Spectrum confocal three-dimensional shape measurement method and system based on area light source

Abstract

The invention provides a spectrum confocal three-dimensional shape measurement method and system based on an area light source, and belongs to the technical field of optical measurement, and the method comprises the steps: employing a Micro LED area light source capable of line-by-line driving to generate RGB three-color modulated isoenergetic white light, and after collimation and beam splitting of a beam splitter prism, the isoenergetic white light is converted into a light source; and the dispersion objective lens axially focuses light rays with different wavelengths at different height positions on the surface of a measured object. The reflected light is reflected to the array slit through the beam splitter prism and is split by the diffraction grating to form a spectral image containing space-wavelength two-dimensional information, and the surface height is analyzed by using a peak wavelength-height mapping relation. Full-field scanning is achieved by switching the area light sources line by line, and three-dimensional shape reconstruction can be completed without mechanical movement. The invention has the advantages of high light source brightness, high light source uniformity, uniform energy distribution of each wavelength, high scanning speed and high spatial resolution.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and in particular to a method and system for measuring three-dimensional topography based on a surface light source and spectral confocalization. Background Technology

[0002] Spectral confocal microscopy is a high-precision optical measurement technique that combines the spatial resolution of confocal imaging with the spectral resolution of spectral analysis. It enables non-contact measurement of parameters such as surface morphology and thickness, and is widely used in materials science, biomedicine, and industrial inspection.

[0003] A confocal system based on line illumination and mechanical scanning uses a cylindrical mirror or laser beam expander to convert a point source into high-energy, broadband white light. This light is then used to form a line measurement spot through a dispersive lens. The measurement spot reflects light of different wavelengths at different heights on the surface of the object being measured. This light is transmitted to a slit via a beam splitter. The focused light passing through the slit is then split and focused, forming an image on the detector. The peak wavelength is calculated and decoded into the height information of the object. A displacement platform drives the sample to move continuously along a direction orthogonal to the line spot, achieving area scanning of the object. This method is suitable for large field-of-view detection scenarios, but it is limited by mechanical inertia, resulting in slow imaging speed and positioning errors. The measurement accuracy depends on the accuracy of the mechanical positioning.

[0004] The surface spectral confocal system based on a Digital Micromirror Device (DMD) employs spatial light modulation technology. By setting the state of each micromirror to "ON" row by row, it achieves lateral movement of a linear illumination beam across the surface of the object under test, resulting in a full-field scanning effect. Compared to mechanical scanning schemes, it offers a higher scanning rate and avoids positioning errors and system vibration problems caused by mechanical inertia. However, this technology has three drawbacks: First, the DMD and its drive controller are costly. Second, a dedicated illumination optical path needs to be developed, leading to complex system integration. Finally, due to the limitations of the DMD device characteristics, only reflected light in the "ON" state participates in effective imaging, while reflected light in the "OFF" state forms stray light, which, combined with the transmission loss of the optical system, results in low system light energy utilization. Summary of the Invention

[0005] This invention provides a method and system for measuring three-dimensional topography based on a surface light source using spectral confocal imaging, in order to address at least one deficiency in the prior art.

[0006] In a first aspect, the present invention provides a method for measuring three-dimensional topography based on spectral confocal illumination using a surface light source, comprising: Step 101: Equal-energy white light with constant spectral energy density is emitted line by line through a surface light source, and then enters the beam splitter after being collimated by the first collimating lens; Step 102: The beam splitter transmits part of the collimated light to the dispersive objective lens, which converges light of different wavelengths at different positions on the optical axis of the dispersive objective lens. The converged light shines on the surface of the object being measured and is reflected. Step 103: The light beam reflected by the object under test returns to the beam splitter after passing through the dispersive objective lens. Part of the light beam is reflected by the beam splitter to the first focusing lens, and after being focused, it is projected onto one of the slits of the array slits. Step 104: After the light beam passing through the slit is subjected to beam splitting and imaging, a two-dimensional spectral image is obtained; the two-dimensional spectral image includes spatial location information and corresponding wavelength information; Step 105: Based on the spatial position information and wavelength information of the two-dimensional spectral image, obtain the height information of each point on the scanning line of the surface of the object under test; Step 106: By switching the light emission rows of the surface light source line by line, repeat steps 101 to 105 to complete the scanning of the entire surface of the object under test and obtain the three-dimensional shape of the entire surface of the object under test.

[0007] According to the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, the surface light source is a Micro LED surface light source, which includes an independently driveable RGB three-color pixel array.

[0008] According to the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, step 101 includes: adjusting the RGB three-color driving voltage of the Micro LED surface light source to generate equal-energy white light with uniform distribution of light energy of each wavelength.

[0009] According to the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, in step 104, the light beam passing through the slit is imaged by beam splitting to obtain a two-dimensional spectral image, which includes: the light beam passing through the slit is collimated by a second collimating lens; the light collimated by the second collimating lens is split by a diffraction grating and then passes through a second focusing lens to obtain a two-dimensional spectral image by a detector.

[0010] According to the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, step 105 includes: determining the height information of points on the scan line based on the peak wavelength corresponding to the spatial position information of the two-dimensional spectral image; wherein, the spatial position information of the two-dimensional spectral image and the points on the scan line have a one-to-one mapping relationship.

[0011] According to the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, the ratio of transmitted to reflected light by the beam splitter is 1:1.

[0012] The three-dimensional topography measurement method based on a surface light source provided by the present invention further includes, before determining the height information of points on the scan line according to the peak wavelength corresponding to the spatial position information of the two-dimensional spectral image, calibrating the mapping relationship between the wavelength and the height of the surface of the object being measured, so as to determine the height information of the surface of the object being measured according to the wavelength peak.

[0013] Secondly, the present invention also provides a spectral confocal three-dimensional topography measurement system based on a surface light source, comprising: A surface light source used to emit equal-energy white light with a constant spectral energy density line by line; The first collimating lens is located on the light-emitting path of the surface light source and is used to collimate the emitted light rays; The beam-splitting prism receives light rays that have been collimated by the first collimating lens and transmits a portion of the light rays to the dispersive objective lens. A dispersive objective lens is disposed on the transmission optical path of the beam splitter to focus light of different wavelengths at different positions on its optical axis, thereby forming a converging illumination on the surface of the object under test and receiving the reflected light from the surface of the object under test. The first focusing lens is located in the reflected light path of the beam splitter and is used to focus the light rays that return from the dispersive objective and are reflected by the beam splitter. An array of slits, disposed on the focal plane of the first focusing lens, is used to receive the focused light beam and pass it through one of the slits; The beam splitting and imaging module is used to split and image the light beam passing through the slit to obtain a two-dimensional spectral image containing spatial location information and wavelength information; the two-dimensional spectral image includes spatial location information and corresponding wavelength information. The processing module is used to calculate the height information of each point on the scanning line of the surface of the object under test based on the peak wavelength corresponding to the spatial position information in the two-dimensional spectral image, and to complete the reconstruction of the three-dimensional morphology of the entire surface by switching the light emission rows of the surface light source line by line.

[0014] According to the spectral confocal three-dimensional topography measurement system based on a surface light source provided by the present invention, the surface light source is a Micro LED surface light source, which includes an independently driveable RGB three-color pixel array.

[0015] According to the spectral confocal three-dimensional topography measurement system based on a surface light source provided by the present invention, the spectroscopic imaging module includes: The second collimating lens is used to collimate the light beam passing through the slit; A diffraction grating, located in the output light path of the second collimating lens, is used to split the collimated beam. The second focusing lens, located in the outgoing light path of the diffraction grating, is used to focus the split beam onto the detector. A detector is used to receive a focused beam of light and form a two-dimensional spectral image.

[0016] The spectral confocal three-dimensional topography measurement method and system based on a surface light source provided by this invention has the advantages of high light source brightness, high light source uniformity, uniform energy distribution across wavelengths, fast scanning speed, and high spatial resolution. Compared with linear illumination plus mechanical scanning, it eliminates the instability of mechanical motion and achieves higher resolution; compared with DMD for achieving lateral movement of the illumination beam, it has higher light source brightness, a simpler system, and higher light energy utilization. Specific beneficial effects are analyzed as follows: (1) Fast measurement speed. By illuminating one row of the surface light source (which can be a Micro LED surface light source), information of one line can be obtained in a single operation. By switching different rows of the surface light source, the three-dimensional shape information of the object under test can be quickly obtained, which solves the problem of slow imaging speed of the confocal system based on linear illumination and mechanical scanning. (2) High system stability. Compared with the movement of objects on a displacement stage, the stability of controlling the movement of the beam by lighting up the Micro LED surface light source in different rows is better, which can meet the needs of modern industrial production and scientific research for rapid and stable measurement.

[0017] (3) High measurement accuracy. Based on the different rows of the Micro LED surface light source to realize beam movement, continuous line illumination of the surface of the object being measured can be achieved, and the spatial resolution can reach the micrometer level, which solves the problem that the sensitivity and resolution of the existing technology need to be improved.

[0018] (4) Simple structure and low cost. Line illumination at different positions is achieved based on Micro LED surface light source, which is simpler and lower in cost than the complex DMD micro-mirror array structure, and solves the problems of complex system integration and high cost of surface spectral confocal system based on digital micromirror device.

[0019] (5) High light energy utilization. As a surface light source, Micro LED can participate in imaging with light emitted from each row, and there is no stray light problem. It has high light energy utilization, which solves the problem of low light energy utilization in surface spectral confocal systems based on digital micromirror devices. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1This is a flowchart illustrating the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention. Figure 2 This is a schematic diagram of the structure of the spectral confocal three-dimensional topography measurement system based on a surface light source provided by the present invention; Figure 3 This is a schematic diagram of spectral imaging using a spectral imaging module provided by the present invention; Figure 4 This is a schematic diagram of a two-dimensional spectral image provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] It should be noted that, in the description of the embodiments of the present invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0024] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more.

[0025] The following is combined with Figures 1-4 This invention describes the method and system for measuring three-dimensional topography based on a surface light source using spectral confocal imaging, as provided in the embodiments of the present invention.

[0026] Figure 1 This is a flowchart illustrating the spectral confocal three-dimensional topography measurement method based on a surface light source provided by the present invention, as shown below. Figure 1 As shown, including but not limited to the following steps: Step 101: Equal-energy white light with constant spectral energy density is emitted line by line through a surface light source, and then enters the beam splitter after being collimated by the first collimating lens.

[0027] This invention uses a surface light source (such as an LED array or fiber optic panel) to replace the traditional point light source, and achieves large-area, uniform illumination of the surface of the object being measured through row-by-row emission control.

[0028] In one embodiment, the present invention may select a Micro LED surface light source, which includes an independently driveable RGB three-color pixel array. The following is a detailed description: Micro LED is an emerging self-emissive display technology that uses micron-sized (1-100µm) light-emitting diodes. Red (R), green (G), and blue (B) LED chips are precisely arranged and integrated on a driver backplane, enabling independent brightness and color control for each pixel unit. By precisely adjusting the luminous intensity and mixing ratio of the three primary colors, high-quality full-color effects can be achieved. Compared to traditional light sources, Micro LED has significant advantages: brightness can reach over 10,000 nits, response time is as fast as microseconds, and lifespan exceeds 100,000 hours. It boasts numerous advantages such as ultra-high brightness, miniaturized design, independent control, fast response, and ultra-long lifespan.

[0029] Using Micro LEDs as the innovative illumination source for a spectral confocal system offers significant advantages: high light source uniformity, uniform spectral energy, high measurement resolution, and fast measurement speed. Specifically, by precisely adjusting the driving voltage of the RGB three-color Micro LEDs, the light energy of each wavelength is uniformly distributed, generating equal-energy white light with a constant spectral energy density. Employing a line-by-line scanning method to illuminate the white light source composed of the three RGB rows enables rapid scanning of the entire detection area, achieving a spatial resolution down to the micrometer level.

[0030] Step 102: The beam splitter transmits part of the collimated light to the dispersive objective lens, which converges light of different wavelengths at different positions on the optical axis of the dispersive objective lens. The converged light shines on the surface of the object being measured and is reflected.

[0031] The beam-splitter utilizes the difference in reflectivity at the interface of the medium to split light. The splitting ratio can be set as needed. For example, in this invention, the beam-splitter can be set to 50% transmission / 50% reflection. In step 102, the transmitted light enters the dispersive objective lens, and the reflected light is absorbed and does not participate in subsequent processes.

[0032] Understandably, dispersive objectives utilize the dispersive properties of optical materials to focus light of different wavelengths at different positions on the optical axis. For example, light with wavelength λ1 is focused at depth Z1, and light with wavelength λ2 is focused at depth Z2.

[0033] When a certain wavelength of light from a dispersive objective lens is focused precisely on the surface of the object being measured, that wavelength of light will be reflected back into the system, while other defocused wavelengths of light will be suppressed due to scattering or failure to meet the confocal condition.

[0034] Step 103: The light beam reflected from the object under test returns to the beam splitter after passing through the dispersive objective lens. Part of the light is reflected by the beam splitter to the first focusing lens, and after focusing, it is projected onto one of the array slits. This slit is conjugate to the position of the surface light source and the position of the object under test. Step 104: After the light beam passing through the slit is beam split and imaged, a two-dimensional spectral image is obtained; the two-dimensional spectral image includes spatial location information and corresponding wavelength information.

[0035] Optionally, in the X-axis direction of the two-dimensional spectral image, different positions on the scanning line of the corresponding object surface can be determined based on spatial location information; in the Y-axis direction of the two-dimensional spectral image, the intensity distribution of light at different wavelengths can be determined based on wavelength information.

[0036] Step 105: Based on the spatial location information and wavelength information of the two-dimensional spectral image, obtain the height information of each point on the scanning line of the surface of the object being measured.

[0037] This invention can pre-calibrate the mapping relationship between wavelength and the height of the surface of the object being measured, thereby facilitating the calculation of height information based on wavelength according to the mapping relationship.

[0038] Optionally, step 105 includes: determining the height information of points on the scan line based on the peak wavelength corresponding to the spatial location information of the two-dimensional spectral image; wherein the spatial location information of the two-dimensional spectral image and the points on the scan line have a one-to-one mapping relationship.

[0039] Specifically, based on the wavelength information corresponding to each spatial location, the peak wavelength (i.e., the wavelength with the strongest reflected light) is identified. Using a known wavelength-height calibration curve, this peak wavelength is converted into a corresponding height value. The height information of all spatial points is combined to form the height profile of that scan line.

[0040] Step 106: By switching the light emission rows of the surface light source line by line, repeat steps 101 to 105 to complete the scanning of the entire surface of the object under test and obtain the three-dimensional shape of the entire surface of the object under test.

[0041] Light up each row of the surface light source in sequence, repeat steps 101-105, obtain the spatial-wavelength data of each row to determine the height profile, stitch together the height profiles of each row, and finally obtain a complete three-dimensional topographic map of the surface of the object being measured.

[0042] Based on the above embodiments, as an optional embodiment, in step 104, the light beam passing through the slit is imaged by beam splitting to obtain a two-dimensional spectral image, which includes: the light beam passing through the slit is collimated by a second collimating lens; the light collimated by the second collimating lens is split by a diffraction grating and then passes through a second focusing lens to obtain a two-dimensional spectral image by a detector.

[0043] Understandably, the focal length and position design of the second collimating lens make the light beam become parallel after passing through the lens, eliminating the divergence of the light beam; it provides uniform incident light for subsequent beam splitting operations (diffraction grating), ensuring that light of different wavelengths can be effectively separated.

[0044] The second focusing lens focuses the split parallel beam onto the detector to form a two-dimensional spectral image.

[0045] On the other hand, the present invention also provides a spectral confocal three-dimensional topography measurement system based on a surface light source. Figure 2 This is a schematic diagram of the structure of the spectral confocal three-dimensional topography measurement system based on a surface light source provided by the present invention, as shown below. Figure 2 As shown, the system includes: A surface light source is used to emit uniform white light with constant spectral energy density line by line; wherein, the surface light source can be a MicroLED surface light source, which includes an independently driveable RGB three-color pixel array.

[0046] The first collimating lens (i.e.) Figure 2 The collimating lens (located in the light-emitting path of the surface light source) is used to collimate the emitted light rays. The beam-splitting prism receives light rays that have been collimated by the first collimating lens and transmits a portion of the light rays to the dispersive objective lens. A dispersive objective lens is disposed on the transmission optical path of the beam splitter to focus light of different wavelengths at different positions on its optical axis, thereby forming a converging illumination on the surface of the object under test and receiving the reflected light from the surface of the object under test. First focusing lens (i.e.) Figure 2 The focusing lens (located in the beam splitter's reflected light path) is used to focus the light rays returning from the dispersive objective and reflected by the beam splitter. An array of slits, disposed on the focal plane of the first focusing lens, is used to receive the focused light beam and pass it through one of the slits; Spectrophotometer module (i.e.) Figure 2 The spectrometer in the image is used to split and image a beam of light passing through a slit, and to acquire a two-dimensional spectral image containing spatial location information and wavelength information; the two-dimensional spectral image includes spatial location information and corresponding wavelength information. Processing module (not in) Figure 2As shown in the image, it can communicate with the spectroscopic imaging module via wired or wireless means. It is used to calculate the height information of each point on the scanning line of the surface of the object under test based on the peak wavelength corresponding to the spatial position information in the two-dimensional spectral image, and to complete the reconstruction of the three-dimensional morphology of the entire surface by switching the light emission rows of the surface light source line by line.

[0047] The specific implementation schemes involved in the processing module can be found in steps 105 and 106 of the above embodiments, and will not be repeated here.

[0048] Figure 3 This is a schematic diagram of spectral imaging using a spectral imaging module provided by the present invention, as shown below. Figure 3 As shown, the spectroscopic imaging module includes: The second collimating lens (i.e.) Figure 3 The collimating lens in the slit is used to collimate the light beam passing through it. A diffraction grating, located in the output light path of the second collimating lens, is used to split the collimated beam. The second focusing lens (i.e.) Figure 3 The focusing lens (in the diffraction grating) is located in the output light path of the diffraction grating and is used to focus the split beam onto the detector; A detector is used to receive a focused beam of light and form a two-dimensional spectral image.

[0049] Based on the above-described surface light source-based spectral confocal three-dimensional topography measurement system, the following describes the implementation of the surface light source-based spectral confocal three-dimensional topography measurement method of the present invention applied to the system.

[0050] Step 1: Prepare a high-brightness full-color surface light source such as Micro LED, a collimating lens, a beam splitter prism, a dispersive objective lens, the object to be measured, a focusing lens, an array slit, a diffraction grating, a detector, etc., to arrange the system of the present invention according to the above embodiments; Step 2: Light up one row of the Micro LED surface light source to emit high-brightness white light of equal energy, which passes through the first collimating lens and the beam splitter and enters the dispersive objective lens; Step 3: Due to the axial dispersion of the dispersive objective, light with wavelengths of λ1, λ2, ..., λn converges sequentially at different positions along the optical axis of the dispersive objective. After being reflected by the object under test, the converged light is focused by the dispersive objective and the first focusing lens onto one of the array slits. Step 4: After the light passing through the slit is collimated and diffracted by the grating, the detector obtains a two-dimensional spectral image. One direction is the spatial position information, and the other direction is the wavelength information. After data processing, the peak wavelength corresponding to each point on a line of the measured object can be obtained, and then decoded into the depth of each point on the line.

[0051] Step 5: Determine whether the scanning of the entire surface of the object under test has been completed. If yes, end the process; otherwise, return to step 2 and light up different rows of Micro LEDs in sequence to achieve scanning of the entire surface of the object under test. Step 6: Calculate the height of the object's surface at the peak wavelength on the spectrometer detector, thereby achieving a three-dimensional shape measurement of the entire object.

[0052] Step 2 includes: Step 201: By precisely adjusting the RGB three-color driving voltage of the Micro LED, the light energy of each wavelength is evenly distributed to generate equal-energy white light with constant spectral energy density; Step 202: Light up one row of white light from the Micro LED sequentially, consisting of three rows of RGB, and scan the entire area. Step 203: The light rays pass through the collimating lens to the beam splitter. Half of the light rays pass through the beam splitter and enter the dispersive prism, while the other half of the light rays are reflected by the beam splitter and become internal stray light, which is absorbed by the inner wall of the machine.

[0053] Step 3 includes: Step 301: The dispersive objective lens disperses the collimated white light into beams of different wavelengths; Step 302: Beams of different wavelengths converge sequentially along the optical axis at the dispersive objective lens; Step 303: The converging beam shines on the surface of the object being measured and is reflected; Step 304: The reflected light passes through the dispersive objective lens and reaches the beam splitter. Half of the light passes through the beam splitter, and the other half is reflected by the beam splitter into the first focusing prism. The reflected light converges on one of the array slits.

[0054] Step 4 includes: Step 401: The light passing through the slit is collimated by the second collimating lens and dispersed by the diffraction grating. It is then focused by the second focusing lens and detected by the detector to obtain a two-dimensional spectral image. One direction contains spatial position information, and the other direction contains wavelength information. After data processing, the peak wavelength corresponding to each point on a line of the measured object can be obtained, and then decoded into the depth (height information) of each point on the line.

[0055] Step 6 includes: Step 601: Calculate the peak wavelength corresponding to each point on a line of the object under test from the image detected by the spectrometer; Step 602: Obtain the height information of a line on the object being measured by the one-to-one correspondence between wavelength and height of the object being measured.

[0056] Step 603: Obtain the three-dimensional shape data of the entire object by acquiring the height information of each line of the object being measured.

[0057] Furthermore, in one specific embodiment, the wavelength of the high-brightness full-color surface light source such as Micro LED is 400-700nm. The size of a single row of Micro LEDs is 10um×10mm. When a single row is lit (corresponding to three RGB rows), the light spot size on the surface of the object being measured after passing through a 1.3x dispersive objective lens is 13um×13mm. The light reflected by the object is focused onto the slit array. The light spot size at the slit position is 10um and 10mm. After the light passes through the slits, it is split by the diffraction grating and focused by the focusing lens. Light of different wavelengths is focused onto different rows of the detector, and the peak wavelength detected is decoded into height information.

[0058] The axial chromatic aberration characteristics of the dispersive objective lens enable this function of different wavelengths to be focused at different heights on the surface of the object being measured. The maximum axial measurement height can reach 6mm, and the maximum measurement area in the XY direction is 13mm×13mm.

[0059] When the middle row of Micro LEDs is lit, an equal-energy white light source passes through the array slits, and a spectrometer detects a two-dimensional spectral image. Figure 4 To reduce the size of the light source and slit and improve the speed of light tracing, the spectrometer detects a two-dimensional spectral image, with the horizontal axis representing spatial location information and the vertical axis representing wavelength information.

[0060] Based on two-dimensional spectral images, the height information of any point on the scan line of the object being measured can be determined.

[0061] In summary, the spectral confocal three-dimensional topography measurement method and system based on a surface light source provided by this invention has the advantages of high light source brightness, high light source uniformity, uniform energy distribution across wavelengths, fast scanning speed, and high spatial resolution. Compared with linear illumination plus mechanical scanning, it eliminates the instability of mechanical motion and achieves higher resolution; compared with DMD for achieving lateral movement of the illumination beam, it has higher light source brightness, a simpler system, and higher light energy utilization. Specific beneficial effects are analyzed as follows: (1) Fast measurement speed. By lighting one row of the surface light source (which can be a Micro LED surface light source), information on one line can be obtained in a single operation. By switching different rows of the surface light source, the three-dimensional shape information of the object under test can be quickly obtained, which solves the problem of slow imaging speed of the confocal system based on linear illumination and mechanical scanning.

[0062] (2) High system stability. Compared with the movement of objects on a displacement stage, the stability of controlling the movement of the beam by lighting up the Micro LED surface light source in different rows is better, which can meet the needs of modern industrial production and scientific research for rapid and stable measurement.

[0063] (3) High measurement accuracy. Based on the different rows of the Micro LED surface light source to realize beam movement, continuous line illumination of the surface of the object being measured can be achieved, and the spatial resolution can reach the micrometer level, which solves the problem that the sensitivity and resolution of the existing technology need to be improved.

[0064] (4) Simple structure and low cost. Line illumination at different positions is achieved based on Micro LED surface light source, which is simpler and lower in cost than the complex DMD micro-mirror array structure, and solves the problems of complex system integration and high cost of surface spectral confocal system based on digital micromirror device.

[0065] (5) High light energy utilization. As a surface light source, Micro LED can participate in imaging with light emitted from each row, and there is no stray light problem. It has high light energy utilization, which solves the problem of low light energy utilization in surface spectral confocal systems based on digital micromirror devices.

[0066] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring three-dimensional topography based on spectral confocal imaging using a surface light source, characterized in that, include: Step 101: Equal-energy white light with constant spectral energy density is emitted line by line through a surface light source, and then enters the beam splitter after being collimated by the first collimating lens; Step 102: The beam splitter transmits part of the collimated light to the dispersive objective lens, which converges light of different wavelengths at different positions on the optical axis of the dispersive objective lens. The converged light shines on the surface of the object being measured and is reflected. Step 103: The light beam reflected by the object under test returns to the beam splitter after passing through the dispersive objective lens. Part of the light beam is reflected by the beam splitter to the first focusing lens, and after being focused, it is projected onto one of the slits of the array slits. Step 104: After the light beam passing through the slit is split and imaged, a two-dimensional spectral image is obtained; the two-dimensional spectral image includes spatial location information and corresponding wavelength information; wherein, the spatial location information of the two-dimensional spectral image has a one-to-one mapping relationship with the points on the scan line; Step 105: Based on the spatial position information and wavelength information of the two-dimensional spectral image, obtain the height information of each point on the scanning line of the surface of the object under test; Step 106: By switching the light emission rows of the surface light source line by line, repeat steps 101 to 105 to complete the scanning of the entire surface of the object under test and obtain the three-dimensional shape of the entire surface of the object under test.

2. The method for measuring three-dimensional topography based on a surface light source using spectral confocal imaging according to claim 1, characterized in that, The surface light source is a Micro LED surface light source, which includes an independently driveable RGB three-color pixel array.

3. The method for measuring three-dimensional topography based on a surface light source using spectral confocal imaging according to claim 2, characterized in that, Step 101 includes: By adjusting the RGB three-color driving voltage of the Micro LED surface light source, the energy of each wavelength of light is evenly distributed to generate equal-energy white light.

4. The spectral confocal three-dimensional topography measurement method based on a surface light source according to claim 2, characterized in that, In step 104, the light beam passing through the slit is subjected to spectral imaging to obtain a two-dimensional spectral image, including: The light beam passing through the slit is collimated by the second collimating lens; The light collimated by the second collimating lens is dispersed by the diffraction grating and then passes through the second focusing lens to obtain a two-dimensional spectral image by the detector.

5. The spectral confocal three-dimensional topography measurement method based on a surface light source according to claim 2, characterized in that, Step 105 includes: Based on the peak wavelength corresponding to the spatial location information of the two-dimensional spectral image, the height information of the points on the scan line is determined; In this system, the spatial location information of the two-dimensional spectral image has a one-to-one mapping relationship with the points on the scan line.

6. The method for measuring three-dimensional topography based on a surface light source using spectral confocal imaging according to claim 1, characterized in that, The ratio of transmitted to reflected light by the beam splitter is 1:

1.

7. The method for measuring three-dimensional topography based on a surface light source using spectral confocal imaging according to claim 5, characterized in that, Before determining the height information of points on the scan line based on the peak wavelength corresponding to the spatial location information of the two-dimensional spectral image, the process also includes: The mapping relationship between the calibrated wavelength and the height of the surface of the object being measured is established so that the height information of the surface of the object being measured can be determined based on the peak wavelength.

8. A spectral confocal three-dimensional topography measurement system based on a surface light source, characterized in that, include: A surface light source used to emit equal-energy white light with a constant spectral energy density line by line; The first collimating lens is located on the light-emitting path of the surface light source and is used to collimate the emitted light rays; The beam-splitting prism receives light rays that have been collimated by the first collimating lens and transmits a portion of the light rays to the dispersive objective lens. A dispersive objective lens is disposed on the transmission optical path of the beam splitter to focus light of different wavelengths at different positions on its optical axis, thereby forming a converging illumination on the surface of the object under test and receiving the reflected light from the surface of the object under test. The first focusing lens is located in the reflected light path of the beam splitter and is used to focus the light rays that return from the dispersive objective and are reflected by the beam splitter. An array of slits, disposed on the focal plane of the first focusing lens, is used to receive the focused light beam and pass it through one of the slits; The beam splitting and imaging module is used to split and image the light beam passing through the slit to obtain a two-dimensional spectral image containing spatial location information and wavelength information; the two-dimensional spectral image includes spatial location information and corresponding wavelength information. The processing module is used to calculate the height information of each point on the scanning line of the surface of the object under test based on the peak wavelength corresponding to the spatial position information in the two-dimensional spectral image, and to complete the reconstruction of the three-dimensional morphology of the entire surface by switching the light emission rows of the surface light source line by line.

9. The spectral confocal three-dimensional topography measurement system based on a surface light source according to claim 8, characterized in that, The surface light source is a Micro LED surface light source, which includes an independently driveable RGB three-color pixel array.

10. The spectral confocal three-dimensional topography measurement system based on a surface light source according to claim 8, characterized in that, The spectroscopic imaging module includes: The second collimating lens is used to collimate the light beam passing through the slit; A diffraction grating, located in the output light path of the second collimating lens, is used to split the collimated beam. The second focusing lens, located in the outgoing light path of the diffraction grating, is used to focus the split beam onto the detector. A detector is used to receive a focused beam of light and form a two-dimensional spectral image.

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