Interferometric confocal measurement system based on spatial encoding and its measurement method

Abstract

The present invention relates to the field of optical detection, and in particular to an interferometric confocal measurement system and method based on spatial encoding. White light generated by a light source is collimated by a first collimating lens and then separated into S-polarized light and P-polarized light by a polarization beam splitter prism. The S-polarized light is incident on a reference plane mirror via a first quarter-wave plate and returns to the polarization beam splitter prism carrying information about the reference surface. The P-polarized light is incident on a blazed grating via a second quarter-wave plate for lateral dispersion and then converted by a first achromatic lens into monochromatic polarized light of different wavelengths and the same focal length. The two beams are focused together at the same depth position of an object to be measured and return to the polarization beam splitter prism carrying information about the object to be measured. The two polarized light beams are combined and focused by a focusing lens onto the target surface of a photodetector of an imaging spectrometer on which a mask is placed, thereby obtaining an interference image of the object to be measured and performing spectral and interferometric analysis. The present invention can increase lateral scanning speed, shorten measurement time, and improve resolution.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to an interferometric 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 the sample due to their contact measurement method, 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 microscopes occupy an important position in high-precision surface profile measurement due to their high axial and lateral resolution. However, although confocal microscopes have excellent resolution, they need to scan the sample point by point. This point scanning method results in a slow measurement speed and cannot meet the needs of fast measurement of large-area samples. Its imaging speed is limited by the mechanical scanning process. This problem significantly affects its application in fast measurement.

[0003] To overcome the speed limitations of traditional confocal microscopes, several innovative improvements have emerged in recent years. Among them, the spectral confocal displacement sensor incorporates a dispersive element, exploiting the chromatic aberration of the lens to produce light dispersion. This allows light of different wavelengths to be focused at different depths, eliminating the need for mechanical axial scanning. This technology not only increases scanning speed while maintaining high resolution and precision, but also represents a significant breakthrough in 3D surface measurement technology.

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

[0007] An interferometric confocal measurement system based on spatial coding 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,

[0008] The light source is used to emit white light;

[0009] The first collimating lens is used to collimate the white light into parallel light;

[0010] Polarization beam splitter prism 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.

[0011] The first quarter-wave plate is used to convert the S-polarized light used as the reference light into left-handed circularly polarized light;

[0012] The reference plane mirror is used to reflect the left-handed circularly polarized light, turning it into right-handed circularly polarized light. The right-handed circularly polarized light is then converted into P-polarized light by the first quarter-wave plate and returns to the polarization beam splitter prism.

[0013] The second quarter-wave plate is used to convert the P-polarized light used as the measurement light into right-handed circularly polarized light;

[0014] The first blazed grating is used to disperse the right-handed circularly polarized light and decompose it into monochromatic polarized lights of different wavelengths;

[0015] The aperture is used to control the amount of monochromatic polarized light entering;

[0016] 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. The light is then reflected from the surface of the object to be measured and converted into left-handed circularly polarized light. The light is then converted into S-polarized light by the second quarter-wave plate and returns to the polarization beam splitter prism.

[0017] The focusing lens is used to focus light of different polarization states;

[0018] The pinhole is used to suppress out-of-focus light;

[0019] The mask is used to cause interference when light of different polarization states passes through it;

[0020] The imaging spectrometer is used to measure the three-dimensional information of the object to be measured using the principle of dispersive confocal interferometry;

[0021] 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.

[0022] Furthermore, the mask is composed of a micro-polarizer array.

[0023] 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.

[0024] A measurement method implemented using the above-mentioned interferometric confocal measurement system based on spatial encoding comprises the following steps:

[0025] S1: The translation stage moves the object to be measured in the y-direction. The blazed grating and the first achromatic lens transform the P-polarized light used as the measurement light into a row of monochromatic polarized lights with the same focal length but 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 four interference images with a phase difference of π / 2 within one frame rate, and calculates the initial phase of the object to be measured.

[0026] S2: Calculate the height value of the current layer of the object under test corresponding to each wavelength of monochromatic polarized light according to the initial phase of the object under test;

[0027] S3: The translation stage drives the object to be measured to move along the x-direction, repeating S1 and S2 to calculate the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light, and obtain the three-dimensional information of the object to be measured.

[0028] Furthermore, the four interference images obtained are:

[0029]

[0030] in, 、 、 、 are the light intensities of the interference fringes in the four frames of 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:

[0031]

[0032] Furthermore, the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light for:

[0033]

[0034] in, It is monochromatic polarized light of different wavelengths.

[0035] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0036] 1. The blazed grating and achromatic lens are used to achieve transverse encoding of the spectrum, thereby increasing the transverse scanning speed, shortening the measurement time, and achieving rapid measurement of large-area objects without sacrificing accuracy.

[0037] 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.

[0038] 3. By adding a mask to the imaging spectrometer, each micropolarizer of the mask interferes, ensuring that all phase maps required to calculate the initial phase of the object under test are obtained within a single frame rate, thereby avoiding measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 2 is a schematic structural diagram of an interferometric confocal measurement system based on spatial encoding according to an embodiment of the present invention;

[0041] Figure 2 2 is a schematic structural diagram of an imaging spectrometer according to an embodiment of the present invention;

[0042] Figure 3 2. This is a schematic diagram of the confocal signal intensity in a non-interference measurement state at a single wavelength of about 450 nm according to an embodiment of the present invention;

[0043] Figure 4 2. This is a schematic diagram of the interference signal intensity at a single wavelength of about 450 nm according to an embodiment of the present invention;

[0044] Figure 5 2. This is a schematic diagram of the interferometric confocal signal intensity at a single wavelength of about 450 nm according to an embodiment of the present invention;

[0045] Figure 6 2 is a schematic diagram of the interferometric confocal signal intensities corresponding to different wavelengths after transverse encoding according to an embodiment of the present invention.

[0046] Description of reference numerals:

[0047] 1. Light source; 2. First collimating lens; 3. Polarization beam splitter; 4. Reference plane mirror; 5. First blazed grating; 6. Aperture stop; 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

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0049] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0050] 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 orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like 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.

[0051] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0052] The following will refer to Figures 1-6 The present invention is described in detail with reference to the embodiments.

[0053] 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.

[0054] The description of each device is as follows:

[0055] Light source 1: emits continuous broadband white light;

[0056] First collimating lens 2: used to collimate white light into parallel light;

[0057] Polarization beam splitter 3: used to separate or combine light according to its polarization direction; when separating light, it is divided into S-polarized light and P-polarized light, with S-polarized light serving as reference light and P-polarized light serving as measurement light;

[0058] Reference plane mirror 4: used to increase the optical path difference;

[0059] The first blazed grating 5 is used to separate monochromatic polarized light of different wavelengths to achieve transverse encoding;

[0060] Aperture 6: used to control the amount of monochromatic polarized light entering;

[0061] First achromatic lens 7: used to correct the chromatic aberration of monochromatic polarized light of different wavelengths so that the monochromatic polarized light of different wavelengths has the same focal point and focuses on the same depth of the object to be measured;

[0062] The translation stage 9 is used to carry the object 8 to be measured and drive the object 8 to move in the x-direction and y-direction. The x-direction is the depth direction of the object 8 to be measured (i.e., axial scanning), and the y-direction is the longitudinal direction of the object to be measured (i.e., transverse scanning). The translation stage 9 can use a piezoelectric ceramic driver.

[0063] Focusing lens 10: used to focus light of different polarization states;

[0064] Pinhole 11: used to suppress out-of-focus light and reduce the interference of scattered light;

[0065] Mask 12: composed of a micro-polarizer array, used to cause interference between each micro-polarizer when light of different polarization states passes through, generating a four-phase interference pattern image;

[0066] Imaging spectrometer 13: used for imaging and analyzing the spectrum, using the principle of dispersive confocal interferometry to achieve three-dimensional information measurement of the object to be measured 8;

[0067] The first quarter wave plate 14 and the second quarter wave plate 15 are used to convert linearly polarized light into circularly polarized light or convert circularly polarized light into linearly polarized light.

[0068] 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 arranged in sequence 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. The photodetector 19 can be a CCD detector or a CMOS detector.

[0069] 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-handed circularly polarized light by the first quarter-wave plate 14 and reaches the reference plane mirror 4. It is reflected by the reference plane mirror 4 and converted into right-handed circularly polarized light. It then passes through the first quarter-wave plate 14 and becomes P-polarized light, carrying the reference surface information back to the polarization beam splitter prism 3. The P-polarized light is converted into right-handed circularly polarized light by the second quarter-wave plate 15, and then is transversely dispersed by the first blazed grating 5 to be decomposed into different Monochromatic polarized light of different wavelengths passes through aperture 6 and undergoes chromatic aberration correction via first achromatic lens 7, ensuring that the focal lengths of the monochromatic polarized light of different wavelengths are the same and that they are focused together at the same depth position of the object to be measured 8. After being reflected by the object to be measured 8, the light is converted into left-handed circularly polarized light. It is then converted into S-polarized light by second quarter-wave plate 15 and returns to polarization beam splitter 3, carrying information about the object to be measured. The S-polarized light is then combined with the P-polarized light and focused by focusing lens 10 onto the target surface of the photodetector of imaging spectrometer 13, on which a mask 12 is placed. An interference image of the object to be measured 8 is obtained for spectral and interferometric analysis. The movable translation stage 9 drives the object to be measured 8 to move in the y-direction, performing a lateral scan of the current layer of the object to be measured 8. After the current layer is scanned, the movable translation stage 9 drives the object to be measured 8 to move in the x-direction, performing a lateral scan of the next layer of the object to be measured 8, until all layers are scanned laterally, obtaining three-dimensional information about the object to be measured 8.

[0070] 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, achieving horizontal encoding. Combined with interferometry, interferometry occurs at each point light spot. Figure 3 As shown in the figure, 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 The following 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.

[0071] 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:

[0072] ;

[0073] 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 The surface undulation of the object to be measured 8, ie, height information, is calculated.

[0074] In order to seek , it is necessary to introduce a controllable amount , rewrite the above formula as:

[0075] ;

[0076] in, is the background intensity of the interference pattern; is the modulation amplitude of the interference fringes; is the initial phase of the object to be measured 8; is the shift phase value; It is the coordinate information of the pixel point in the interference pattern.

[0077] The interference signal is sinusoidally modulated with a short periodicity. At least three points must be collected within each period to obtain relatively reliable data and effective data processing. The coherence peak addressing method is based on the short coherence length and distinct coherence peak characteristics of white light signals. For example, during the scanning measurement process, coherence peaks appear at two points at different heights. The difference between the two coherence peaks on the Z axis, with the peak position of the coherence peaks as a reference, is the height difference between the two points. This invention uses a four-step phase shifting method to solve this problem.

[0078] 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 requires controlling 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 the 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 one-to-one to the pixels of the CCD, so that light with different polarization states interferes when passing through each micropolarizer of the mask 12, and the phase of interference at different positions is different, so that any group of 4 adjacent 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.

[0079] The following four formulas are obtained through 4 frames of interference images:

[0080]

[0081] in, 、 、 、 are the light intensities of the interference fringes in the four frames of 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.

[0082] The initial phase of the object 8 can be calculated by transforming the four formulas and eliminating A and B. :

[0083] .

[0084] 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 the wrapped phase can be used directly to obtain accurate measurement results. Finally, the height at a single wavelength is calculated using the following formula:

[0085] ;

[0086] in, is the wavelength at the corresponding position of the object to be measured 8.

[0087] What you want This is the height value of the object 8 under test at a certain wavelength point in the current layer during the horizontal encoding. By calculating the entire spectrum, all height values ​​of the object 8 under test in the current layer can be obtained. The translation stage 9 drives the object 8 under test, focusing the polarized light onto the next layer of the object 8 under test, completing the measurement of all height values ​​of the next layer, and ultimately obtaining the three-dimensional information of the object under test.

[0088] The technical effect of the present invention is described with an example. Scan the object 8 horizontally in the x and y directions and take 100 scanning points each. , 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.

[0089] The time required for traditional point scanning is 50000s. The present invention uses the transverse encoding method of the line light source and combines the axial dispersion principle. It can measure all the scanning points in the x direction at the same time, that is, reduce the scanning in the x direction and only perform the scanning in the y and z directions. The scanning time is 500s , therefore the scanning time required by the present invention is greatly reduced.

[0090] At the same time, a traditional point confocal microscope was simulated using a Gaussian beam with a wavelength of 633nm and a radius of 2.24mm. The axial resolution was calculated to be 203nm under the condition of a high NA objective lens of 0.9. In the present invention, the calculation was performed using the dispersion interferometry method. 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 varying degrees. The impact of axial resolution can be estimated by the dispersion of the optical system. The axial resolution is 654nm. This is due to the focus shift introduced by the dispersive lens, and the accuracy drops by about 222%.

[0091] Although the dispersion lens introduces a certain degree of precision loss, resulting in a lower axial resolution compared to traditional confocal microscope systems, its advantage in measurement speed is obvious. As shown in the previous calculations, the present invention significantly reduces scanning time. Although precision is reduced, this reduction in accuracy is acceptable for many high-speed scanning and dynamic process monitoring scenarios, especially when rapid acquisition of 3D topography information is required.

[0092] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0093] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. An interferometric confocal measurement system based on spatial encoding, characterized in that: The device comprises 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 prism 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-handed circularly polarized light; The reference plane mirror is used to reflect the left-handed circularly polarized light, turning it into right-handed circularly polarized light. The right-handed circularly polarized light is then converted into P-polarized light by 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 measurement light into right-handed circularly polarized light; The first blazed grating is used to disperse the right-handed circularly polarized light and decompose it 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. The light is then reflected from the surface of the object to be measured and converted into left-handed circularly polarized light. The light is then converted into S-polarized light by the second quarter-wave plate and returns 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 it; The imaging spectrometer is used to measure the three-dimensional information of the object to be measured using 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 composed of an array of micropolarizers.

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 moves the object to be measured in the y-direction. The blazed grating and the first achromatic lens transform the P-polarized light used as the measurement light into a row of monochromatic polarized lights with the same focal length but 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 four 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 under test corresponding to each wavelength of monochromatic polarized light according to the initial phase of the object under test; S3: The translation stage drives the object to be measured to move along the x-direction, repeating S1 and S2 to calculate the height value of each layer of the object to be measured corresponding to each wavelength of monochromatic polarized light, and obtain the three-dimensional information of the object to be measured.

5. The measuring method according to claim 4, characterized in that The four interference images obtained are: in, 、 、 、 are the light intensities of the interference fringes in the four frames of 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