain filtering module is used for performing frequency domain filtering purification on the interference light; and the signal acquisition module is used for acquiring interference light spot images. According to the utility model, topological charge inversion is realized through the Dove prism, nanoscale displacement is linearly converted into macroscopic angle rotation of an interference pattern, frequency domain purification is carried out in combination with frequency domain filtering, and the signal-to-noise ratio and the resolution are remarkably improved; the device is compact in structure, multi-stage amplification and purification of displacement signals are achieved through a pure optical means, and micro-displacement measurement with nanoscale precision can be achieved.

Description

Technical Field

[0001] This utility model belongs to the field of precision measurement technology, specifically relating to a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry. Background Technology

[0002] In fields such as precision machining and microelectromechanical systems (MEMS) testing, the demand for non-contact, high-precision measurement of nanometer-level micro-displacements and micro-angles is increasingly urgent as product feature dimensions continue to shrink and precision requirements rise. Micro-displacement measurement technology, as the foundation of precision measurement, directly affects machining accuracy, assembly quality, and device performance. Optical measurement methods, due to their advantages of non-contact operation, high sensitivity, and rapid response, have become the mainstream technology in precision measurement, with interferometry receiving widespread attention for its wavelength-level measurement resolution.

[0003] The traditional Michelson interferometer is one of the most classic tools in optical measurement. Its basic principle is to use the shift of interference fringes of coherent light to invert changes in optical path difference, thereby achieving displacement measurement. With technological advancements, researchers have attempted to introduce vortex light into the field of interferometry. Vortex light, due to its orbital angular momentum and helical phase structure, exhibits extremely high sensitivity to phase changes, providing a new physical dimension for improving measurement accuracy. Existing technologies have explored combining vortex light with various interference structures, which to some extent expands the application possibilities of vortex light in precision measurement.

[0004] However, existing vortex interferometry techniques still have significant shortcomings. Most research remains at the application level of a single vortex mode. Although traditional Michelson interferometers have the advantages of symmetrical optical paths and strong anti-interference capabilities, current technologies lack a device design that systematically integrates them with vortex mode conversion functions. In addition, existing devices are mostly built with discrete components, making optical path adjustment complex, and repeatability and practicality need to be improved. Utility Model Content

[0005] To address the aforementioned problems in the existing technology, this invention provides a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry, comprising the following components arranged sequentially along the optical path:

[0007] An optical field modulation module is used to generate a vortex beam carrying a preset topological charge. The optical field modulation module includes a laser, a collimation system and a spatial light modulator arranged sequentially along the optical path. The spatial light modulator is connected to a control computer that loads a phase hologram.

[0008] An interferometric measurement module is used to transmit the vortex beam to a measurement optical path and a reference optical path. In the reference optical path, a Dowell prism reverses the topological charge of the vortex beam, and the topologically inverted vortex beam forms a compound-mode interference beam with the vortex beam in the measurement optical path. The interferometric measurement module includes a first beam splitter, a second beam splitter, a first reflector, a second reflector, and the Dowell prism, arranged sequentially along the optical path. The vortex beam is transmitted to the measurement optical path and the reference optical path after passing through the first beam splitter and the second beam splitter sequentially. The first reflector is disposed in the measurement optical path, and the Dowell prism and the second reflector are sequentially disposed in the reference optical path.

[0009] A frequency domain filtering module is used to perform frequency domain filtering on the composite mode interference light; the frequency domain filtering module includes a first lens, a vortex filter and a second lens arranged sequentially along the optical path, the first lens and the second lens constitute a 4f Fourier transform system, and the vortex filter is arranged on the Fourier surface of the 4f Fourier transform system.

[0010] The signal acquisition module is used to acquire the interference spot image after frequency domain filtering.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0012] This invention relates to a Michelson interferometric high-precision optical micro-measurement device based on vortex filtering. Through modular integration, it combines vortex light generation, compound-mode interference based on a Dove prism, and frequency-domain filtering and purification to form a complete high-precision optical micro-measurement solution. Its core lies in using a Dove prism in the reference optical path to invert the topological charge of the vortex beam, thereby forming a highly displacement-sensitive compound-mode interference with the original vortex light in the measurement optical path. Subsequently, a frequency-domain filtering module purifies the interference light, effectively suppressing noise and providing a high-quality light source for subsequent high-precision signal acquisition. This compact design and clear optical path achieve multi-stage amplification and purification of the displacement signal through purely optical means, laying a solid foundation for achieving nanometer-level measurement accuracy.

[0013] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0014] Figure 1 This is a structural block diagram of a Michelson interferometer high-precision optical micro-measuring device based on vortex filtering, provided in an embodiment of this utility model.

[0015] Icons: 100-Optical field modulation module; 200-Interferometric measurement module; 300-Frequency domain filtering module; 400-Signal acquisition module; 110-Laser; 120-Collimation system; 130-Spatial light modulator; 140-Control computer; 210-First beam splitter; 220-Second beam splitter; 230-First reflecting mirror; 240-Second reflecting mirror; 250-Dowell prism; 260-Piezoelectric ceramic micro-displacement platform; 270-Precision rotary stage; 310-Third beam splitter; 320-First lens; 330-Vortex filter; 340-Second lens; 500-Computer. Detailed Implementation

[0016] To further illustrate the technical means and effects adopted by this utility model to achieve its intended purpose, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, describes a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry proposed according to this utility model.

[0017] The foregoing and other technical contents, features, and effects of this utility model will be clearly presented in the following detailed description of the specific embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by this utility model to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the technical solution of this utility model.

[0018] This utility model embodiment provides a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry. Please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a structural block diagram of a Michelson interferometric high-precision optical micro-measuring device based on vortex filtering, provided in an embodiment of this utility model. Figure 1 As shown, the Michelson interferometric high-precision optical micro-measurement device based on vortex filtering in this embodiment includes an optical field modulation module 100, an interferometric measurement module 200, a frequency domain filtering module 300, and a signal acquisition module 400 arranged sequentially along the optical path.

[0019] The optical field modulation module 100 is used to generate a vortex beam carrying a preset topological charge as a probe optical field. In this embodiment, the optical field modulation module 100 includes a laser 110, a collimation system 120, and a spatial light modulator 130 arranged sequentially along the optical path. The laser 110 may be a helium-neon laser, used to provide a laser beam with high coherence and stable output. The collimation system 120 is composed of a lens group, used to shape the diverging laser beam emitted by the laser 110 into a parallel beam of appropriate diameter. The spatial light modulator 130 may be a reflective liquid crystal spatial light modulator, which is connected to a control computer 140. The control computer 140 has a preset topological charge number pre-stored, such as the topological charge number. The phase hologram required for the vortex beam. When the parallel beam shines on the spatial light modulator 130, it is modulated by the loaded phase hologram, thereby emitting a vortex beam carrying a predetermined orbital angular momentum.

[0020] The interferometric measurement module 200 is used to receive the vortex beam from the optical field modulation module 100 and transmit the vortex beam to the measurement optical path and the reference optical path. In the reference optical path, the topological charge of the vortex beam is reversed by passing through the Dowell prism. The reversed vortex beam merges with the vortex beam in the measurement optical path to form a composite mode interference beam.

[0021] Specifically, the interferometric measurement module 200 includes a first beam splitter 210, a second beam splitter 220, a first reflector 230, a second reflector 240, and a Dowell prism 250 arranged sequentially along the optical path. The vortex beam is transmitted to the measurement optical path and the reference optical path after passing through the first beam splitter 210 and the second beam splitter 220 in sequence; the first reflector 230 is disposed in the measurement optical path, and the Dowell prism 250 and the second reflector 240 are disposed sequentially in the reference optical path.

[0022] Specifically, the vortex beam emitted from the optical field modulation module 100 first enters the first beam splitter 210 and is split into two beams: one transmitted and one reflected. The transmitted beam, serving as the probe beam, is split into two beams by the second beam splitter 220, which then enter the reference optical path and the measurement optical path, respectively. In the measurement optical path, the beam illuminates the first reflecting mirror 230 and is reflected back to the second beam splitter 220. In the reference optical path, the beam passes sequentially through the Dowell prism 250 and the second reflecting mirror 240 before returning along its original path.

[0023] Based on the optical properties of vortex light, when a beam of vortex light passes through a Dowell prism 250, its topological charge will be inverted, i.e., it will change from a vortex charge to a vortex charge that is not induced by the optical property of vortex light. Become The beam with inverted topological charge and the beam with unchanged topological charge in the measurement path converge at the second beam splitter 220, forming a pair of composite mode vortex beams with opposite topological charges. These vortex beams interfere with each other, producing composite mode interference light with a specific "petal" pattern. This interference pattern is extremely sensitive to the optical path difference between the measurement and reference optical paths.

[0024] To precisely control and utilize this sensitivity, the interferometric measurement module 200 also includes a piezoelectric ceramic micro-displacement platform 260 and a precision rotary stage 270. A first reflecting mirror 230 is mounted on the piezoelectric ceramic micro-displacement platform 260. The piezoelectric ceramic micro-displacement platform 260 can be a closed-loop controlled piezoelectric ceramic nanopositioning stage, which can drive the first reflecting mirror 230 to generate precise, repeatable nanoscale displacements, such as 10 nm steps, for simulating the displacement to be measured or for system calibration. A Dowell prism 250 is mounted on the precision rotary stage 270. The precision rotary stage 270 can be an electrically driven rotary displacement stage, through which the azimuth angle of the Dowell prism 250 can be finely adjusted, thereby optimizing the interference conditions of the two composite vortex beams and obtaining an interference pattern with optimal contrast. This design is a crucial guarantee for the high-precision, repeatable measurement of this device.

[0025] For example, both the first reflector 230 and the second reflector 240 can be right-angle prisms to reduce the number of components in the optical path and simplify assembly.

[0026] It should be noted that, due to the use of the Dowell prism 250 to generate compound-mode vortex interference, when the measurement optical path experiences a slight change in optical path difference due to the displacement of the first reflecting mirror 230, the "petal"-shaped pattern produced by the interference will rotate accordingly. This design utilizes the optical leverage effect to linearly amplify the nanoscale linear displacement, which is difficult to measure directly, into a macroscopic angle rotation of the light spot that is easy to observe and calculate, thereby significantly improving the measurement sensitivity.

[0027] The frequency domain filtering module 300 is used to perform frequency domain filtering on the composite mode interference light output by the interferometry module 200 to remove noise and purify the signal. In this embodiment, the frequency domain filtering module 300 includes a third beam splitter 310, a first lens 320, a vortex filter 330, and a second lens 340 arranged sequentially along the optical path. The first lens 320 and the second lens 340 constitute a standard 4f Fourier transform system, and the vortex filter 330 is disposed on the Fourier surface of the 4f Fourier transform system. One of the beams of the vortex beam emitted from the optical field modulation module 100, after being split by the first beam splitter 210 of the interferometry module 200, is transmitted to the vortex filter 330 after passing through the third beam splitter 310.

[0028] The composite mode interference light emitted from the interferometry module 200 is first reflected (or transmitted) by the third beam splitter 310, and then enters the filtered optical path composed of the first lens 320, the vortex filter 330, and the second lens 340. After passing through the first lens 320, the interference light field forms a spatial spectrum distribution on its back focal plane, i.e., the Fourier surface of the 4f Fourier transform system. The vortex filter 330 is precisely placed on this Fourier surface, and its core is a carefully designed amplitude or phase mask. The function of the vortex filter 330 is to perform mode filtering of the light field in the frequency domain, allowing only the target vortex mode, such as those with a topological charge number of 1 / 2π / 2. The matched spectral components pass through, effectively filtering out stray light, environmental noise, and other irrelevant spatial frequency components, significantly improving the signal-to-noise ratio and mode purity of the output signal. The filtered spectrum is then subjected to an inverse Fourier transform by the second lens 340, restoring an interference spot image with higher resolution and a cleaner background in the spatial domain.

[0029] The signal acquisition module 400 is used to acquire the frequency-domain filtered interference spot image. In this embodiment, the signal acquisition module 400 includes a photodetector, which is used to acquire the interference spot image and convert it into an electrical signal output. Exemplarily, the photodetector can be a CMOS (Complementary Metal Oxide Semiconductor) or CCD (Charge-Coupled Device) camera, which can clearly acquire the filtered and purified "petal"-shaped interference spot image and convert it into a digital electrical signal.

[0030] In an optional embodiment, the Michelson interferometric high-precision optical micro-measuring device based on vortex filtering in this embodiment further includes a computer 500 connected to the signal acquisition module 400. The computer 500, acting as a data processing unit, receives image data from the photodetector and runs built-in dedicated software. This software integrates advanced algorithms such as Fourier-Melin transform, Kalman filtering, and RANSAC (Random Sample Consensus), enabling it to accurately calculate the rotation angle of the interferogram from the acquired image. Combined with a pre-calibrated displacement-angle model, it ultimately calculates and outputs the corresponding nanometer-level displacement or micro-angle value.

[0031] Furthermore, the workflow and principle of the Michelson interferometric high-precision optical micro-measuring device based on vortex filtering in this embodiment are fully explained.

[0032] During the system preparation and optical path adjustment phase, the laser 110 is first turned on, and the spatial light modulator 130 is driven by the control computer 140 to generate the required topological charge (e.g., ...). The system first generates a vortex beam. Then, the optical components are carefully adjusted to be coaxial, and the angle of the Dowell prism 250 is finely adjusted by a precision rotary stage 270 until a clear, high-contrast compound vortex light interference "petal" pattern is observed on the preview image of the photodetector, thus completing the system initialization.

[0033] Next, the displacement measurement process begins. If it is a calibration or known displacement measurement, the piezoelectric ceramic micro-displacement platform 260 drives the first reflecting mirror 230 to generate precise nanometer-level displacement, for example, in 10 nm increments. If it is an unknown sample measurement, the sample to be measured is placed on the piezoelectric ceramic micro-displacement platform 260, and the displacement of the sample drives the first reflecting mirror 230 to move. This displacement causes a slight change in the optical path difference between the measurement optical path and the reference optical path. This change directly causes the "petal" pattern generated by the interference of the two composite vortex beams to rotate.

[0034] During the signal purification and acquisition stage, the rotating interference light field enters the filtering process. First, it undergoes a Fourier transform via the first lens 320. On the Fourier surface, a vortex filter 330 filters out noise components of non-target modes. Then, it undergoes an inverse Fourier transform via the second lens 340, ultimately outputting a clean interference spot image with significantly improved signal-to-noise ratio and resolution. This image is acquired by a high-resolution photodetector.

[0035] Finally, data processing and calculation are performed. The image acquired by the photodetector is transmitted to the computer 500. The software algorithm in the computer 500 automatically extracts the rotation angle of the light spot image and performs smoothing processing such as Kalman filtering on the angle sequence. Finally, combined with the pre-calibrated "angle-displacement" conversion model of the system, the nanometer-level displacement of the first reflecting mirror 230 is calculated and output with high precision.

[0036] This invention relates to a Michelson interferometric high-precision optical micro-measuring device based on vortex filtering. It combines three technologies—vortex light detection, Dowell prism optical lever amplification, and vortex filtering purification—to achieve high-precision, non-contact measurement of nanoscale micro-displacements. By introducing a Dowell prism to generate compound-mode vortex light interferometry, the traditional interferometer's measurement of fringe movement is transformed into the measurement of the rotation angle of the interference petals. Utilizing the optical lever effect and angle subdivision, a measurement resolution far exceeding half-wavelength is achieved. By integrating a piezoelectric ceramic micro-displacement platform and a precision rotating stage, precise control and repeatable measurement of the optical path are realized. A 4f Fourier transform system combined with a vortex filter purifies and enhances the signal resolution in the spatial frequency domain, fundamentally improving the system's signal-to-noise ratio and measurement accuracy.

[0037] This invention relates to a high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry. It modularly integrates key functions such as vortex light generation, mode conversion, displacement excitation, and frequency domain filtering within the Michelson interferometer framework. It features a compact structure, strong anti-interference capability, high visualization of the measurement process, and flexible configuration. It can effectively improve the accuracy, efficiency, and reliability of micro-displacement measurement and is suitable for online measurement needs in fields such as precision manufacturing and microelectromechanical systems testing.

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply 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 construed as a limitation of the invention.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0040] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications or substitutions should be considered within the protection scope of the present invention.

Claims

1. A high-precision optical micro-measuring device based on vortex filtering and Michelson interferometry, characterized in that, Including those arranged sequentially along the optical path: An optical field modulation module is used to generate a vortex beam carrying a preset topological charge. The optical field modulation module includes a laser, a collimation system and a spatial light modulator arranged sequentially along the optical path. The spatial light modulator is connected to a control computer that loads a phase hologram. An interferometric measurement module is used to transmit the vortex beam to a measurement optical path and a reference optical path. In the reference optical path, a Dowell prism reverses the topological charge of the vortex beam, and the topologically inverted vortex beam forms a compound-mode interference beam with the vortex beam in the measurement optical path. The interferometric measurement module includes a first beam splitter, a second beam splitter, a first reflector, a second reflector, and the Dowell prism, arranged sequentially along the optical path. The vortex beam is transmitted to the measurement optical path and the reference optical path after passing through the first beam splitter and the second beam splitter sequentially. The first reflector is disposed in the measurement optical path, and the Dowell prism and the second reflector are sequentially disposed in the reference optical path. A frequency domain filtering module is used to perform frequency domain filtering on the composite mode interference light; the frequency domain filtering module includes a first lens, a vortex filter and a second lens arranged sequentially along the optical path, the first lens and the second lens constitute a 4f Fourier transform system, and the vortex filter is arranged on the Fourier surface of the 4f Fourier transform system. The signal acquisition module is used to acquire the interference spot image after frequency domain filtering.

2. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, The interferometric measurement module also includes a piezoelectric ceramic micro-displacement platform, on which the first reflector is mounted, and the first reflector is displaced at the nanometer level by means of the piezoelectric ceramic micro-displacement platform.

3. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, The interferometric measurement module also includes a precision rotating stage, on which the Dowell prism is mounted, and the orientation angle of the Dowell prism is adjusted by means of the precision rotating stage.

4. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, Both the first and second reflectors are right-angle prisms.

5. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, The frequency domain filtering module further includes a third beam splitter. One of the beams of light after the vortex beam is split by the first beam splitter of the interferometric measurement module is transmitted to the vortex filter after passing through the third beam splitter.

6. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, The signal acquisition module includes a photodetector, which is used to acquire the interference spot image and convert it into an electrical signal output.

7. The Michelson interferometric high-precision optical micro-measuring device based on vortex filtering according to claim 1, characterized in that, It also includes a computer connected to the signal acquisition module, which is used to perform data processing and calculation on the interference spot image.

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