Interference confocal measurement system based on space coding and measurement method thereof

Abstract

The invention relates to the field of optical detection, in particular to an interference confocal measurement system based on space coding and a measurement method thereof.White light generated by a light source is collimated through a first collimating lens and then divided into S polarized light and P polarized light through a polarization splitting prism, the S polarized light enters a reference plane mirror through a first quarter-wave plate, and the P polarized light enters a second quarter-wave plate; p polarized light enters a blazed grating through a second quarter-wave plate for transverse dispersion and then is changed into monochromatic polarized light with different wavelengths and the same focal length through a first achromatic lens, and the monochromatic polarized light and the monochromatic polarized light are jointly focused at the same depth position of an object to be measured. Information of the object to be measured is carried and returned to the polarization splitting prism, two beams of polarized light are combined and then focused on a target surface of a photoelectric detector of an imaging spectrometer with a mask plate through a focusing lens, an interference image of the object to be measured is obtained, and spectrum and interference analysis is carried out. According to the invention, the transverse scanning speed can be improved, the measurement time can be shortened, and the resolution can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to an interference confocal measurement system based on spatial coding and a measurement method thereof. Background Art

[0002] In the field of modern precision measurement, the acquisition of three-dimensional surface topography is crucial for multiple application scenarios, especially in the production of tiny electronic components and tissue structure analysis in biomedicine. Traditional three-dimensional surface topography measurement methods, such as stylus profilometers, may damage samples due to their contact measurement methods, and it is difficult to obtain accurate measurement results on complex surfaces or soft materials. Therefore, non-contact optical measurement methods have gradually become the focus of research and application. Confocal microscopy occupies an important position in high-precision surface profile measurement due to its high axial and lateral resolution. However, although confocal microscopy has excellent resolution, it requires scanning samples point by point. This point scanning method results in a slow measurement speed and cannot meet the needs of rapid measurement of large-area samples. Its imaging speed is limited by the mechanical scanning process. This problem significantly affects its application in rapid measurement.

[0003] In order to overcome the speed limitation of traditional confocal microscopes, some innovative improvement schemes have emerged in recent years. Among them, the spectral confocal displacement sensor introduces a dispersion element and uses the chromatic aberration of the lens to produce light dispersion, so that light of different wavelengths is focused at different depths, eliminating the need for mechanical axial scanning. In this way, the spectral confocal displacement sensor technology not only improves the scanning speed, but also maintains high resolution and high precision, becoming an important breakthrough in three-dimensional surface measurement technology.

[0004] Although the existing spectral confocal displacement sensor technology has a high resolution in nanometer-level precision measurements, it still faces technical difficulties in practical applications. First, environmental factors such as temperature, humidity, vibration, etc. during the measurement process will have a significant impact on the measurement results. Especially in long-term measurements, the accuracy is easily plagued by drift and error accumulation. Secondly, under high-precision measurements, even a small displacement of the sample or a small deformation of the measurement system will cause significant errors and affect the reliability of the measurement results. In addition, spectral confocal displacement sensor technology mostly focuses on the improvement of the simple axial scanning speed, and rarely involves the improvement of the lateral scanning speed. Summary of the invention

[0005] In view of this, the present invention aims to provide an interferometric confocal measurement system and a measurement method thereof based on spatial encoding, so as to solve the problems of slow lateral scanning speed and limited measurement accuracy of spectral confocal displacement sensor technology.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: An interferometric confocal measurement system based on spatial encoding comprises a light source, a first collimating lens, a first quarter wave plate, a second quarter wave plate, a polarization beam splitter prism, a reference plane mirror, a first blazed grating, an aperture, a first achromatic lens, a translation stage, a focusing lens, a pinhole, a mask and an imaging spectrometer; wherein, The light source is used to emit white light; The first collimating lens is used to collimate the white light into parallel light; Polarization beam splitter is used to split parallel light into S polarized light and P polarized light. S polarized light is used as reference light and P polarized light is used as measurement light. The first quarter wave plate is used to convert the S polarized light used as the reference light into left circularly polarized light; The reference plane mirror is used to reflect the left-handed circularly polarized light, so that the left-handed circularly polarized light becomes right-handed circularly polarized light, and the right-handed circularly polarized light is converted into P-polarized light through the first quarter-wave plate and returns to the polarization beam splitter prism; The second quarter wave plate is used to convert the P polarized light used as the measuring light into right circular polarized light; The first blazed grating is used to disperse the right-handed circularly polarized light and decompose the right-handed circularly polarized light into monochromatic polarized lights of different wavelengths; The aperture is used to control the amount of monochromatic polarized light entering; The first achromatic lens is used to correct the chromatic aberration of monochromatic polarized light of different wavelengths, so that the focal points of the monochromatic polarized light of different wavelengths are the same and focused on the object to be measured at the same time, and then reflected by the surface of the object to be measured to become left-handed circularly polarized light, and then converted into S-polarized light by the second quarter-wave plate, and returned to the polarization beam splitter prism; The focusing lens is used to focus light of different polarization states; The pinhole is used to suppress out-of-focus light; The mask is used to allow light of different polarization states to interfere when passing through; The imaging spectrometer is used to measure the three-dimensional information of the object to be measured by adopting the principle of dispersive confocal interferometry; The translation stage is used to carry the object to be measured and drive the object to be measured to move in the x-direction and the y-direction. The x-direction is the depth direction of the object to be measured, and the y-direction is the longitudinal direction of the object to be measured.

[0007] Furthermore, the mask is composed of a micro-polarizer array.

[0008] Furthermore, the imaging spectrometer includes a second collimating lens, a second blazed grating, a second achromatic lens and a photodetector which are sequentially arranged along the light transmission direction.

[0009] A measurement method implemented by using the above-mentioned interferometric confocal measurement system based on spatial encoding comprises the following steps: S1: The translation stage drives the object to be measured to move along the y direction. Through the blazed grating and the first achromatic lens, the P-polarized light used as the measurement light is transformed into a row of monochromatic polarized lights with the same focal length and different wavelengths. The monochromatic polarized lights of different wavelengths interfere with the S-polarized light used as the reference light at the mask. The imaging spectrometer obtains 4 frames of interference images with a phase difference of π / 2 within one frame rate, and calculates the initial phase of the object to be measured. S2: Calculate the height value of the current layer of the object to be measured corresponding to each wavelength of monochromatic polarized light according to the initial phase of the object to be measured; S3: The translation stage drives the object to be measured to move along the x direction, repeating S1 and S2, calculating the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light, and obtaining the three-dimensional information of the object to be measured.

[0010] Furthermore, the obtained 4-frame interference images are:

[0011] in, , , , are the light intensities of the interference fringes in the four interference images; is the background light intensity of the interference image; is the modulation amplitude of the interference fringes; is the initial phase of the wavefront of the object to be measured; is the coordinate of the pixel point in the interference image; then:

[0012] Furthermore, the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light for:

[0013] in, It is monochromatic polarized light of different wavelengths.

[0014] Compared with the prior art, the invention can achieve the following beneficial effects: 1. The lateral encoding of the spectrum is achieved through the blazed grating and the achromatic lens, thereby increasing the lateral scanning speed, shortening the measurement time, and achieving rapid measurement of large-area objects without sacrificing accuracy.

[0015] 2. Combining lateral encoding of the spectrum with interference can provide higher sensitivity and resolution, thereby achieving higher resolution measurement of the object to be measured and making the detection of tiny structures more accurate.

[0016] 3. By adding a mask to the imaging spectrometer, each micro-polarizer of the mask is interfered, ensuring that all phase diagrams required to calculate the initial phase of the object to be measured are obtained within one frame rate, thereby avoiding measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 It is a structural schematic diagram of an interferometric confocal measurement system based on spatial encoding according to an embodiment of the invention; Figure 2 is a schematic structural diagram of an imaging spectrometer according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the confocal signal intensity in a non-interference measurement state at a single wavelength of about 450nm according to an embodiment of the invention; Figure 4 It is a schematic diagram of the interference signal intensity at a single wavelength of about 450nm according to an embodiment of the invention; Figure 5 It is a schematic diagram of the interference confocal signal intensity at a single wavelength of about 450nm according to an embodiment of the invention; Figure 6 It is a schematic diagram of the interference confocal signal intensity corresponding to different wavelengths after lateral encoding according to the embodiment of the invention.

[0018] Description of reference numerals: 1. Light source; 2. First collimating lens; 3. Polarization beam splitter; 4. Reference plane mirror; 5. First blazed grating; 6. Aperture; 7. First achromatic lens; 8. Object to be measured; 9. Translation stage; 10. Focusing lens; 11. Pinhole; 12. Mask; 13. Imaging spectrometer; 14. First quarter-wave plate; 15. Second quarter-wave plate; 16. Second collimating lens; 17. Second blazed grating; 18. Second achromatic lens; 19. Photodetector. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] The following will refer to Figure 1-Figure 6 The invention is described in detail with reference to the embodiments.

[0024] like Figure 1 As shown, the interferometric confocal measurement system based on spatial coding provided by the embodiment of the present invention includes a light source 1, a first collimating lens 2, a polarization beam splitter prism 3, a reference plane mirror 4, a first blazed grating 5, an aperture 6, a first achromatic lens 7, an object to be measured 8, a translation stage 9, a focusing lens 10, a pinhole 11, a mask 12, an imaging spectrometer 13, a first quarter wave plate 14, and a second quarter wave plate 15.

[0025] The description of each device is as follows: Light source 1: emits continuous broadband white light; The first collimating lens 2 is used to collimate the white light into parallel light; Polarization beam splitter prism 3: used to separate or combine light according to its polarization direction; when separating light, the light is divided into S polarized light and P polarized light, the S polarized light is used as reference light, and the P polarized light is used as measurement light; Reference plane mirror 4: used to increase the optical path difference; The first blazed grating 5 is used to separate monochromatic polarized light of different wavelengths to achieve transverse encoding; Aperture 6: used to control the amount of monochromatic polarized light entering; First achromatic lens 7: used to correct the chromatic aberration of monochromatic polarized light of different wavelengths, so that the focal points of monochromatic polarized light of different wavelengths are the same and focused to the same depth of the object to be measured; The translation stage 9 is used to carry the object to be measured 8 and drive the object to be measured 8 to move in the x direction and the y direction. The x direction is the depth direction of the object to be measured 8 (i.e., axial scanning), and the y direction is the longitudinal direction of the object to be measured (i.e., lateral scanning). The translation stage 9 can use a piezoelectric ceramic driver.

[0026] Focusing lens 10: used to focus light of different polarization states; Pinhole 11: used to suppress out-of-focus light and reduce the interference of scattered light; Mask 12: composed of a micro-polarizer array, used for causing interference between each micro-polarizer when light of different polarization states passes through, thereby generating a four-phase interference pattern image; Imaging spectrometer 13: used for imaging and analyzing the spectrum, adopting the principle of dispersive confocal interferometry to achieve three-dimensional information measurement of the object to be measured 8; The first quarter wave plate 14 and the second quarter wave plate 15 are used to convert linear polarized light into circular polarized light or to convert circular polarized light into linear polarized light. like Figure 2 As shown, the imaging spectrometer 13 includes a second collimating lens 16, a second blazed grating 17, a second achromatic lens 18 and a photodetector 19 which are sequentially arranged along the light transmission direction. The second collimating lens 16 is used to collimate the incident light into parallel light, and the second blazed grating 17 is used to separate light of different wavelengths to achieve lateral encoding; the second achromatic lens 18 is used to focus light of different wavelengths at the same position; the photodetector 19 is used to receive spectral information and perform photoelectric conversion, and the photodetector 19 can be a CCD detector or a CMOS detector.

[0027] The working principle of the interferometric confocal measurement system based on spatial encoding is as follows: the white light generated by the light source 1 is collimated into parallel light by the first collimating lens 2, and the parallel light is divided into S polarized light and P polarized light by the polarization beam splitter prism 3. The S polarized light is converted into left circular polarized light by the first quarter wave plate 14 and reaches the reference plane mirror 4, and is converted into right circular polarized light by reflection from the reference plane mirror 4, and then is converted into P polarized light by the first quarter wave plate 14, and returns to the polarization beam splitter prism 3 carrying the reference surface information, and the P polarized light is converted into right circular polarized light by the second quarter wave plate 15, and then is transversely dispersed by the first blazed grating 5, and is decomposed into different The monochromatic polarized light of different wavelengths passes through the aperture 6 and is corrected for chromatic aberration by the first achromatic lens 7, so that the focal lengths of the monochromatic polarized light of different wavelengths are the same, and they are focused on the same depth position of the object to be measured 8 together, and are reflected by the object to be measured 8 to become left-handed circularly polarized light, and then are converted into S polarized light by the second quarter wave plate 15, and return to the polarization beam splitter prism 3 with the information of the object to be measured, and the S polarized light and the P polarized light are combined and focused on the target surface of the photodetector of the imaging spectrometer 13 on which a mask 12 is placed through the focusing lens 10, and the interference image of the object to be measured 8 is obtained, and the spectrum and interference analysis are performed. The mobile displacement stage 9 drives the object to be measured 8 to move along the y direction to realize the lateral scanning of the current layer of the object to be measured 8. After the current layer is scanned, the mobile displacement stage 9 drives the object to be measured 8 to move along the x direction to realize the lateral scanning of the next layer of the object to be measured 8, until the lateral scanning of all layers is completed, and the three-dimensional information of the object to be measured 8 is obtained.

[0028] The present invention uses a blazed grating and an achromatic lens to expand the white light point source horizontally into a row of point light spots with different wavelengths and the same focal length, thereby realizing horizontal encoding. Combined with interferometry, interferometry occurs at each point light spot. Figure 3 As shown in, it is the signal intensity curve in the non-interference measurement state at a wavelength of about 450nm; Figure 4 As shown in, it is the signal intensity curve of the interference measurement at a wavelength of about 450nm; Figure 5 As shown in the figure, it is the signal intensity curve of the interference confocal at a wavelength of about 450nm. Figure 6 As shown, it is the signal intensity curve of the interference confocal corresponding to different wavelengths in the imaging spectrometer after transverse encoding. Figure 6 By solving each signal curve, all the height information of the object to be measured 8 in the horizontal direction can be obtained.

[0029] For the interference confocal curve at a single wavelength, S-polarized light and P-polarized light will interfere due to the different optical path differences, and the interference field is: ; in, is the optical path difference between the reflected light of the reference plane mirror 4 and the reflected light of the object to be measured 8. When the reference plane mirror 4 is assumed to be an ideal plane, The surface undulation of the object to be measured 8, that is, the height information is calculated.

[0030] In order to ask , it is necessary to introduce a controllable amount , rewrite the above formula as: ; in, is the background intensity of the interference pattern; is the modulation amplitude of the interference fringes; is the initial phase of the object 8 to be measured; is the shift phase value; It is the coordinate information of the pixel point in the interference pattern.

[0031] The interference signal is subjected to sinusoidal modulation with a short period length. At least three points must be collected in each period to obtain relatively reliable data information and effective data processing. The coherence peak addressing method is proposed based on the characteristics of short coherence length and obvious coherence peak of white light signal: taking two points of different heights as an example, coherence peaks appear successively at the two points during the scanning measurement process. The position of the peak value of the coherence peak is used as a reference, and the difference between the peak values ​​of the two coherence peaks on the Z axis is the height difference between the two points. The present invention uses a four-step phase shift method to solve the problem.

[0032] The four-step phase shifting method can effectively calculate the phase distribution of the ideal phase shifting diagram group. However, the traditional four-step phase shifting method needs to control the piezoelectric ceramic driver to move the objective lens position, so that the optical path difference between the reference light and the object light changes, and the phase shift amount changes in the time sequence. This time-domain phase-shift interferometer has a problem that cannot be ignored: each light intensity map required for calculation is obtained at different times. Usually the CCD frame rate is 30 frames / s, but the calculation Generally, 5 to 13 frames of interference images are required, and the total measurement time is about 200 to 400ms. This introduces a series of errors. For example, any changes in the optical path caused by the environment during the phase shift measurement (vibration, air disturbance, etc.) will cause measurement errors. In order to solve this problem, it is necessary to obtain all phase images required to complete the calculation within one frame rate of the CCD. Therefore, the present invention adds a mask 12 above the imaging spectrometer 13. The number and position of the micropolarizers in the mask 12 correspond to the pixels of the CCD one by one, so that light of different polarization states interferes when passing through each micropolarizer of the mask 12, and the phases of interference at different positions are different, so that any group of adjacent 4 pixels have interference with a fixed phase difference; after entering the imaging spectrometer 13, 4 frames of interference images with a phase difference of π / 2 can be obtained within one frame rate.

[0033] The following four formulas are obtained through 4 frames of interference images:

[0034] in, , , , are the light intensities of the interference fringes in the four interference images; is the background light intensity of the interference image; is the modulation amplitude of the interference fringes; is the initial phase of the object to be measured.

[0035] The initial phase of the object 8 to be measured can be calculated by transforming the four formulas and eliminating A and B. : .

[0036] In the case of single-wavelength interferometry, the calculated phase is usually a wrapped phase in the range [-π,π]. If the measured optical path difference is within a wavelength range (i.e., the optical path difference is less than a single wavelength), the phase will not jump, and accurate measurement results can be obtained directly using the wrapped phase. Finally, the height at a single wavelength is calculated using the following formula: ; in, is the wavelength at the corresponding position of the object 8 to be measured.

[0037] Request That is, the height value of the object to be measured 8 at a certain wavelength point in the current layer in the horizontal coding. By calculating the entire spectrum, all height values ​​of the object to be measured 8 in the current layer can be obtained. The translation stage 9 drives the object to be measured 8 to move, so that the polarized light is focused to the next layer of the object to be measured 8, and all height values ​​of the next layer are measured, and finally the three-dimensional information of the object to be measured is obtained.

[0038] The technical effect of the present invention is described by taking an example. Scan the object 8 horizontally in the x and y directions and take 100 scanning points respectively. , At the same time, 50 scanning points are taken in the z direction of the axial scanning of the object to be measured 8 Each movement of the translation stage 9 takes t=0.1s, and the measurement time is negligible relative to the movement time.

[0039] The time required for traditional point scanning is The present invention uses the transverse encoding method of the line light source and combines the axial dispersion principle, and can simultaneously measure all scanning points in the x direction, that is, reduce the scanning in the x direction and only scan in the y and z directions. The scanning time is 500s , therefore, the scanning time required by the present invention is greatly reduced.

[0040] At the same time, the traditional point confocal microscope is simulated, using a Gaussian beam with a wavelength of 633nm and a radius of 2.24mm, and the high NA objective lens is 0.9. The axial resolution is 203nm. In the present invention, the dispersion interference method is used for calculation. When the wavelength and radius of the Gaussian beam remain unchanged, the dispersion lens uses typical BK7 glass with a moderate dispersion coefficient of about 0.0103nm. - ¹ mm - ¹, the focal length is 98mm. The dispersion effect will cause the focus position of beams of different wavelengths to shift to different degrees. The impact of axial resolution can be estimated by the dispersion of the optical system, and its axial resolution is 654nm. This is due to the focus shift introduced by the dispersion lens, and the accuracy drops by about 222%.

[0041] Although the dispersion lens introduces a certain degree of accuracy reduction, resulting in a decrease in axial resolution relative to the traditional confocal microscope system, its advantage in measurement speed is obvious. From the previous calculations, it can be seen that the present invention significantly reduces the scanning time. Although the accuracy is reduced, this reduction in accuracy is acceptable for many high-speed scanning and dynamic process monitoring scenarios, especially when it is necessary to quickly obtain three-dimensional morphological information.

[0042] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0043] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An interferometric confocal measurement system based on spatial encoding, characterized in that: It includes a light source, a first collimating lens, a first quarter wave plate, a second quarter wave plate, a polarization beam splitter, a reference plane mirror, a first blazed grating, an aperture, a first achromatic lens, a translation stage, a focusing lens, a pinhole, a mask and an imaging spectrometer; wherein, The light source is used to emit white light; The first collimating lens is used to collimate the white light into parallel light; Polarization beam splitter is used to split parallel light into S polarized light and P polarized light. S polarized light is used as reference light and P polarized light is used as measurement light. The first quarter wave plate is used to convert the S polarized light used as the reference light into left circularly polarized light; The reference plane mirror is used to reflect the left-handed circularly polarized light, so that the left-handed circularly polarized light becomes right-handed circularly polarized light, and the right-handed circularly polarized light is converted into P-polarized light through the first quarter-wave plate and returns to the polarization beam splitter prism; The second quarter wave plate is used to convert the P polarized light used as the measuring light into right circular polarized light; The first blazed grating is used to disperse the right-handed circularly polarized light and decompose the right-handed circularly polarized light into monochromatic polarized lights of different wavelengths; The aperture is used to control the amount of monochromatic polarized light entering; The first achromatic lens is used to correct the chromatic aberration of monochromatic polarized light of different wavelengths, so that the focal points of the monochromatic polarized light of different wavelengths are the same and focused on the object to be measured at the same time, and then reflected by the surface of the object to be measured to become left-handed circularly polarized light, and then converted into S-polarized light by the second quarter-wave plate, and returned to the polarization beam splitter prism; The focusing lens is used to focus light of different polarization states; The pinhole is used to suppress out-of-focus light; The mask is used to cause interference when light of different polarization states passes through; The imaging spectrometer is used to measure the three-dimensional information of the object to be measured by adopting the principle of dispersive confocal interferometry; The translation stage is used to carry the object to be measured and drive the object to be measured to move in the x-direction and the y-direction. The x-direction is the depth direction of the object to be measured, and the y-direction is the longitudinal direction of the object to be measured.

2. The interferometric confocal measurement system based on spatial encoding according to claim 1, characterized in that: The mask is made of an array of micro-polarizers.

3. The interferometric confocal measurement system based on spatial encoding according to claim 1, characterized in that: The imaging spectrometer comprises a second collimating lens, a second blazed grating, a second achromatic lens and a photodetector which are sequentially arranged along the light transmission direction.

4. A measurement method implemented by the interferometric confocal measurement system based on spatial encoding according to claim 1, characterized in that: The steps include: S1: The translation stage drives the object to be measured to move along the y direction. Through the blazed grating and the first achromatic lens, the P-polarized light used as the measurement light is transformed into a row of monochromatic polarized lights with the same focal length and different wavelengths. The monochromatic polarized lights of different wavelengths interfere with the S-polarized light used as the reference light at the mask. The imaging spectrometer obtains 4 frames of interference images with a phase difference of π / 2 within one frame rate, and calculates the initial phase of the object to be measured. S2: Calculate the height value of the current layer of the object to be measured corresponding to each wavelength of monochromatic polarized light according to the initial phase of the object to be measured; S3: The translation stage drives the object to be measured to move along the x direction, repeating S1 and S2, calculating the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light, and obtaining the three-dimensional information of the object to be measured.

5. The measuring method according to claim 4, characterized in that: The 4 interferometric images obtained are: in, , , , are the light intensities of the interference fringes in the four interference images; is the background light intensity of the interference image; is the modulation amplitude of the interference fringes; is the initial phase of the wavefront of the object to be measured; is the coordinate of the pixel point in the interference image; then:

6. The measuring method according to claim 5, characterized in that: The height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light for: in, It is monochromatic polarized light of different wavelengths.

Images