Optical coherence tomography-based self-lubricating bearing coating thickness detection system and method

Abstract

The present application relates to a kind of based on optical coherence tomography self-lubricating bearing coating thickness detection system and method, the system includes: tungsten halogen lamp light source module, for emitting light beam;First convex lens, for the emitted light of tungsten halogen lamp light source module is collimated as parallel light beam;Michelson interferometer module, for the light beam is split into two light beams of equal intensity, as reference light, probe light respectively converge in reference mirror, bearing coating surface to be measured, after reflection, interference occurs, and interference light beam is formed;And two-dimensional spectrometer module, including mirror, reflective grating, column lens and area array CCD camera, interference light beam is propagated to reflective grating by mirror, and after wavelength is spectrally dispersed in space, interference spectrum line is converged by column lens, and two-dimensional interference spectrum stripe is obtained by area array CCD camera acquisition, and then bearing coating thickness information is obtained.The system and method are beneficial to the non-contact nondestructive testing of self-lubricating bearing coating thickness, and measurement speed is fast, and detection precision is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection, and particularly relates to a self-lubricating bearing coating thickness detection system and method based on optical coherence tomography. BACKGROUND

[0002] The self-lubricating bearing is simple in structure, compact in structure, large in bearing capacity, and is widely used in mechanical equipment in high-precision fields such as aerospace, high-speed transportation and military equipment. The wear, cracks and bubbles of the bearing coating seriously affect the bonding and lubricating performance of the coating, and the coating thickness directly affects the service life of the bearing pin shaft assembly. At present, the detection of the bearing coating is mainly the scanning electron microscope and energy spectrometer detection after the end face is polished and ground, which is a destructive detection of the coating and the bearing part, and there is a difference from the actual working condition of the self-lubricating coating, so it is difficult to realize high-precision measurement of the overall coating thickness. SUMMARY

[0003] The application aims to provide a self-lubricating bearing coating thickness detection system and method based on optical coherence tomography, which is beneficial to non-contact and non-destructive detection of the self-lubricating bearing coating thickness, has fast measurement speed and high detection precision.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows: a self-lubricating bearing coating thickness detection system based on optical coherence tomography, comprising:

[0005] A tungsten halogen lamp light source module is used for emitting a light beam.

[0006] A first convex lens is used for collimating the point light beam emitted by the tungsten halogen lamp light source module into a parallel light beam.

[0007] A Michelson interferometer module is used for splitting the light beam into two light beams with equal intensity as reference light and detection light, which are converged on a reference mirror and a bearing coating surface to be detected respectively, and after reflection, the two light beams are superimposed to generate interference, forming an interference light beam.

[0008] A two-dimensional spectrometer module comprises a mirror, a reflection grating, a cylindrical lens and a face array CCD camera. The interference light beam is transmitted to the reflection grating through the mirror, and after being spectrally dispersed in space according to the wavelength, the interference spectrum line is converged by the cylindrical lens, and the two-dimensional interference spectrum stripe is obtained by the face array CCD camera. The bearing coating thickness information is obtained through image processing and calculation.

[0009] Further, the Michelson interferometer module comprises a beam splitter, a second convex lens, a plane mirror and a third convex lens, the plane mirror serving as a reference mirror, the beam splitter splits the incident light beam into two light beams of equal intensity, one of which is converged on the reference mirror as reference light via the second convex lens, and the other of which is converged on the surface of the bearing coating sample on the three-dimensional moving platform as probe light via the third convex lens, the two light beams interfere after being reflected to the beam splitter, and are emitted to the mirror of the two-dimensional spectrometer module.

[0010] Further, a computer is further included, and an image processing and calculation software module is installed on the computer, which is used to calculate the bearing coating thickness information according to the obtained two-dimensional interference spectrum fringes.

[0011] The application further provides a self-lubricating bearing coating thickness detection method based on the above system, comprising the following steps:

[0012] In step S1, a point light beam is emitted by the tungsten halogen lamp light source module, collimated into a parallel light beam via the convex lens, and then split into two light beams of equal intensity by the beam splitter of the Michelson interferometer module, one of which is converged on the reference mirror of the Michelson interferometer module as reference light, and the other of which is converged on the surface of the bearing coating sample to be measured as probe light, the two light beams interfere after being reflected to the beam splitter, the interference light beams are emitted to the mirror of the two-dimensional spectrometer module, and then propagate to the reflective grating after being reflected; the reflective grating spatially splits light according to wavelengths, and then converges into interference spectrum lines by the cylindrical lens of the two-dimensional spectrometer module, and two-dimensional interference spectrum fringes are obtained by the surface array CCD camera;

[0013] In step S2, the two-dimensional spectrometer module transmits the collected interference spectrum fringe image to the computer, processes the fringe signal, and performs fast Fourier transform on a series of collected images to extract the intensity variation frequency of each row of pixel points.

[0014] In step S3, the intensity variation frequency of each row of pixel points is multiplied by the system distance resolution determined by the wavelength calibration and the self-built spectrometer to obtain the tomographic structure of the sample to be measured.

[0015] Further, in step S2, the signal collected by the spectrometer after the light source passes through the reference light path is:

[0016] I R(A) =S R(k) e 2ikr (1)

[0017] In the formula, S R(k) is the spectral power distribution function of the reference light, e 2ikr is the phase, 2r is the optical path length of the reference ratio, and k is the wave number and k=2π / λ.

[0018] The sample reflected light is:

[0019]

[0020] In the formula, S S(k,z) is the spectral power distribution function of the reflected light corresponding to different depths of the sample, n is the reflectivity of the sample; r+nz is the optical path corresponding to the sample at depth z;

[0021] When the reference light and the reflected light interfere, the system receives and converts into an interference spectrum signal:

[0022]

[0023] The formula (3) is the real interference spectrum signal, and the actually collected signal is the optical interference signal of the self-lubricating bearing coating area:

[0024]

[0025] Further, in the step S3, the calculation method of the layer analysis structure diagram of the sample to be measured is:

[0026]

[0027] In the formula, represents convolution operation; multiplying the signal by the system distance resolution determined by the self-built spectrometer is the information of the bearing coating in depth, that is, the layer analysis structure diagram of the sample to be measured is obtained.

[0028] Compared with the prior art, the present application has the following beneficial effects: the present application obtains the two-dimensional interference fringe image of the bearing coating, and effectively obtains the thickness information of the self-lubricating bearing coating through signal processing, without damaging the coating and the bearing, without polishing and grinding, and realizing high-precision nondestructive detection of the thickness of the self-lubricating bearing coating, overcoming the defect that the traditional system and method need destructive detection. Therefore, the present application has strong practicability and broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a two-dimensional structure schematic diagram of the system of the embodiment of the present application.

[0030] Figure 2 is a three-dimensional structure schematic diagram of the system of the embodiment of the present application.

[0031] Figure 3 is a self-lubricating bearing coating sample in the embodiment of the present application.

[0032] Figure 4 is a coating layer analysis structure diagram in the embodiment of the present application.

[0033] Figure 5Table 1 is a comparison table of the detection results of the partial self-lubricating bearing coating samples in the embodiments of the present application and the actual coating thickness.

[0034] In the figure: 1, tungsten halogen lamp light source module; 2, first convex lens; 3, first plane mirror; 4, second convex lens; 5, beam splitter; 6, third convex lens; 7, bearing coating sample to be measured; 8, three-dimensional precision moving platform; 9, second plane mirror; 10, reflective grating; 11, cylindrical lens; 12, area array CCD camera. DETAILED DESCRIPTION

[0035] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains.

[0037] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the present specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0038] As shown in Figure 1 , 2 The present embodiment provides a self-lubricating bearing coating thickness detection system based on optical coherence tomography, which comprises a tungsten halogen lamp light source module 1, a first convex lens 2, a Michelson interferometer module and a two-dimensional spectrometer module.

[0039] The tungsten halogen lamp light source module 1 is used to emit a light beam.

[0040] The first convex lens 2 is used to collimate the point beam emitted by the tungsten halogen lamp light source module 1 into a parallel light beam.

[0041] The Michelson interferometer module is used for splitting the light beam into two light beams with equal intensity as reference light and probe light, which are converged on the reference mirror and the bearing coating surface to be measured respectively, and the interference occurs after the reflection and superposition to form an interference light beam. In the embodiment, the Michelson interferometer module comprises a beam splitter 5, a second convex lens 4, a first plane mirror 3 as a reference mirror, and a third convex lens 6. The beam splitter 5 splits the incident light beam into two light beams with equal intensity, one of which is used as reference light and converged on the reference mirror 3 through the second convex lens 4, and the other of which is used as probe light and converged on the bearing coating sample surface on the three-dimensional precision moving platform 8 through the third convex lens 6. The two light beams interfere after being reflected to the beam splitter 5, and are emitted to the second plane mirror 9 of the two-dimensional spectrometer module.

[0042] The two-dimensional spectrometer module comprises the second plane mirror 9, a reflective grating 10, a cylindrical lens 11, and a plane array CCD camera 12. The interference light beam propagates to the reflective grating 10 through the second plane mirror 9, is spectrally dispersed according to wavelength, is converged into an interference spectrum line by the cylindrical lens 11, and is collected by the plane array CCD camera 12 to obtain a two-dimensional interference spectrum fringe. The bearing coating thickness information is obtained through image processing and calculation.

[0043] In the embodiment, the system further comprises a computer on which an image processing and calculation software module is installed, which is used for calculating the bearing coating thickness information according to the obtained two-dimensional interference spectrum fringe.

[0044] The embodiment also provides a self-lubricating bearing coating thickness detection method based on the above system, which comprises the following steps:

[0045] In step S1, the tungsten halogen lamp light source module emits a point light beam, which is collimated into a parallel light beam by a convex lens, and then split into two light beams with equal intensity by the beam splitter of the Michelson interferometer module. One of the two light beams is used as reference light and converged on the reference mirror of the Michelson interferometer module, and the other of the two light beams is used as probe light and converged on the bearing coating sample surface. The sample structure is shown in Figure 3 After being reflected to the beam splitter, the two light beams interfere, the interference light beam is emitted to the mirror of the two-dimensional spectrometer module, propagates to the reflective grating after being reflected, and is spectrally dispersed according to wavelength by the reflective grating, converged into an interference spectrum line by the cylindrical lens of the two-dimensional spectrometer module, and collected by the plane array CCD camera to obtain a two-dimensional interference spectrum fringe.

[0046] In step S2, the two-dimensional spectrometer module transmits the collected interference spectrum fringe image to the computer, processes the fringe signal, and performs fast Fourier transform on a series of collected images to extract the intensity change frequency of each row of pixel points.

[0047] In step S3, the intensity change frequency of each row of pixel points is multiplied by the system distance resolution determined by the wavelength calibration and the self-built spectrometer to obtainFigure 4 The chromatogram of the sample to be measured is shown.

[0048] In the step S2, the signal collected by the spectrometer after the reference light path is:

[0049] I R(A) = S R(k) e 2ikr (1)

[0050] In the formula, S R(k) is the spectral power distribution function of the reference light, e 2ikr is the phase, 2r is the optical path length of the reference ratio, k is the wave number and k = 2π / λ.

[0051] The sample reflected light is:

[0052]

[0053] In the formula, S S(k,z) is the spectral power distribution function of the reflected light corresponding to different depths of the sample, n is the reflectivity of the sample; r+nz is the optical path corresponding to the depth z of the sample.

[0054] When the reference light and the reflected light interfere, the system receives and converts into an interference spectrum signal:

[0055]

[0056] The formula (3) obtains the real interference spectrum signal, and the actually collected signal is the optical interference signal of the self-lubricating bearing coating area:

[0057]

[0058] In the step S3, the calculation method of the chromatogram of the sample to be measured is:

[0059]

[0060] In the formula, represents convolution operation; multiplying the signal by the system distance resolution determined by the self-built spectrometer is the information of the bearing coating in depth, that is, the chromatogram of the sample to be measured is obtained.

[0061] In this embodiment, the system and method are used to detect the thickness of a plurality of self-lubricating bearing coating samples, and the comparison between the detection results and the actual coating thickness is shown in Table 1 in the Figure 5 From the experimental comparison results, it can be seen that the system and method have strong feasibility and accuracy.

[0062] The above merely describes preferred embodiments of the present application, but is not intended to limit the present application to other forms, and any person skilled in the art can make changes or modifications to the above disclosed technical contents into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution content of the present application and according to the technical essence of the present application still belongs to the protection scope of the technical solution of the present application.

Claims

1. An optical coherence tomography-based method for detecting the thickness of a self-lubricating bearing coating, characterized in that, The application relates to a bearing coating thickness measuring device, which comprises the following modules: a tungsten halogen lamp light source module for emitting a light beam; a first convex lens for collimating the point light beam emitted by the tungsten halogen lamp light source module into a parallel light beam; a Michelson interferometer module for splitting the light beam into two light beams with equal intensity as reference light and probe light which are respectively converged on a reference mirror and a bearing coating surface to be measured, and the interference occurs after the reflected light beams are superimposed to form an interference light beam; and a two-dimensional spectrometer module comprising a mirror, a reflective grating, a cylindrical lens and a plane array CCD camera, the interference light beam is transmitted to the reflective grating through the mirror, and the light beam is spectrally dispersed in space according to wavelengths and then converged into an interference spectrum line by the cylindrical lens, the two-dimensional interference spectrum stripe is obtained by the plane array CCD camera, and the bearing coating thickness information is obtained through image processing and calculation; the Michelson interferometer module comprises a beam splitter, a second convex lens, a plane mirror and a third convex lens, the plane mirror serves as the reference mirror, the beam splitter splits the incident light beam into two light beams with equal intensity, one of the two light beams serves as the reference light and is converged on the reference mirror through the second convex lens, and the other light beam serves as the probe light and is converged on the bearing coating sample surface on a three-dimensional moving platform, the two light beams are reflected to the beam splitter to interfere, and the interference light beam is emitted to the mirror of the two-dimensional spectrometer module; a computer is further arranged, and an image processing and calculation software module is installed on the computer and used for calculating the bearing coating thickness information according to the obtained two-dimensional interference spectrum stripe; the application further discloses a bearing coating thickness measuring method, which comprises the following steps: step S1: the tungsten halogen lamp light source module emits a point light beam, the point light beam is collimated into a parallel light beam through the convex lens, and then the parallel light beam is split into two light beams with equal intensity by the beam splitter of the Michelson interferometer module, one of the two light beams serves as the reference light and is converged on the reference mirror of the Michelson interferometer module, and the other light beam serves as the probe light and is converged on the bearing coating sample surface, the two light beams are reflected to the beam splitter to interfere, the interference light beam is emitted to the mirror of the two-dimensional spectrometer module, and then the interference light beam is transmitted to the reflective grating after being reflected; the reflective grating spectrally disperses the light beam in space according to wavelengths, and then the light beam is converged into an interference spectrum line by the cylindrical lens of the two-dimensional spectrometer module, and the two-dimensional interference spectrum stripe is obtained by the plane array CCD camera; step S2: the two-dimensional spectrometer module transmits the collected interference spectrum stripe image to the computer, processes the stripe signal, and performs fast Fourier transform on a series of collected images to extract the intensity variation frequency of each row of pixel points; step S3: the intensity variation frequency of each row of pixel points is multiplied by the system distance resolution determined by the wavelength calibration and the self-built spectrometer, and then the sample layer structure diagram to be measured is obtained; in the step S2, the signal collected by the spectrometer after the light source passes through the reference light path is: (1) wherein is the spectral power distribution function of the reference light, is the phase, is the optical path length of the reference ratio, is the wave number and ; the sample reflected light is: (2) wherein is the spectral power distribution function of the reflected light for different depths of the sample, is the reflectivity of the sample; is the optical path of the sample at depth corresponding. when the reference light and the reflected light interfere, the system receives and converts the interference into an interference spectrum signal: (3) the interference spectrum signal obtained by the formula (3) is the real interference spectrum signal, and the actually collected signal is the optical interference signal of the self-lubricating bearing coating area: (4) in the step S3, the calculation method of the sample layer structure diagram to be measured is: (5) In the formula, represents convolution operation; multiplying the signal by the system distance resolution determined by the self-built spectrometer is the information of the bearing coating in depth detected, that is, the tomographic structure of the sample to be measured is obtained.

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