CN105333816A - Super lateral resolution surface three-dimensional online interference measuring system based on spectral dispersion full field - Google Patents

Abstract

The invention discloses a three-dimensional on-line interferometric measurement system for a surface with super lateral resolution based on spectral dispersion full field, belonging to the field of optical measurement. The system consists of broadband light source, isolator, optical fiber and optical fiber connector, spherical and cylindrical lens, beam splitter, rectangular prism, diaphragm, grating, reflector, area detector, photodetector, Fabry-Perot Filter, piezoelectric ceramics, signal processing, feedback control, data acquisition card, computer, translation stage and translation stage drive, result output, etc. The grating disperses the broadband spectrum into a light sheet with continuous distribution of wavelengths in the transverse direction, and the expanded beam is vertically incident on the surface to be measured for full-field measurement; two wavelengths are used to measure steps with a height difference greater than half the wavelength and grooves with a large aspect ratio Surface; Fabry-Perot filter is used to achieve super lateral resolution measurement; feedback control compensates environmental interference to make the system suitable for online measurement, and the measurement results are accurately traceable to the wavelength reference, and are not affected by the spectral drift of the light source.

Description

A 3D online surface interferometry system with super lateral resolution based on spectral dispersion full field

technical field

The invention relates to the field of optical measurement, in particular to a three-dimensional on-line interferometry system for surfaces with super lateral resolution based on spectral dispersion full field.

Background technique

The existing literature close to this technology has the following two:

[1] D.P.Hand, T.A.Carolan, J.S.Barton, and J.D.C.Jones. "Profile measurement of optically rough surfaces by fiber-optic interferometry", Opt. Lett., Vol.18, No.16, 1993, P.1361-1363. (Optics Letters (Optics Letters) , Volume 18, Issue 16, P.1361-1363)

The technical principle of literature [1] is shown in Figure 1.

The light emitted by the semiconductor laser passes through the Faraday isolator and the fiber 3dB coupler, and then reaches the measuring head. The measuring head is a Fizeau interferometer. Part of the light is reflected by the end face of the fiber as the reference light, and the other part of the light is focused by the self-focusing lens and projected On the measured surface, it is reflected by the measured surface and returns to the system and interferes with the reference light. The interference signal is detected by the detector, and the phase of the interference signal is determined by the longitudinal height of the measured point on the measured surface; changing the laser’s Drive the current to change the luminous frequency of the laser, measure the same point with four different frequencies of light, and get four interference signals. Due to the different frequencies of the incident light waves, the phases of the four interference signals are different. Adjust the drive current to make adjacent The phase difference π/2 of the two interference signals can be demodulated to obtain the optical path difference D of the point through the following formula, that is, to complete the measurement of a single point:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\mathrm{<span\; class="notranslate">\; \&nu;</span>}}{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span>$

I _n (n=1,2,3,4) is the intensity of the nth interference signal, c is the speed of light, and ν is the frequency of the incident light.

The stepper motor then drives the measuring head to scan the surface to be measured horizontally, that is, the measurement of the surface to be measured is completed.

[2]DejiaoLin,XiangqianJiang,FangXie,WeiZhang,LinZhangandIanBennion.“Highstabilitymultiplexedfibreinterferometeranditsapplicationonabsolutedisplacementmeasurementandon-linesurfacemetrology”，OpticsExpress,Vol.12,Issue23,2004,P.5729-5734.(OpticsExpress(光学特快),2004年,第12卷,第Issue 23, P.5729-5734)

The technical schematic diagram of literature [2] is shown in Figure 2.

The system consists of two Michelson interferometers with nearly coincident optical paths. One Michelson interferometer is composed of a fiber grating on the measuring arm and a reference mirror as a mirror to complete the stable work; the other Michelson interferometer is composed of a measuring mirror and a reference mirror as a mirror to complete the measurement work . Because the reference arms of the two interferometers share a mirror, the optical paths of the reference arms of the two interferometers are completely coincident, and because the measuring arms of the two interferometers are almost coincident, so when one interferometer is stable, the other interferometer is stable. stabilized.

The light with a wavelength of _λ0 emitted by the semiconductor laser is divided into two paths after passing through two 3dB couplers, one path is reflected by the fiber grating, and the other path is reflected by the reference mirror. The two reflected lights meet again after passing through the 3dB coupler and interfere with each other. After the interference signal passes through the circulator, it is reflected by another fiber grating, passes through the circulator again, and then is detected by the detector. The signal detected by the detector passes through the servo circuit. After processing, the piezoelectric ceramic tube is driven to adjust the length of the reference arm of the fiber optic interferometer, so that the two interference arms of the stable interferometer are always in an orthogonal state (phase difference is π/2), thereby achieving the purpose of stabilizing the interferometer.

The wavelength λ _m variable light emitted by the tunable laser is divided into two paths after passing through two optical fiber 3dB couplers. One path passes through the fiber optic self-collimation lens, and then is reflected by the measuring mirror and returns to the interferometer again. The other path passes through the optical fiber After the self-collimating lens is reflected by the reference mirror and returns to the interferometer again, the two paths of light meet after passing through the 3dB coupler to form an interference signal, which is detected by the detector after passing through the circulator and fiber grating, and then passes through the phase Analysis means measuring the displacement of the measuring mirror.

The problem and the deficiency that above-mentioned two prior art exist are:

1. The light spot scans the surface to be measured for three-dimensional surface measurement. The light spot needs to be scanned in two dimensions to complete the three-dimensional surface measurement. The scanning mechanism is complicated and the measurement speed is slow.

2. The horizontal resolution of the measurement depends on the diameter of the spot, which is limited by the diffraction limit. Therefore, the lateral resolution depends on the diffraction limit, and it is difficult to obtain measurement results with high lateral resolution.

3. It is not possible to measure surfaces with steps with a height difference greater than half a wavelength and grooves with a large aspect ratio.

Contents of the invention

The present invention utilizes a light sheet with continuous distribution of wavelengths in the transverse direction (perpendicular to the light wave propagation direction) formed by the diffraction grating dispersion broadband spectrum, and expands the light sheet into a parallel light beam that is vertically incident on the surface to be measured, and conducts full-field inspection on the surface to be measured. Measurement, complete three-dimensional measurement of the surface in one positioning, no need to scan, fast measurement speed; use two different wavelengths to measure the same measured point on the measured surface, and tune the difference between the two wavelengths to obtain different sizes The wavelength of the synthetic wave enables the system to perform three-dimensional rapid measurement of steps with a height difference of millimeter order and the discontinuous surface of grooves with an aspect ratio greater than 50; using a tunable Fabry-Perot filter to achieve super lateral resolution in the direction of light length ; Use the feedback control system to compensate the influence of environmental interference on the measurement system to improve the anti-interference ability of the measurement system, making it suitable for on-line measurement; the diffraction grating dispersion broadband spectrum forms a light sheet with continuous distribution of wavelengths in the lateral direction and fixed wavelength positions, so that The measurement results can be accurately traced to the wavelength reference, and the drift of the light source spectrum has no effect on the measurement results.

The present invention is achieved through the following technical solutions.

A three-dimensional on-line surface interferometry system with super lateral resolution based on spectral dispersion full field, consisting of broadband light source X1, isolator B1, optical fiber F, optical fiber connector C, spherical convex lenses L1, L2, L3, cylindrical convex lenses L4, L5 . Detector PD1, area detector PD2, tunable Fabro-Perot filter X2, piezoelectric ceramic PZT, data acquisition card B2, signal processing circuit B3, feedback control circuit B4, computer B5, result output B6, translation stage drive B7 composition.

The light emitted by the broadband light source X1 passes through the isolator B1 and the optical fiber F, and is output by the fiber optic connector C. The parallel beam formed by the collimation of the spherical convex lens L1 is focused on the back focus of the spherical convex lens L2 after passing through the spherical convex lens L2. The circular aperture stop D1 located at the back focus of L2, and then the parallel light beam formed by the collimation of the spherical convex lens L3 is incident on the right-angle prism R1, turned by the right-angle prism R1, and reaches the beam splitter S1, which is divided into two beams of transmission and reflection by the beam splitter S1 The transmitted light reaches the beam splitter S2, and then is divided into two beams of light by the beam splitter S2, the transmitted light and the reflected light. The reflected light beam is reflected out of the system, and the transmitted light beam is incident on the cylindrical convex lens L4 along the main optical axis of the cylindrical convex lens L4, and is received by the cylindrical convex lens L4. Focusing on the rear focal point of the cylindrical convex lens L4, the rear focal point of the cylindrical convex lens L4 is on the diffraction surface of the diffraction grating G, so the light beam is focused on the diffraction grating G, and then dispersed by the diffraction grating G to form a wavelength in the horizontal direction (vertical A fan-shaped light sheet continuously distributed in the direction of light wave propagation. The fan-shaped light sheet is collimated by the cylindrical convex lens L5 into a parallel light sheet with continuous wavelength distribution in the transverse direction. The parallel light sheet is expanded into a parallel beam by two confocal cylindrical convex lenses L6 and L7, and the parallel beam reaches the beam splitter S3 , is divided into two beams of transmitted and reflected light, wherein the transmitted parallel light is incident on the plane mirror M, reflected by the plane mirror M, returns to the beam splitter S3 again, and then reflected and transmitted by the beam splitter S3 into two parallel beams.

The parallel light beams from the cylindrical convex lens L7 and reflected by the beam splitter S3 are projected on the measured surface, and different measured points on the measured surface reflect back light of different wavelengths. The reflected light reaches the beam splitter S3 again, and is divided by the beam splitter S3 into two parallel beams of transmitted and reflected light. The transmitted parallel light beam meets and interferes with the parallel light reflected by the plane mirror M and reaches the beam splitter S3 and reflected by the beam splitter S3. The light of each wavelength forms its own interference signal, and the interfering parallel beam reaches the beam splitter S4. And is divided into two beams of parallel light beams by beam splitter S4, transmission and reflection. The transmitted parallel light beam is vertically incident on a parallel plate of the Fabry-Perot filter X2, and the light of the wavelength satisfying the coherent and constructive conditions of the Fabry-Perot filter X2 can be transmitted, and the adjacent wavelength interval is the free spectral region of the Fabry-Perot filter The comb-shaped wavelength light passes through the Fabry-Perot filter X2 to form a comb-shaped parallel beam with discontinuous cross-sectional light energy, which is detected by the corresponding pixel of the area array detector PD2. The interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on a set of equally spaced measured lines on the measured surface and the reflected light of the plane mirror M, and the interference of each wavelength in the comb-shaped wavelengths The signal carries longitudinal information corresponding to the measured point. The interference signal detected by the area detector PD2 is input to the computer B5 after passing through the data acquisition card B2.

In order to measure other points, the translation stage T2 drives a parallel plate of the Fabry-Perot filter X2 to move, thereby adjusting the cavity length of the Fabry-Perot filter X2, so that the other group satisfies the coherence and phase length of the Fabry-Perot filter The comb wavelength passes through and is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 is input to the computer B5 after passing through the data acquisition card B2. The interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on the measured line with another group of equal intervals on the measured surface and the reflected light of the plane mirror M. Therefore, each of the comb-shaped wavelengths The interference signal of each wavelength carries the longitudinal information corresponding to the measured point. By repeating this, the interference signal formed by the meeting between the reflected light of each measured point on the measured surface and the reflected light of the plane mirror M is detected by the area detector PD2. The computer B5 demodulates the interference signal to realize the full-field measurement of the surface where the vertical height difference between two adjacent measured points is not greater than half a wavelength, and the measurement result is output by the result output B6.

Due to the function of the light-blocking screen P, the beam reflected from the beam splitter S1 cannot reach the interferometer, so it does not affect the measurement. At this time, only the beam transmitted from the beam splitter S1 reaches the interferometer and the measured surface, and participates in the completion of the measurement. Work.

For the measurement of discontinuous surfaces with steps and grooves where the vertical height difference between two adjacent measured points is greater than half the wavelength, first, according to the above steps, the area array detector PD2 detects the reflection of each measured point on the measured surface The interference signal formed by the light is input to the computer B5 after the interference signal passes through the data acquisition card B2. Then, the light blocking screen P is moved to the position of the beam transmitted from the beam splitter S1 (as shown in the figure, the position of the dotted line between the beam splitters S1 and S2), and the light blocking screen P blocks the beam transmitted from the beam splitter S1, so that not involved in the measurement. The light beam reflected by the beam splitter S1 is diverted by the rectangular prisms R2 and R3, then reaches the beam splitter S2, and is divided into two beams of reflected and transmitted beams by the beam splitter S2, the transmitted beam exits the measurement system, and the reflected beam deviates from the main light of the cylindrical convex lens L4 axis but parallel to the main optical axis of the cylindrical convex lens L4 incident on the cylindrical convex lens L4, is focused on the back focus of the cylindrical convex lens L4. Because the back focus of the cylindrical convex lens L4 is on the diffraction surface of the diffraction grating G, the light beam is focused on the diffraction surface of the diffraction grating G, and then dispersed by the diffraction grating G to form a fan-shaped light sheet with continuous distribution of wavelengths in the transverse direction. The fan-shaped light sheet is collimated by the cylindrical convex lens L5 into a parallel light sheet with continuous distribution of wavelengths in the transverse direction. Since the incident angle of this beam of light on the diffraction grating G is different from the incident angle of the beam of light passing through the main optical axis of the cylindrical convex lens L4 (beams transmitted from the beam splitter S1 and the beam splitter S2) on the diffraction grating G, the two The two wavelengths formed by the beam light diffracted by the diffraction grating G are in the horizontally continuously distributed fan-shaped light sheets, and the spatial positions of each wavelength are different in the two fan-shaped light sheets; the wavelengths formed by the collimation of the lens L5 are in the spatial distribution For parallel wave plates, the positions of each wavelength are laterally misaligned between the two parallel light plates. The parallel light sheet is expanded into a parallel beam by two confocal cylindrical convex lenses L6 and L7. The parallel beam reaches the beam splitter S3 and is divided into two beams of transmitted and reflected light. The transmitted parallel light is incident on the plane mirror M. It is reflected by the plane mirror M, returns to the beam splitter S3 again, and is reflected and transmitted by the beam splitter S3 into two parallel beams. The parallel light beam reflected by the beam splitter S3 is projected on the measured surface, and different measured points on the measured surface reflect back light of different wavelengths. The reflected light reaches the beam splitter S3 again, and is divided by the beam splitter S3 into two parallel beams of transmitted and reflected light. Among them, the transmitted beam meets and interferes with the parallel light reflected by the plane reflector M, reaches the beam splitter S3 and is reflected by S3, each wavelength of light forms its own interference signal, and the interfering parallel beam reaches the beam splitter S4, and is separated by the beam splitter S4 is divided into two parallel beams of transmission and reflection. The transmitted light beam is vertically incident on a parallel plate of the Fabry-Perot filter X2, the light of the wavelength satisfying the coherent and constructive conditions of the Fabry-Perot filter X2 can be transmitted, and the interval between adjacent wavelengths is the comb in the free spectral region of the Fabry-Perot filter The light with the wavelength of the wavelength passes through the Fabry-Perot filter X2 to form a comb-shaped parallel beam with discontinuous light energy in the cross section, which is detected by the corresponding pixel of the area array detector PD2. The interference signal detected by the area detector PD2 is input to the computer B5 after passing through the data acquisition card B2. The interference signal of this set of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on a group of equally spaced discrete measured lines on the measured surface and the reflected light of the plane mirror M. The interference signal carries longitudinal information corresponding to the measured point.

In order to measure other points, the longitudinal translation stage T3 drives a parallel plate of the Fabry-Perot filter X2 to move, thereby adjusting the cavity length of the Fabry-Perot filter X2, so that the other group meets the coherence and phase-contrast conditions of the Fabry-Perot filter The comb wavelength passes through and is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 is input to the computer B5 after passing through the data acquisition card B2. The interference signal of this group of comb-shaped wavelengths is formed by meeting the reflected light of each point on another group of discrete measured lines with equal intervals on the measured surface and the reflected light of the plane mirror M. Therefore, each of the comb-shaped wavelengths The interference signal of each wavelength carries the longitudinal information corresponding to the measured point. Repeating this, the interference signal formed by the meeting of the reflected light of each measured point on the measured surface and the reflected light of the plane mirror M is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 After passing through the data acquisition card B2, input it into the computer B5.

The computer B5 demodulates the input interference signal to realize the full-field measurement on the surface of steps and deep grooves with a height difference greater than half a wavelength, and the measurement results are output by the result output B6. Because the lateral positions of each wavelength in the two fan-shaped light sheets are different, it is possible to use two different wavelengths to respectively measure the same measured point on the measured surface. The interference signals of the two wavelengths are demodulated to realize the three-dimensional measurement of the surface with steps and deep grooves with a height difference greater than half the wavelength.

The interfering parallel light beam reflected by the beam splitter S4 reaches the slit diaphragm D2, and each point of this light is an interference signal formed by a different wavelength, and the interference signal passing through the slit diaphragm D2 reaches the photodetector PD1, and is detected by the photodetector PD1 detection. After the interference signal detected by PD1 is processed by the signal processing circuit B3, it is processed by the feedback control circuit B4, and the output signal of the feedback control circuit B4 is added to the piezoelectric ceramic PZT located in the reference arm of the interferometer to drive the PZT to adjust the reference of the interferometer. The optical path of the arm keeps the two interference arms of the interferometer in an orthogonal state, thereby eliminating the influence of environmental interference on the interferometer, thereby achieving the purpose of stabilizing the measurement system and making the measurement system suitable for on-line measurement.

Further, as a preferred solution, use the fan-shaped light sheet formed by the diffraction grating G dispersion broadband spectrum to continuously distribute the wavelength in the lateral direction, expand the fan-shaped light sheet into a parallel beam that is vertically incident on the measured surface, and perform Full-field three-dimensional measurement, only one positioning is required to complete the three-dimensional measurement of the surface to be measured, and the measurement speed is fast.

Further, as a preferred solution, two wavelengths of light are used to measure the same measured point on the surface to be measured, and by demodulating the interference signals of the two wavelengths, the measurement system can measure the height difference greater than half the wavelength. Three-dimensional measurement of discontinuous surfaces of steps and trenches with large aspect ratios.

Further, as a preferred solution, the diffraction grating G dispersion broadband spectrum is used to form parallel beams with continuous distribution of wavelengths in space and constant spatial positions of various wavelengths, so that the measurement results can be accurately traced to the wavelength reference, and the spectral drift of the light source has no effect on the measurement results. influences. This not only improves the ability of the measurement system to resist environmental interference such as temperature drift, but also lays a solid foundation for obtaining high measurement accuracy.

Further, as a preferred solution, the Fabry-Perot filter X2 is used to convert the parallel beams whose wavelengths are continuously distributed in the lateral direction into comb-shaped parallel beams whose energy is discontinuous in the lateral direction, so as to improve the lateral resolution in the direction of wavelength arrangement.

Further, as a preferred solution, the output signal of the feedback control circuit B4 is applied to the piezoelectric ceramic PZT located in the reference arm of the interferometer, and the PZT is driven to adjust the optical path of the reference arm of the interferometer, so that the two The interference arm is kept in an orthogonal state, thereby eliminating the influence of environmental interference on the interferometer, improving the anti-interference ability of the measurement system, achieving the purpose of stabilizing the measurement system, and making the measurement system suitable for online measurement.

The beneficial effects of the present invention mainly contain:

1. Use the diffraction grating G dispersion broadband spectrum to form a fan-shaped light sheet with continuous distribution of wavelengths in the transverse direction (perpendicular to the light wave transmission direction), expand the fan-shaped light sheet into a parallel beam, and the parallel beam is vertically incident on the surface to be measured. The surface under test is measured in full-field 3D. The three-dimensional measurement of the surface can be completed in one positioning, and the measurement speed is fast.

2. Use two wavelengths of light to measure the same measured point on the surface to be measured, and by demodulating the interference signals of the two wavelengths, the measurement system can measure steps with a height difference greater than half a wavelength and a large aspect ratio Three-dimensional measurement of the discontinuous surface of the trench.

3. Use the diffraction grating G dispersion broadband spectrum to form parallel light beams with continuous distribution of wavelengths in the lateral direction and constant spatial positions of various wavelengths, so that the measurement results can be accurately traced to the wavelength reference, and the spectral drift of the light source has no effect on the measurement results.

4. Use the Fabry-Perot filter X2 to convert the parallel beams whose wavelengths are continuously distributed in the transverse direction into comb-shaped parallel beams whose energy is discontinuous in the transverse direction, so as to improve the transverse resolution in the direction of wavelength arrangement.

5. Use the output signal of the feedback control circuit B4 to add to the piezoelectric ceramic PZT located in the reference arm of the interferometer, drive the PZT to adjust the optical path of the reference arm of the interferometer, and keep the two interference arms of the interferometer at the orthogonal State, so as to eliminate the influence of environmental interference on the interferometer, improve the anti-interference ability of the measurement system, achieve the purpose of stabilizing the measurement system, and make the measurement system suitable for online measurement.

Description of drawings

Fig. 1 is the schematic diagram of prior art literature [1];

Fig. 2 is the schematic diagram of prior art document [2];

Fig. 3 is a schematic diagram of the present invention.

detailed description

The present invention will be further described below in combination with FIG. 3 and specific embodiments.

As shown in Figure 3, the system consists of broadband light source X1, isolator B1, optical fiber F, optical fiber connector C, spherical convex lenses L1, L2, L3, cylindrical convex lenses L4, L5, L6, L7, beam splitters S1, S2, S3 , S4, rectangular prisms R1, R2, R3, diaphragms D1, D2, diffraction grating G, light blocking screen P, plane mirror M, translation stage T1, T2, photodetector PD1, area array detector PD2, adjustable Fabro-Perot filter X2, piezoelectric ceramic PZT, data acquisition card B2, signal processing circuit B3, feedback control circuit B4, computer B5, result output B6, and translation stage driver B7.

The light emitted by the broadband light source X1 passes through the isolator B1 and the optical fiber F, and is output by the optical fiber connector C. After being collimated by the spherical convex lens L1, the parallel beam formed by the spherical convex lens L2 is focused on the back focus of the spherical convex lens L2, and passes through the The circular aperture stop D1 at the rear focus of the spherical convex lens L2, and then the parallel beam formed by the collimation of the spherical convex lens L3 is incident on the right-angle prism R1 for turning, and reaches the beam splitter S1, which is divided into two beams of transmitted and reflected light by the beam splitter S1. After reaching the beam splitter S2, the beam splitter S2 is then divided into two beams of transmitted and reflected light, and the reflected beam is reflected out of the system. The transmitted light beam is incident on the cylindrical convex lens L4 along the main optical axis of the cylindrical convex lens L4, and is focused on the back focus of the cylindrical convex lens L4. The back focus of the cylindrical convex lens L4 is on the diffraction surface of the diffraction grating G, so the light beam is It is focused on the diffraction grating G, and then dispersed by the diffraction grating G to form a fan-shaped light sheet in which the wavelengths are continuously distributed in space. The fan-shaped light sheet is collimated by the cylindrical convex lens L5 into a parallel light sheet with continuous wavelength distribution in space. The parallel light sheet is expanded into a parallel beam by two confocal cylindrical convex lenses L6 and L7, and the parallel beam reaches the beam splitter S3 , is divided into two beams of transmitted and reflected light, wherein the transmitted parallel light is incident on the plane mirror M, reflected by the plane mirror M, returns to the beam splitter S3 again, and then reflected and transmitted by the beam splitter S3 into two parallel beams. The parallel light beam reflected by the beam splitter S3 is projected on the measured surface, and different measured points on the measured surface reflect back light of different wavelengths. The reflected light reaches the beam splitter S3 again, and is divided by the beam splitter S3 into two parallel beams of transmitted and reflected light. Among them, the transmitted beam meets and interferes with the parallel light reflected by the plane reflector M, reaches the beam splitter S3 and is reflected by the beam splitter S3, and the light of each wavelength forms its own interference signal, and the interfering parallel beam reaches the beam splitter S4, and is detected The beam splitter S4 splits the transmission and reflection into two parallel beams. The transmitted light beam is vertically incident on a parallel plate of the Fabry-Perot filter X2, and the light of the wavelength satisfying the coherent and constructive conditions of the Fabry-Perot filter X2 can be transmitted, and the interval between adjacent wavelengths is the comb in the free spectral region of the Fabry-Perot filter. The light of the Fabry-Perot filter X2 passes through the Fabry-Perot filter X2 to form a comb-shaped parallel beam with discontinuous light energy in the cross-section, which is detected by the corresponding pixel of the area array detector PD2, and the interference signal detected by the area array detector PD2 is collected through data collection. Enter computer B5 after card B2. The interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on a set of equally spaced measured lines on the measured surface and the reflected light of the plane mirror M, and the interference of each wavelength in the comb-shaped wavelengths The signal carries longitudinal information corresponding to the measured point.

In order to measure other points, the longitudinal translation stage T3 drives a parallel plate of the Fabry-Perot filter X2 to move, thereby adjusting the cavity length of the Fabry-Perot filter X2, so that the other group meets the coherence and phase-contrast conditions of the Fabry-Perot filter The comb-shaped wavelength passes through and is detected by the area array detector PD2. The interference signal of this group of comb-shaped wavelengths is formed by the reflected light of each point on the measured line at another group of equal intervals on the measured surface and the plane reflector M. The reflected light meets to form, therefore, the interference signal of each wavelength in the comb wavelength carries the longitudinal information corresponding to the measured point. Repeating this, the interference signal formed by the meeting of the reflected light of each measured point on the measured surface and the reflected light of the plane mirror M is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 After passing through the data acquisition card B2, it is input into the computer B5.

In order to demodulate the longitudinal information of the measured point from the interference signal, the optical path difference of the interferometer needs to be linearly modulated during measurement. For this reason, during the process of detecting interference signals by the area array detector PD2, the longitudinal translation stage T1 drives the measured object to move linearly in the longitudinal direction (perpendicular to the measured surface), and linearly modulates the optical path difference of the interferometer. Corresponding to the area detector PD2N×M pixels, the number of measured points on the measured surface is N×M, and the measured points are arranged in N rows and M columns, corresponding to the interference signal of the jth measured point in the i-th row Can be expressed as:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; v</span>}\mathrm{<span\; class="notranslate">\; t</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula: A _{(i, j)0} is the DC amount of the interference signal, A _{(i, j)} is the visibility of the interference signal, △ _{(i, j)} is the measured value of the jth point of the interferometer in the i row The optical path difference, n is the refractive index of air, v is the moving speed of the longitudinal moving station T1, t is the time for the longitudinal moving station T1 to modulate the optical path difference, and λ _j is the reflected wavelength of the jth measured point.

The interference signal corresponding to the j+1th measured point in the i-th row can be expressed as:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; v</span>}\mathrm{<span\; class="notranslate">\; t</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: A _{(i, j+1)0} is the DC amount of the interference signal, A _{(i, j+1)} is the visibility of the interference signal, △ _{(i, j+1)} is the i-th line of the Michelson interferometer The optical path difference of the j+1th measured point, n is the air refractive index, v is the moving speed of the vertical moving station T1, t is the time for the vertical moving station T1 to modulate the optical path difference, λ _j+1 is the j+th 1 The wavelength reflected by the measured point.

When a parallel light beam whose wavelength is continuously distributed in the transverse direction (the direction of wave propagation) is incident vertically on a parallel plate of the tunable Fabry-Perot filter X2, only light with a wavelength satisfying the coherent and constructive conditions of (3) will pass through ,

2nd = kλ(3)

Where: d is the cavity length of the Fabry-Perot filter X2, n is the refractive index of air, k is a positive integer, and λ is the wavelength of light. When the wavelength _λj satisfies the coherent and constructive conditions of the Fabry-Perot filter X2, the interference signal in (1) will pass through the Fabry-Perot filter and be detected by the pixel corresponding to the spatial position on the area detector PD2, The detected signals are:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the formula: T is the transmittance of the two opposite sides of the Fabry-Perot filter X2 two parallel plates, R is the reflectance of the two opposite sides of the Fabry-Perot filter X2 two parallel plates, I _{(i, j)} is incident to the Fabry-Perot filter X2 Light intensity of Perot filter X2.

In formula (4), since T and R are constants, as the optical path difference of the interferometer is linearly modulated, I _{(i, j)} changes in a cosine law, and the signal detected by the area array detector PD2 also changes in a cosine law . Similarly, the signal corresponding to the j+1th measured point detected by the area detector PD2 also changes in a cosine law. Compare the phase difference of the two cosine signals, and then measure the vertical height difference between the jth measured point in the i row and the j+1th measured point on the measured surface according to the phase difference. By repeating this process, the longitudinal height difference of each pair of adjacent measured points is demodulated, that is, the three-dimensional measurement of the surface is realized in which the vertical height difference of two adjacent measured points is not greater than half a wavelength.

For the measurement of discontinuous surfaces with steps and grooves where the vertical height difference between two adjacent measured points is greater than half the wavelength, first, according to the above steps, the area array detector PD2 detects the interference of each measured point on the measured surface signal, and input the interference signal into the computer B5 after passing through the data acquisition card B2. Then, the light blocking screen P is moved to the position of the beam transmitted from the beam splitter S1 (as shown in the figure, the position of the dotted line between the beam splitters S1 and S2), and the light blocking screen P blocks the beam transmitted from the beam splitter S1, so that It does not participate in the measurement. The beam reflected by the beam splitter S1 is diverted by the right-angle prisms R2 and R3, and then reaches the beam splitter S2. The main optical axis of the convex lens L4 is incident on the cylindrical convex lens L4 in a direction parallel to the main optical axis of the cylindrical convex lens L4, and is focused on the back focus of the cylindrical convex lens L4. Because the back focus of the cylindrical convex lens L4 is on the diffraction surface of the diffraction grating G, the light beam is focused on the diffraction surface of the diffraction grating G, and then dispersed by the diffraction grating G to form a fan-shaped light sheet with continuous distribution of wavelengths in the transverse direction. The fan-shaped light sheet is collimated by the cylindrical convex lens L5 into a parallel light sheet with continuous distribution of wavelengths in the transverse direction. Since the incident angle of this beam of light on the diffraction grating G is different from that of the beam of light passing through the main optical axis of the cylindrical convex lens L4 (beams transmitted from S1 and S2) on the diffraction grating G, the two beams of light are diffracted The two wavelengths formed after the diffraction of the grating G are in the horizontally continuously distributed fan-shaped light sheets, and the spatial positions of each wavelength in the two fan-shaped light sheets are different; the wavelengths formed by collimating through the cylindrical convex lens L5 are parallel Wave plate, each wavelength has a lateral misalignment in the spatial position of the two parallel light plates. The parallel light sheet is expanded into a parallel beam by two confocal cylindrical convex lenses L6 and L7. The parallel beam reaches the beam splitter S3 and is divided into two beams of transmitted and reflected light. The transmitted parallel light is incident on the plane mirror M. It is reflected by the plane mirror M, returns to the beam splitter S3 again, and is reflected and transmitted by the beam splitter S3 into two parallel beams. The parallel light beam reflected by the beam splitter S3 is projected on the measured surface, and different measured points on the measured surface reflect back light of different wavelengths. The reflected light reaches the beam splitter S3 again, and is divided by the beam splitter S3 into two parallel beams of transmitted and reflected light. Among them, the transmitted beam meets and interferes with the parallel light reflected by the plane reflector M, reaches the beam splitter S3 and is reflected by the beam splitter S3, and the light of each wavelength forms its own interference signal, and the interfering parallel beam reaches the beam splitter S4, and is detected The beam splitter S4 splits the transmission and reflection into two parallel beams. The transmitted light beam is vertically incident on a parallel plate of the Fabry-Perot filter X2, and the light of the wavelength satisfying the coherent and constructive conditions of the Fabry-Perot filter X2 can be transmitted, and the interval between adjacent wavelengths is the comb in the free spectral region of the Fabry-Perot filter. The light with a wavelength of 100 mm passes through the Fabry-Perot filter X2 to form a comb-shaped parallel beam of cross-sectional light energy, which is detected by the corresponding pixel of the area array detector PD2, and the interference signal detected by the area array detector PD2 passes through the data acquisition card B2 Enter computer B5. The interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of a group of equally spaced discrete points on the measured surface on the measured surface and the reflected light of the plane mirror M, and the interference of each wavelength in the comb-shaped wavelengths The signal carries longitudinal information corresponding to the measured point.

In order to measure other points, the longitudinal translation stage T3 drives a parallel plate of the Fabry-Perot filter X2 to move, thereby adjusting the cavity length of the Fabry-Perot filter X2, so that the other group meets the coherence and phase-contrast conditions of the Fabry-Perot filter The comb wavelength passes through and is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 is input to the computer B5 after passing through the data acquisition card B2. The interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on the measured surface and the reflected light of the plane mirror M. Therefore, each of the comb-shaped wavelengths The interference signal of each wavelength carries the longitudinal information corresponding to the measured point. So repeated, the interference signal formed by the meeting of the reflected light of each measured point on the measured surface and the reflected light of the plane mirror M is detected by the area array detector PD2, and the interference signal detected by the area array detector PD2 passes through the data After collecting the card B2, input it into the computer B5.

Because the spatial position of each wavelength in the two fan-shaped light sheets is different, it is possible to use two different wavelengths to measure the same measured point on the measured surface respectively.

Correspondingly, the area array detector has N×M pixels to detect the interference signal, and there are N×M measured points on the measured surface. When the light beam transmitted by the beam splitter S1 participates in the measurement, the phase of the interference signal detected by the jth pixel in the i-th row of the area array detector PD2 is:

When the light beam reflected by the beam splitter S1 participates in the measurement, the phase of the interference signal detected by the same pixel in the same row of the area detector PD2 (the j-th pixel in the i-th row) is:

In formula (5) and formula (6): and is the phase of the interference signal, and is the fractional part of the phase of the interference signal (i.e. the initial phase), m _1(i,j) and m _2(i,j) are positive integers, △ _(i,j) is the jth measured value of the interferometer in row i The optical path difference of the point, λ _1j and λ _2j are the wavelengths incident to the jth point to be measured.

Similarly, when the light beam transmitted by the beam splitter S1 participates in the measurement, the phase of the interference signal detected by the j+1th pixel in the i-th row of the area array detector PD2 is:

When the light beam reflected by the beam splitter S1 participates in the measurement, the phase of the interference signal detected by the j+1th pixel in the i-th row of the area array detector PD2 is:

In formula (7) and formula (8): and is the phase of the interference signal, and is the fractional part of the phase of the interference signal (that is, the initial phase), m _{1(i, j+1)} and m _{2(i, j+1)} are positive integers, △ _{(i, j+1)} is the interferometer in row i The optical path difference of the j+1th measured point of , λ _1(j+1) and λ _2(j+1) are the wavelengths incident to the j+1th measured point.

The vertical height difference between the j+1th measured point and the jth measured point in the i-th row on the measured surface is:

In the formula: n is the refractive index of air, i=1,2,...,N, j=1,2,...,M-1.

The longitudinal height difference of each pair of adjacent measured points is demodulated, that is, the measurement of discontinuous surfaces of steps and grooves whose longitudinal height difference between two adjacent measured points is greater than half a wavelength is realized.

The interfering parallel light beam reflected by the beam splitter S4 reaches the slit diaphragm D2, and each point of this light is an interference signal formed by a different wavelength, and the interference signal passing through the slit diaphragm D2 reaches the photodetector PD1, and is detected by the photodetector PD1 detection. After the interference signal detected by PD1 is processed by the signal processing circuit B3, it is processed by the feedback control circuit B4, and the output signal of the feedback control circuit B4 is added to the piezoelectric ceramic PZT located in the reference arm of the interferometer to drive the PZT to adjust the reference of the interferometer. The optical path of the arm keeps the two interference arms of the interferometer in an orthogonal state, thereby eliminating the influence of environmental interference on the interferometer, thereby achieving the purpose of stabilizing the measurement system and making the measurement system suitable for on-line measurement.

In order to illustrate the realization of the present invention, the above-mentioned specific examples have been described, but other changes and modifications of the present invention are obvious to those skilled in the art, and any modification/change within the essence and basic principle scope of the present invention does not have disclosure Or imitation conversion all belong to the scope of protection of the claims of the present invention.

Claims (6)

1. A super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field, characterized by a broadband light source (X1), an isolator (B1), an optical fiber (F), an optical fiber connector (C), a spherical surface Convex lens (L1, L2, L3), cylindrical convex lens (L4, L5, L6, L7), beam splitter (S1, S2, S3, S4), rectangular prism (R1, R2, R3), diaphragm (D1, D2 ), light barrier (P), diffraction grating (G), plane mirror (M), translation stage (T1, T2), photodetector (PD1), area detector (PD2), tunable Fabro-Perot Filter (X2), piezoelectric ceramics (PZT), data acquisition card (B2), signal processing circuit (B3), feedback control circuit (B4), computer (B5), result output (B6), translation stage driver (B7 ) composition; the light emitted by the broadband light source (X1) passes through the isolator (B1) and the optical fiber (F), and is output by the optical fiber connector (C), and the parallel beam formed by the collimation of the spherical convex lens (L1) passes through the spherical convex lens (L2 ), it is focused at the rear focal point of the spherical convex lens (L2), passes through the circular aperture stop (D1) at the rear focal point of (L2), and then collimated by the spherical convex lens (L3) to form a parallel beam incident on the rectangular prism ( On R1), it is turned by the right-angle prism (R1), reaches the beam splitter (S1), and is divided into two beams of light by the beam splitter (S1), the transmitted light and the reflected light. Divided into two beams of light, transmitted and reflected, the reflected beam is reflected out of the system, and the transmitted beam is incident on the cylindrical convex lens (L4) along the main optical axis of the cylindrical convex lens (L4), and is focused at the back focus of the cylindrical convex lens (L4) , the back focus of the cylindrical convex lens (L4) is on the diffraction surface of the diffraction grating (G), so the light beam is focused on the diffraction grating (G), and then dispersed by the diffraction grating (G), forming a wavelength in the transverse direction (perpendicular to The fan-shaped light sheet is continuously distributed in the direction of light wave propagation), and the fan-shaped light sheet is collimated by a cylindrical convex lens (L5) into a parallel light sheet with a continuous distribution of wavelengths in the lateral direction. This parallel light sheet passes through two confocal cylindrical convex lenses (L6) and (L7) expand the beam into a parallel beam, which reaches the beam splitter (S3) and is divided into two beams of transmission and reflection, wherein the transmitted parallel light is incident on the plane mirror (M) and is captured by the plane mirror (M) Reflected, back to the beam splitter (S3) again, and then reflected and transmitted by the beam splitter (S3) into two parallel beams; the parallel beams from the cylindrical convex lens (L7) and reflected by the beam splitter (S3) are projected on the measured surface On the measured surface, different measured points on the measured surface reflect back light of different wavelengths, and the reflected light reaches the beam splitter (S3) again, and is divided by the beam splitter (S3) into two parallel beams of transmitted and reflected beams, in which the transmitted parallel beam is the same as that produced by The parallel light reflected by the plane mirror (M) reaches the beam splitter (S3) and is reflected by the beam splitter (S3) meet and interfere, each wavelength of light forms its own interference signal, and the interfering parallel beam reaches the beam splitter (S4), and is divided into two beams of parallel beams of transmission and reflection by the beam splitter (S4), and the transmission parallel beam is vertically incident on a parallel plate of the Fabry-Perot filter (X2), satisfying the coherence of the Fabry-Perot filter (X2) The light of the constructive condition wavelength can be transmitted, and the light of the comb-like wavelength whose adjacent wavelength interval is the free spectral region of the Fabry-Perot filter passes through the Fabry-Perot filter (X2), forming a comb-like shape with discontinuous cross-sectional light energy The parallel light beam is detected by the corresponding pixel of the area array detector (PD2), and the interference signal detected by the area array detector (PD2) is input to the computer (B5) after passing through the data acquisition card (B2), and the interference of this group of comb wavelengths The signal is formed by meeting the reflected light of a group of equally spaced points on the measured surface on the measured surface and the reflected light of the plane mirror (M), and the interference signal of each wavelength in the comb wavelength carries the corresponding measured point Longitudinal information; in order to measure other points, the translation stage (T2) drives a parallel plate of the Fabry-Perot filter (X2) to move, thereby adjusting the cavity length of the Fabry-Perot filter (X2), so that the other group meets The comb wavelength of the Fabry-Perot filter coherent and constructive conditions passes through and is detected by the area array detector (PD2), and the interference signal detected by the area array detector (PD2) is input to the computer (B5) after passing through the data acquisition card (B2) , the interference signal of this group of comb-shaped wavelengths is formed by the meeting of the reflected light of each point on the measured line with another set of equal intervals on the measured surface and the reflected light of the plane reflector (M). The interference signal of each wavelength carries the longitudinal information corresponding to the measured point; so repeated, so that the interference signal formed by the meeting of the reflected light of each measured point on the measured surface and the reflected light of the plane mirror (M) is surfaced The array detector (PD2) detects; the computer (B5) demodulates the interference signal, and realizes the full-field measurement of the surface where the longitudinal height difference between two adjacent measured points is not greater than half a wavelength, and the measurement result is output by the result (B6) Output: Due to the effect of the light-blocking screen P, the beam reflected from the beam splitter S1 cannot reach the interferometer, so it does not play a role in the measurement. At this time, only the beam transmitted from the beam splitter S1 reaches the interferometer and the measured surface, participating Complete the measurement work; for the measurement of the discontinuous surface of the steps and grooves where the longitudinal height difference of two adjacent measured points is greater than half a wavelength, at first, according to the above steps, the area array detector (PD2) detects every The interference signal formed by the reflected light of a measured point is input into the computer (B5) after the interference signal passes through the data acquisition card (B2), and then the light blocking screen (P) is moved to the beam transmitted from the beam splitter (S1) position (as shown in the figure, the position of the dotted line between the beam splitter (S1) and (S2)), the light blocking screen (P) blocks the beam transmitted from the beam splitter (S1), so that it does not participate in the measurement; by the beam splitter The light beam reflected by (S1) is diverted by right-angle prisms (R2) and (R3), then reaches the beam splitter (S2), and is passed by the beam splitter (S2) ) is divided into two beams of reflection and transmission, the transmission beam exits the measurement system, and the reflection beam is incident on the cylindrical convex lens ( On L4), it is focused on the back focus of the cylindrical convex lens (L4), because the back focus of the cylindrical convex lens (L4) is on the diffraction surface of the diffraction grating (G), so the light beam is focused on the diffraction grating (G) On the diffractive surface, the diffraction grating (G) is dispersed to form a fan-shaped light sheet with a continuous distribution of wavelengths in the lateral direction. This fan-shaped light sheet is collimated by a cylindrical convex lens (L5) into a parallel light sheet with continuous distribution of wavelengths in the lateral direction; The angle of incidence of this beam of light on the diffraction grating (G) is the same as the angle of incidence of the beam of light passing through the main optical axis of the cylindrical convex lens (L4) (beams transmitted from (S1) and (S2)) on the diffraction grating (G) Different, so the two wavelengths formed after the two beams of light are diffracted by the diffraction grating (G) are in the fan-shaped light sheets distributed in the horizontal direction, and each wavelength has different spatial positions in the two fan-shaped light sheets. After passing through the lens (L5) The collimated wavelengths are space-distributed parallel wave plates, and the positions of each wavelength are laterally misaligned in two parallel light plates. The parallel light plates are expanded by two confocal cylindrical convex lenses (L6) and (L7). Parallel light beam, this parallel light beam reaches the beam splitter (S3), and is divided into two beams of light, transmission and reflection, in which the transmitted parallel light is incident on the plane mirror (M), reflected by the plane mirror (M), and returns to the beam splitter again (S3), and then reflected and transmitted by the beam splitter (S3) into two parallel beams, the parallel beams reflected by the beam splitter (S3) are projected on the surface to be tested, and different measured points on the surface to be tested are reflected back to different wavelengths The reflected light reaches the beam splitter (S3) again, and is divided by the beam splitter (S3) into two beams of parallel light, transmission and reflection. The parallel light beams reflected by the mirror (S3) meet and interfere, each wavelength of light forms its own interference signal, and this interference parallel beam reaches the beam splitter (S4), and is divided into two parallel beams of transmission and reflection by the beam splitter (S4) , the transmitted light beam is vertically incident on a parallel plate of the Fabry-Perot filter (X2), the light satisfying the coherent and constructive condition of the Fabry-Perot filter (X2) can be transmitted, and the adjacent wavelength interval is the Fabry-Perot filter (X2) The comb-shaped wavelength light in the free spectrum region passes through the Fabry-Perot filter (X2), forming a comb-shaped parallel beam with discontinuous cross-sectional light energy, which is detected by the corresponding pixel of the area detector (PD2). The interference signal detected by the array detector (PD2) is input to the computer (B5) after passing through the data acquisition card (B2). The reflected light of the point meets the reflected light of the mirror (M), and the interference signal of each wavelength in the comb wavelength carries the longitudinal information corresponding to the measured point; in order to measure other points, the longitudinal translation stage (T3 ) drives a parallel plate of the Fabry-Perot filter (X2) to move, thereby adjusting the cavity length of the Fabry-Perot filter (X2), so that another group of combs that meet the coherent and constructive conditions of the Fabry-Perot filter (X2) The wavelength passes through and is detected by the area array detector (PD2). The interference signal detected by the area array detector (PD2) passes through the data acquisition card (B2) and then input to the computer (B5). The reflected light of each point on another set of equally spaced measured lines on the measured surface meets the reflected light of the plane mirror (M). Therefore, the interference signal of each wavelength in the comb wavelength carries the corresponding measured point Longitudinal information; so repeated, the interference signal formed by the meeting of the reflected light of each measured point on the measured surface and the reflected light of the plane mirror (M) is detected by the area array detector (PD2), and the area array The interference signal detected by the detector (PD2) is input to the computer (B5) after passing through the data acquisition card (B2); The surface of the groove is measured in full field, and the measurement result is output by the result output B6; the interference parallel beam reflected by the beam splitter (S4) reaches the slit diaphragm (D2), and each point of this light is an interference signal formed by a different wavelength. The interference signal passing through the slit diaphragm (D2) reaches the photodetector (PD1), and is detected by the photodetector (PD1). The control circuit (B4) processes, the output signal of the feedback control circuit (B4) is added to the piezoelectric ceramic (PZT) located in the reference arm of the interferometer, and the piezoelectric ceramic (PZT) is driven to adjust the optical path of the reference arm of the interferometer , keep the two interfering arms of the interferometer in an orthogonal state, thereby eliminating the influence of environmental interference on the interferometer, thereby achieving the purpose of stabilizing the measurement system and making the measurement system suitable for on-line measurement. 2. A kind of super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field according to claim 1, is characterized in that utilizes diffraction grating (G) dispersion broadband spectrum to form wavelength in lateral direction (perpendicular to light wave transmission direction ) Continuously distributed fan-shaped light sheet, expand the fan-shaped light sheet into a parallel beam, and the parallel beam is vertically incident on the surface to be measured, and the whole-field three-dimensional measurement is performed on the measured surface, and the surface three-dimensional measurement is completed in one positioning, and the measurement speed is fast . 3. A kind of super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field according to claim 1, characterized in that light of two wavelengths is used to measure the same measured point on the measured surface respectively , by demodulating the interference signals of these two wavelengths, the measurement system can perform three-dimensional measurement on the discontinuous surface of steps with a height difference greater than half a wavelength and grooves with a large aspect ratio. 4. A kind of super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field according to claim 1, characterized in that the wavelength is continuously distributed in the lateral direction and various wavelengths are formed by using the diffraction grating (G) dispersion broadband spectrum The parallel light beam with a constant spatial position enables the measurement results to be accurately traced to the wavelength reference, and the spectral drift of the light source has no effect on the measurement results. 5. A kind of super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field according to claim 1, it is characterized in that utilize Fabry-Perot filter (X2) to convert the parallel light beam of wavelength continuous distribution in lateral direction Comb-like parallel beams with discontinuous energy in the lateral direction to improve the lateral resolution in the direction of wavelength alignment. 6. A kind of super lateral resolution surface three-dimensional online interferometry system based on spectral dispersion full field according to claim 1, it is characterized in that the output signal utilizing feedback control circuit (B4) is added in the reference arm that is positioned at interferometer On the piezoelectric ceramic (PZT), the piezoelectric ceramic (PZT) is driven to adjust the optical path of the reference arm of the interferometer, so that the two interference arms of the interferometer are kept in an orthogonal state, thereby eliminating the influence of environmental interference on the interferometer, Improve the anti-interference ability of the measurement system, achieve the purpose of stabilizing the measurement system, and make the measurement system suitable for online measurement.