Triangular optical measurement system

Abstract

The application relates to a triangular optical measurement system, an illumination module comprising a first functional light splitting element and at least two light sources, the first functional light splitting element being an element for reflecting and transmitting at least two lights with different characteristics in the same direction without interference to generate two non-coherent line lights for detecting a measured object at the same time. The illumination module further comprises a slit element arranged between the first functional light splitting element and the light sources. The illumination light emitted by each light source is output to the first functional light splitting element in the form of line light after passing through the corresponding slit element. The slit of the slit element is adjustable in the width direction position. The slit element can be adjusted according to actual needs to make the optical paths of the non-coherent line lights different or coincide, capture image information of non-coherent line lights with different characteristics on the surface of the measured object, obtain more fine and accurate images, and improve the detection precision or detection efficiency.

Description

[0001] This application is a divisional application filed with the Chinese Patent Office on December 31, 2024, with application number 202412000451.1 and entitled "Triangulation Optical Measurement System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical inspection technology, and in particular to a triangulation optical measurement system. Background Technology

[0003] A 3D line scan optical inspection system is an optical system used for high-precision three-dimensional measurement and inspection. A laser or high-power LED line light source and an industrial camera are positioned at a fixed angle relative to each other, performing a line scan on the object's surface. The industrial camera captures the changes in the position of the reflection points on the object's surface, and the three-dimensional coordinates of each point on the surface of the measured object are calculated in real time using triangulation. Compared to traditional contact measurement methods, 3D line scan optical inspection systems have the advantages of being non-contact and non-destructive, making them suitable for measuring objects with complex shapes or sensitive surfaces. They can quickly and efficiently generate three-dimensional morphological information of the object's surface and are widely used in industrial inspections such as semiconductor wafer inspection, photoresist thickness measurement, and microstructure morphology measurement of semiconductor components. However, traditional optical inspection systems use a single light source for illumination, resulting in insufficient information acquisition and disadvantages such as low detection accuracy or low detection efficiency. Summary of the Invention

[0004] Therefore, it is necessary to provide a triangulation optical measurement system that can improve detection accuracy or detection efficiency to address the above problems.

[0005] A triangulation optical measurement system, comprising:

[0006] An illumination module includes a first functional beam splitter and at least two light sources. The first functional beam splitter splits the illumination light emitted by the at least two light sources into at least two incoherent line beams with different characteristics, which are incident on the surface of the object under test in the same direction. The first functional beam splitter is an element that reflects and transmits at least two beams of light with different characteristics and then emits them in the same direction without interference, so as to generate two incoherent line beams to detect the object under test simultaneously. The illumination module also includes a slit element disposed between the first functional beam splitter and the light sources. The illumination light emitted by each light source passes through the corresponding slit element and forms a line beam, which is then output to the first functional beam splitter. The position of the slit of the slit element is adjustable along the width direction so that the optical paths of the incoherent line beams are different or coincident.

[0007] Imaging module.

[0008] In one embodiment, the illumination module further includes a first lens and a first microscope objective. The first functional beam splitter, the first lens, and the first microscope objective are arranged sequentially along the optical path. The incoherent line light output by the first functional beam splitter passes through the first lens and the first microscope objective and is incident on the surface of the object to be tested.

[0009] In one embodiment, the first functional beam splitter splits the illumination light into incoherent line light of different wavelengths or different polarization states.

[0010] In one embodiment, the imaging module includes at least one image acquisition unit for simultaneously acquiring reflected images of at least two of the incoherent line lights as a periodic region of interest image.

[0011] The triangulation optical measurement system also includes a control module, which is used to periodically acquire images of the region of interest on the object under test when the object under test is displaced along a preset scanning path.

[0012] In one embodiment, the control module controls the imaging module to perform image acquisition by exposure according to a set period. The control module also controls the displacement of the object under test along a preset scanning path within the set period, which is consistent with the width of the region of interest of the object under test incident on the incoherent line light in the preset scanning path direction, so that the region of interest corresponding to each image acquisition is continuous and non-overlapping in the preset scanning path direction.

[0013] In one embodiment, the control module controls the imaging module to perform image acquisition by exposure according to a set period. The control module also controls the displacement of the object under test along a preset scanning path within the set period to be less than the width of the region of interest of the object under test incident on the incoherent line light in the direction of the preset scanning path, so that the region of interest corresponding to each image acquisition is continuous and at least partially overlapped in the direction of the preset scanning path.

[0014] In one embodiment, at least two of the incoherent line lights include a first line light and a second line light arranged in parallel; the scanning area of ​​the first line light in the current region of interest overlaps with the scanning area of ​​the second line light in the previous consecutive region of interest.

[0015] In one embodiment, the number of image acquisition units is two or more, and the imaging module further includes a second functional beam splitter. The second functional beam splitter transmits or reflects the line light reflected by the object under test, separates incoherent line light with different characteristics, and transmits it to the corresponding image acquisition unit.

[0016] In one embodiment, the imaging module further includes a second lens and a second microscope objective. The second microscope objective, the second lens, and the second functional beam splitter are arranged sequentially along the optical path. The line light reflected by the object under test is transmitted through the second microscope objective and the second lens to the second functional beam splitter for transmission or reflection, separating incoherent line light with different characteristics and transmitting it to the corresponding image acquisition device.

[0017] In one embodiment, the first functional beam splitter is a dichroic mirror or a polarizing beam splitter, and the second functional beam splitter is a dichroic mirror or a polarizing beam splitter.

[0018] In one embodiment, the illumination module further includes an image acquisition unit, and the imaging module further includes a light source; in the imaging module, the second functional beam splitter separates the illumination light emitted by the corresponding light source into line light with different characteristics and transmits them to the object under test; in the illumination module, the first functional beam splitter separates the line light reflected by the object under test and obtains line light with different characteristics, which is then transmitted to the corresponding image acquisition unit.

[0019] The aforementioned triangulation optical measurement system includes an illumination module comprising a first functional beam splitter and at least two light sources. The first functional beam splitter is an element that reflects and transmits at least two beams of light with different characteristics, emitting them in the same direction without interference, thereby generating two incoherent line beams for simultaneous detection of the object under test. The illumination module also includes a slit element disposed between the first functional beam splitter and the light sources. The illumination light emitted by each light source passes through the corresponding slit element and forms line beams, which are then output to the first functional beam splitter. The position of the slit element along its width is adjustable, allowing the slit element to be adjusted according to actual needs to make the optical paths of the incoherent line beams different or coincident, capturing image information of incoherent line beams with different characteristics on the surface of the object under test, obtaining more refined and accurate images, and improving detection accuracy or efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a triangulation optical measurement system in one embodiment;

[0021] Figure 2 This is a schematic diagram of the structural principle of a triangulation optical measurement system in one embodiment;

[0022] Figure 3 This is a schematic diagram of the triangulation optical measurement system in another embodiment;

[0023] Figure 4 This is a schematic diagram of a line scan of the surface of the object under test in one embodiment;

[0024] Figure 5 This is a schematic diagram of the illumination and imaging timing in one embodiment;

[0025] Figure 6 This is a schematic diagram of the lighting and imaging timing in another embodiment;

[0026] Figure 7 This is a schematic diagram of image acquisition of the region of interest of the object under test in some embodiments;

[0027] Figure 8 This is a schematic diagram of the illumination and imaging timing for single-source illumination detection.

[0028] Figure 9 This is a schematic diagram of image acquisition of the region of interest of the test object in the existing single-source illumination detection technology. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0032] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, method, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, methods, operations, components, parts, or combinations thereof.

[0033] In one embodiment, such as Figure 1 and Figure 2As shown, a triangulation optical measurement system is provided, including an illumination module 100, an imaging module 200, and a control module (not shown). The illumination module 100 includes a first functional beam splitter 110 and at least two light sources. The first functional beam splitter 110 is used to split the illumination light emitted by the at least two light sources into at least two incoherent line beams with different characteristics, which are incident on the surface of the object under test in the same direction (meaning the transmission directions are approximately the same, not necessarily perfectly parallel). The imaging module 200 includes at least one image acquisition unit, used to simultaneously acquire the reflected images of at least two incoherent line beams as a periodic region of interest image. The control module is used to periodically acquire the region of interest image on the object under test when the object under test is displaced along a preset scanning path.

[0034] The object to be tested can be a wafer or other product requiring surface image inspection. The number of light sources can be two or more, such as light source A, light source B, etc. The light sources can be constant-on light sources, continuously providing illumination, or they can be strobe light sources, flashing once per cycle to provide illumination. The type of illumination light emitted by the light sources is not unique; for example, the light source can be a laser source with different wavelengths or polarization states, or a broadband light source with different wavelengths or polarization states, etc.

[0035] Correspondingly, the first functional beam splitter 110 splits the illumination light from each light source into incoherent line light with different characteristics, which can be to split the illumination light into incoherent line light with different wavelengths or different polarization states. (Refer to...) Figure 2 In this embodiment, the first functional beam splitter 110 can specifically be a dichroic mirror or a polarizing beam splitter. The polarizing beam splitter can specifically be a polarizing beam splitter prism or a polarizing beam splitter plate. The dichroic mirror can specifically be a short-pass dichroic mirror, a long-pass dichroic mirror, a multi-band dichroic mirror, etc. The short-pass dichroic mirror has high transmittance for light below the cutoff wavelength and high reflectivity for light above the cutoff wavelength; the long-pass dichroic mirror has high transmittance for light above the starting wavelength and high reflectivity for light below the starting wavelength; the multi-band dichroic mirror has three or more transmission or reflection bands, for example, high transmittance for bands between the cutoff wavelength and the starting wavelength and high reflectivity for other bands.

[0036] The above specific examples are only illustrative of the first functional beam splitter 110. In other embodiments, it is sufficient to reflect and transmit two beams of different wavelengths (or polarization states) from the reflective and transmissive surfaces of the functional beam splitter and then emit them out in the same direction to the object under test.

[0037] It should be emphasized that the first functional beam splitter 110 in this application is different from ordinary beam splitters or beam splitters. Ordinary beam splitters or beam splitters only have a single beam splitting function and do not have the characteristic of selective reflection or transmission of light of different wavelengths or polarization states. However, the first functional beam splitter 110 in this application can reflect and transmit at least two beams of light with different characteristics and emit them in the same direction without interference (or with low coherence), so as to generate two incoherent line beams to detect the object under test at the same time and improve the detection efficiency.

[0038] The number of image acquisition devices can be one or more, such as industrial camera 1, industrial camera 2, etc. The type of image acquisition device is also not unique; it can be a line scan camera, area scan camera, etc. When there is only one image acquisition device, it acquires the reflected images of at least two incoherent line lights with different characteristics. When there are multiple image acquisition devices, each image acquisition device can acquire the reflected images of one or more line lights with different characteristics. In this embodiment, using multiple image acquisition devices to acquire line lights of different wavelengths / polarization states respectively enables better imaging.

[0039] The control module connects to the imaging module and the platform on which the test object is placed. It controls the platform to move the test object along a preset scanning path, generating displacement (i.e., preset step displacement), and controls the imaging module to perform exposure and image acquisition, obtaining an image of the region of interest on the test object. The region of interest image refers to the image obtained by acquiring images of the region of interest on the test object in each cycle. The specific region of interest can be determined based on the field of view (FOV) of the image acquisition device. For example, when the image acquisition device uses a line scan camera, its FOV is 1*n or 2*n pixels. Therefore, the region of interest can be set to m or m / 2 FOVs. In each cycle, the light source flashes once or remains constantly lit, and the line scan camera performs multiple exposures, acquiring images of all m*n pixels of the region of interest in that cycle, thus obtaining the region of interest image. When an image acquisition device uses an area scan camera, its field of view (FOV) is relatively large (which can be understood as similar to a square). In general triangulation, each frame of the image is a bar-shaped region of interest corresponding to the shape of the line light. To ensure the continuity of the bar-shaped region of interest, the preset step displacement is generally smaller than the FOV width in the displacement direction. This means that two consecutive FOVs may overlap. Therefore, a bar-shaped region of interest (ROI) containing the line light can be selected within the FOV as the region of interest, and scanning is performed sequentially according to the ROI region—this is the ROI scanning mode. These regions of interest may or may not overlap. In other words, if the image acquisition device is a regular line scan camera, the region of interest is the area stitched together from multiple exposures within a cycle; if it is a TDI camera, the region of interest can also be the FOV or ROI region of the TDI camera.

[0040] Within each cycle, each light source flashes once, and the control module controls each image acquisition unit to perform one or more exposures, acquiring the reflected image of incoherent line light from the surface of the object under test to obtain the region of interest image for that cycle, capturing the surface feature information of the object in real time. By combining the region of interest images acquired in different cycles, the different heights of the surface of the object under test can be analyzed. By using multiple light sources to provide illumination, and utilizing the first functional beam splitter 110 to split the illumination light emitted by each light source into incoherent line light with different characteristics, image information of incoherent line light with different characteristics can be captured from the surface of the object under test, obtaining more refined and accurate images.

[0041] Furthermore, the control module is also used to determine the three-dimensional height information of the object under test within the current region of interest based on the reflected image information of line light in the region of interest image. Further, by sequentially stitching adjacent regions of interest together, a complete image of the object under test can be formed. Figure 4 (This is used to analyze the three-dimensional height information or two-dimensional size information of the surface of the object under test, etc.)

[0042] In one embodiment, such as Figure 2 As shown, the illumination module 100 also includes a first lens 120 and a first microscope objective 130. The first functional beam splitter 110, the first lens 120 and the first microscope objective 130 are arranged sequentially along the optical path. The incoherent line light output by the first functional beam splitter 110 passes through the first lens 120 and the first microscope objective 130 and is incident on the surface of the object to be tested.

[0043] like Figure 1 and Figure 2 As shown, the lighting module 100 also includes a first housing 101, a first functional beam splitter 110 and a first lens 120 disposed within the first housing 101, and the first housing 101 is provided with fiber optic mounting interfaces, such as fiber optic mounting interface a and fiber optic mounting interface b, which are respectively connected to the corresponding light source via optical fibers. Further, the lighting module 100 may also include a first objective lens converter 140, which is disposed on the first housing 101. There are multiple first microscope objectives 130, each with a different magnification. Each first microscope objective 130 is disposed on the first objective lens converter 140, which can drive each first microscope objective 130 to rotate relative to the first housing 101. In the illumination module 100, the first lens 120 and the first microscope objective 130 are combined to form an infinity correction optical system. Different magnifications of the first microscope objective 130 can be reasonably selected and combined according to actual needs to optimize the illumination. By changing the linewidth of the illumination source through the first microscope objective 130, the magnification function of imaging illumination can be realized.

[0044] like Figure 2 and Figure 3As shown, the lighting module 100 may further include a slit element 150 disposed between the first functional beam splitter 110 and the light source. Illumination light emitted by each light source passes through the corresponding slit element 150 and is then output as line light to the first functional beam splitter 110. Specifically, the slit element 150 may be a grating sheet. The slit element 150 can be positioned between the fiber optic mounting interface and the first functional beam splitter 110. The light source transmits illumination light to the fiber optic mounting interface via optical fiber. After passing through the slit elements 150 at different slit positions, the light spot forms a narrow, elongated line shape, creating two rows of line light. These two rows of line light pass through the functionally selective first functional beam splitter 110, separating them into two lines of line light with different spectra or different polarization states.

[0045] The slits of the slit element 150 are adjustable along their width direction, allowing the optical paths of incoherent line beams to differ or coincide. By adjusting the positions of the two slits on the slit element 150 along their width direction, the relative positions of the emitted line beams on the object side of the illumination module 100 can be changed, thereby altering the width-direction spacing of the line beams on the image side of the illumination module 100 (i.e., the line beams striking the object under test) to a suitable range. The distance between the two slits on the slit element 150 can be adjusted according to actual conditions to change the optical paths of the two lines of line beams generated, meeting different testing needs.

[0046] In one embodiment, such as Figure 2 As shown, the number of image acquisition units is two or more. The imaging module 200 also includes a second functional beam splitter 210. The second functional beam splitter 210 transmits or reflects the line light reflected by the object under test, separating incoherent line light with different characteristics and transmitting it to the corresponding image acquisition unit. The second functional beam splitter 210 can also be a dichroic mirror, a polarizing beam splitter, or other beam splitting elements. The function of the second functional beam splitter 210 is basically the same as that of the first functional beam splitter 110. The difference is that the second functional beam splitter 210 splits two incoherent line light beams with different characteristics from the same direction and transmits them to the corresponding image acquisition unit. Different materials have different spectral responses at different wavelengths and have different polarization reflection characteristics. To address the different material characteristics of the surface of the object under test, the illumination module 100 and the imaging module 200 employ a first functional beam splitter 110 and a second functional beam splitter 210 with functional selectivity to selectively separate the illumination light and imaging light into light with different spectra or different polarization states. This makes the light spot illuminating the surface of the object under test appear as a line or strip, so as to obtain the depth information of the surface features of the object under test more quickly and accurately. This enables multispectral detection or polarization imaging detection, thereby obtaining richer and clearer feature images and more accurately extracting detailed information from complex backgrounds.

[0047] Furthermore, the imaging module 200 also includes a second lens 220 and a second microscope objective 230. The second microscope objective 230, the second lens 220, and the second functional beam splitter 210 are arranged sequentially along the optical path. The line light reflected from the object under test is transmitted through the second microscope objective 230 and the second lens 220 to the second functional beam splitter 210 for transmission or reflection, separating incoherent line light with different characteristics and transmitting it to the corresponding image acquisition device. The second microscope objective 230 and the second lens 220 are combined to form an infinity-corrected optical system. By changing the number of pixels corresponding to the line light image in the industrial camera through the second microscope objective 230, the imaging is optimized, a more refined and accurate image is obtained, and the detection accuracy of the entire system is improved.

[0048] In addition, the imaging module 200 also includes a second housing 201, a second lens 220 and a second functional beam splitter 210 disposed within the second housing 201, and an image acquisition unit disposed on the second housing 201. Figure 1 As shown, the imaging module 200 may further include a second objective lens converter 240, which is mounted on the second housing 201. Multiple second microscope objectives 230 are included, each with a different magnification. Each second microscope objective 230 is mounted on the second objective lens converter 240, which can rotate each second microscope objective 230 relative to the second housing 201. Different magnification second microscope objectives 230 can be rationally selected and combined according to actual needs to optimize imaging, thereby ensuring optimal imaging accuracy and resolution.

[0049] By setting multiple microscope objectives with different magnifications in the illumination module 100 and the imaging module 200 respectively, and using corresponding objective converters, different magnifications of illumination and imaging can be achieved. For different sizes and structural features of the surface of the object under test, microscope objectives with different magnifications can be rationally selected and combined to optimize imaging and illumination, thereby ensuring optimal imaging accuracy and resolution.

[0050] In one embodiment, taking a dichroic mirror as an example, where the first functional beam splitter 110 and the second functional beam splitter 210 are both dichroic elements, the light source can be a laser source of different wavelengths or a broadband light source. For example... Figures 1 to 3As shown, in the illumination module 100, illumination fibers are installed in fiber optic mounting interfaces a and b, respectively. Slit elements 150 are added between fiber optic mounting interfaces a and b and the first functional beam splitter 110. The slit positions of the two slit elements 150 are different, and the slit widths can be the same or different, depending on the characteristic dimensions of the surface of the object under test. Illumination light emitted by light sources A and B is guided into the first housing 101 through the illumination fibers. During this process, the light passes through the slit elements 150 at different slit positions, forming two rows of linear light. The two rows of linear light are separated into two rows of linear light with different spectra by a dichroic mirror. These two rows of linear light are then magnified by a combination of the first lens 120 and the first microscope objective 130 and illuminate the same area of ​​interest on the surface of the object under test, forming two different fields of view for detection. Figure 4 The two lines of illumination beams, WL1 and WL2, are shown. After being reflected by the surface of the object under test, they enter the second microscope objective 230 and the second lens 220 in the imaging module 200 for further magnification. Then, they are selectively separated by a dichroic mirror, so that line beam WL1 is imaged in industrial camera 1 and line beam WL2 is imaged in industrial camera 2, realizing simultaneous imaging and detection of dual fields of view.

[0051] In another embodiment, taking the first functional beam splitter 110 and the second functional beam splitter 210 as examples, which employ polarizing beam splitters, the light source can be a laser source with different polarization states or a broadband light source. If the object under test is a polarization-maintaining material, using polarization imaging detection can enhance image contrast and color saturation, more effectively highlighting specific structures or features, and improving imaging quality. Similarly, referring to... Figures 1 to 3 In the illumination module 100, illumination optical fibers are installed in optical fiber mounting interfaces a and b, respectively. Slit elements 150 are added between optical fiber mounting interfaces a and b and the first functional beam splitter 110. The slit positions of the two slit elements 150 are different, and their slit widths can be the same or different, depending on the characteristic dimensions of the surface of the object under test. Illumination light emitted by light sources A and B is guided into the first housing 101 through the illumination optical fibers. During this process, the light passes through the slit elements 150 at different slit positions, forming two rows of linear light. These two rows of linear light are separated into two rows of linear light with different polarization states—s-light and p-light—by a polarizing beam splitter. These two rows of linear light are then magnified by a combination of a first lens 120 and a first microscope objective 130 and illuminate the same area of ​​interest on the surface of the object under test, forming two different fields of view for detection. After the two lines of illumination light are reflected by the surface of the object under test, their polarization states remain unchanged. They enter the second microscope objective 230 and the second lens 220 in the imaging module 200 and are magnified again. Then, they are selectively separated by a polarizing beam splitter, so that the line light WL1 (s-light) is imaged in the industrial camera 1 and the line light WL2 (p-light) is imaged in the industrial camera 2, realizing simultaneous imaging and detection of dual fields of view.

[0052] In the two embodiments above, by using laser light sources or broadband light sources with different wavelengths or polarization states as illumination sources, and adapting them with dichroic mirrors or polarizing beam splitters of different functions, two lines of light with different spectra or polarization states are separated. This allows for more effective identification and analysis of the structural features of the surface of the object under test. These two lines of light illuminate the same area of ​​interest on the surface of the object under test, forming two different fields of view for detection. WL1 is the illumination line light emitted by light source A, which is captured and imaged by industrial camera 1; WL2 is the illumination line light emitted by light source B, which is captured and imaged by industrial camera 2. This achieves simultaneous imaging of dual fields of view, thereby reducing blind spots, covering a wider field of view, improving the overall coverage of the system, and significantly increasing the detection speed. After being reflected by the surface of the object under test, the two lines of light enter the imaging module 200. The industrial cameras in the imaging module 200 can be high-frame-rate line scan cameras or ROI mode area scan cameras. The two industrial cameras simultaneously capture image information within different spectral or polarization state ranges, acquiring global information of the surface of the object under test in real time at high speed, realizing high-speed line scanning function, and avoiding image blurring caused by high-speed movement of the object.

[0053] It is understandable that the methods of controlling the movement of the test object and the image acquisition by the imaging module are not unique. In one embodiment, the control module controls the imaging module 200 to perform image acquisition by exposure according to a set period. The control module also controls the displacement of the test object along a preset scanning path within the set period, which is consistent with the width of the region of interest of the incoherent line light incident on the test object in the direction of the preset scanning path, so that the region of interest corresponding to each image acquisition is continuous and non-overlapping in the direction of the preset scanning path. The specific value of the set period is not unique and can be set according to actual needs.

[0054] Specifically, if the optical paths of the two incoherent line beams are made different by adjusting the slit element 150, that is, the images of the two line beams on the object under test do not overlap, the width of the region of interest in the preset scanning path direction will increase compared to the current single-source illumination detection scheme using dual-source illumination, for example, becoming twice that of the single-source illumination scheme. Figure 8 As shown, assuming a single-source illumination detection scheme, source A provides illumination, the step displacement of the object under test in each cycle is S, and industrial camera 1 performs image acquisition and data conversion processing in each cycle. Therefore, in order to ensure the area of ​​interest is continuous and non-overlapping along the preset scanning path direction, this application can set the step displacement of the object under test in each cycle to 2S, such as... Figure 5 As shown, two industrial cameras acquire and process images of the corresponding region of interest in each cycle. Here, "stage" represents the platform supporting the object under test, and its control timing is the displacement timing of the object under test. Figure 7As shown in Scheme 1, each black frame represents a region of interest. Two light sources are used for illumination, and the optical paths of the two incoherent line lights generated are different. Then, images are acquired on continuous and non-overlapping regions of interest in the direction of a preset scanning path. Compared with the traditional single-light source illumination detection scheme, the detection speed can be improved. Figure 9 The scheme in the diagram is a schematic diagram of image acquisition of the region of interest of the test object in the single-source illumination detection of the existing technology.

[0055] If the optical paths of two incoherent line beams are made to coincide by adjusting the slit element 150, that is, the two line beams overlap on the object under test, then the width of the region of interest in the preset scanning path direction can be considered constant compared to the current single-source illumination detection scheme using dual-source illumination. Similarly, assuming that the step displacement of the object under test in each cycle is S in the single-source illumination detection scheme, this application can also use the same step displacement of the object under test in each cycle, such as... Figure 6 As shown. Figure 7 As shown in Scheme 3, each black frame represents a region of interest. Two light sources are used for illumination, and the optical paths of the two incoherent line lights generated are made to coincide. Then, images are acquired on continuous and non-overlapping regions of interest in the direction of a preset scanning path. Compared with the traditional single-light source illumination detection scheme, the moving speed of the object under test can be kept constant. However, the detection accuracy can be improved by using two different light sources to scan and acquire images at the same position of the object under test.

[0056] In one embodiment, the control module controls the imaging module 200 to perform image acquisition by exposure according to a set cycle. The control module also controls the displacement of the object under test (DUT) along a preset scanning path within the set cycle to be less than the width of the region of interest (ROI) of the DUT incident on the DUT in the preset scanning path direction, so that the ROI corresponding to each image acquisition is continuous and at least partially overlapped in the preset scanning path direction. It is understood that regardless of whether the optical paths of multiple ROI lines coincide due to the slit element 150, the ROI in each cycle in the preset scanning path direction can be made to continuously and at least partially overlap by controlling the moving speed of the DUT; for example, it can overlap by half, or overlap by less or more.

[0057] Specifically, taking the example of slit element 150 causing different optical paths for incoherent line beams, i.e., the images of the two line beams on the object under test do not overlap, the dual-source illumination method used in this application increases the width of the region of interest in the preset scanning path direction compared to the current single-source illumination detection scheme, for example, becoming twice that of the single-source illumination scheme. Similarly, assuming that in the single-source illumination detection scheme, the step displacement of the object under test in each cycle is S, such as... Figure 8As shown. Therefore, in order to ensure that the region of interest is continuous and overlaps along the preset scanning path direction, this application can set the step displacement of the object under test in each cycle to any value between (0, 2S). For example... Figure 7 As shown in Scheme 2, each black and red frame represents a region of interest (the black and red frames in the figure are only used to clearly show that two adjacent regions of interest overlap, and the color difference has no other limiting effect). Multiple light sources are used for illumination and the optical paths of incoherent line lights are made different. Then, images are acquired on the partially overlapping regions of interest in the direction of the preset scanning path.

[0058] In this embodiment, at least two incoherent line lights include a first line light and a second line light arranged in parallel; the scanning area of ​​the first line light in the current region of interest overlaps with the scanning area of ​​the second line light in the previous consecutive region of interest. Specifically, continuing to refer to... Figure 7 Option two involves setting the step displacement of the object under test to S, with a 50% overlap between two consecutive regions of interest. This allows light with different characteristics from the two consecutive regions of interest to illuminate the same position on the object under test, effectively scanning each linear scanning region twice at different wavelengths or polarization states to obtain information, resulting in greater accuracy after image fusion. This setup effectively scans each region of interest twice using different light sources, maintaining the same scanning speed as the single-source illumination detection scheme but significantly improving detection accuracy. It is understood that in other embodiments, the first linear scanning region of the current region of interest can also be located between two linear scanning regions of the previous region of interest, meaning that the linear scanning regions of the 1st, 3rd, 5th, 7th, 9th, ... regions of interest overlap, and the linear scanning regions of the 2nd, 4th, 6th, 8th, 10th, ... regions of interest also overlap, similarly improving detection accuracy.

[0059] In addition, the illumination module 100 also includes an image acquisition unit, and the imaging module 200 also includes a light source. In the imaging module 200, the second functional beam splitter 210 separates the illumination light emitted by the corresponding light source into line light with different characteristics and transmits it to the object under test in the same direction. In the illumination module 100, the first functional beam splitter 110 separates the line light reflected by the object under test and transmits the line light with different characteristics to the corresponding image acquisition unit. After the positions of the light source and the image acquisition unit are interchanged, the functions of the first functional beam splitter 110 and the second functional beam splitter 210 are also interchanged.

[0060] Specifically, an image acquisition device can be added to the first housing 101 of the lighting module 100, or the location where the fiber optic mounting interface is set can be replaced with an image acquisition device; similarly, a fiber optic mounting interface can be added to the second housing 201 of the imaging module 200, or the location where the image acquisition device is installed can be replaced with a fiber optic mounting interface. In this embodiment, the positions of the light source and industrial camera can be adjusted and replaced according to different application requirements (e.g., the positions of industrial cameras 1 and 2 and fiber optic mounting interfaces a and b can be interchanged). By adjusting the positions of the light source and industrial camera, the incident angle and distribution of light can be optimized, thereby improving image clarity and contrast, reducing unnecessary light spots and reflections, making the system more flexible and efficient, meeting different application requirements, and improving the system's measurement accuracy and image quality.

[0061] The triangulation optical measurement system provided in this application has the following advantages:

[0062] Advantage 1: Multispectral detection

[0063] The three-dimensional contour information of the surface of the object under test is analyzed by using lasers of different wavelengths or broadband light sources. Wavelength-selective spectroscopic elements (such as dichroic mirrors) are used for wavelength separation. Light of different spectra is reflected from the surface of the object under test and simultaneously enters different industrial cameras for imaging. Different materials have different spectral responses at different wavelengths. Multispectral detection can effectively distinguish the reflection information of different materials at different wavelengths and obtain richer surface feature information of the object under test.

[0064] Advantage 2: Polarization imaging detection

[0065] The three-dimensional contour information of the surface of the object under test is analyzed using lasers or broadband light sources with different polarization states. Polarization state separation is performed using a beam splitter with polarization state selectivity (such as a polarizing beam splitter prism). Light with different polarization states is reflected from the surface of the object under test and simultaneously enters different industrial cameras for imaging. Different materials have different polarization reflection characteristics. Polarization imaging detection can effectively enhance image contrast and color saturation, more effectively highlight specific structures or features, and improve image quality.

[0066] Advantage 3: High-speed detection

[0067] Using lasers or broadband light sources of different wavelengths or polarization states as illumination sources, the light passes through slit elements at different slit positions to form two lines of linear light. These two lines of light are then separated into two lines of light with different spectra or polarization states by a functionally selective beam-splitting element (such as a dichroic mirror or a polarizing beam-splitter). These two lines of light illuminate the same area of ​​interest on the surface of the object under test, forming two different fields of view for detection. This achieves simultaneous imaging with dual fields of view, reducing blind spots, covering a wider field of view, improving the overall coverage of the system, and significantly increasing detection speed. After reflection from the surface of the object under test, the two lines of light enter the imaging end, which uses a high-frame-rate linear scan camera or a region-of-in-area (ROI) mode area scan camera. The two industrial cameras simultaneously capture image information within different spectral or polarization state ranges, acquiring global information about the surface of the object under test in real time at high speed.

[0068] Advantage 4: High flexibility and scalability

[0069] In semiconductor testing, different materials require different wavelengths or polarization states of light for detection due to their physical and chemical properties. This application features a highly flexible and scalable architecture, allowing for rapid adjustment and expansion of system functions to meet diverse application needs. For example, by combining the optical properties of different test surface materials with the specific target to be detected, the illumination module selects a suitable light source, and the imaging module selectively equips different functional beam-splitting elements (such as dichroic mirrors or polarizing beam-splitting prisms), enabling more effective identification and analysis of the structural features of the test surface. Furthermore, the positions of the light source and industrial camera in this application can be adjusted and interchanged (e.g., the positions of industrial camera 1 and fiber optic mounting interface b can be swapped). By adjusting the positions of the light source and camera, the incident angle and distribution of light can be optimized, thereby improving image clarity and contrast, reducing unnecessary light spots and reflections, making the system more flexible and efficient, meeting different application requirements, and improving the system's measurement accuracy and image quality.

[0070] Advantage 5: High-precision detection

[0071] Using microscope objectives with different magnifications for illumination and imaging in the imaging and illumination modules, the optical characteristics of the microscope objectives, such as magnification, NA (aperture range), and transmittance, affect the overall image quality and detection accuracy. By considering the structural features of the object's surface at different dimensions, and rationally selecting and combining microscope objectives with different magnifications, imaging and illumination can be optimized. This changes the linewidth of the illumination source and the number of pixels corresponding to the linelight image in the industrial camera, thereby obtaining more refined and accurate images and improving the overall detection accuracy of the system.

[0072] 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.

[0073] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A triangulation optical measurement system, characterized in that, include: An illumination module includes a first functional beam splitter and at least two light sources. The first functional beam splitter splits the illumination light emitted by the at least two light sources into at least two incoherent line beams with different characteristics, which are incident on the surface of the object under test in the same direction. The first functional beam splitter is an element that reflects and transmits at least two beams of light with different characteristics and then emits them in the same direction without interference, so as to generate two incoherent line beams to detect the object under test simultaneously. The illumination module also includes a slit element disposed between the first functional beam splitter and the light sources. The illumination light emitted by each light source passes through the corresponding slit element and forms a line beam, which is then output to the first functional beam splitter. The position of the slit of the slit element is adjustable along the width direction so that the optical paths of the incoherent line beams are different or coincident. Imaging module.

2. The system according to claim 1, characterized in that, The illumination module further includes a first lens and a first microscope objective. The first functional beam splitter, the first lens, and the first microscope objective are arranged sequentially along the optical path. The incoherent line light output by the first functional beam splitter passes through the first lens and the first microscope objective and is incident on the surface of the object to be tested.

3. The system according to claim 1, characterized in that, The first functional beam splitter splits the illumination light into incoherent line light of different wavelengths or different polarization states.

4. The system according to claim 3, characterized in that, The imaging module includes at least one image acquisition unit for simultaneously acquiring reflected images of at least two incoherent line lights as a periodic region of interest image. The system also includes a control module for periodically acquiring images of the region of interest on the object under test when the object under test is displaced along a preset scanning path. The system also includes a first housing, and the first functional beam splitter is disposed within the first housing.

5. The system according to claim 4, characterized in that, The control module controls the imaging module to perform image acquisition by exposure according to a set period. The control module also controls the displacement of the object under test along the preset scanning path within the set period, which is consistent with the width of the region of interest of the object under test incident on the incoherent line light in the preset scanning path direction, so that the region of interest corresponding to each image acquisition is continuous and non-overlapping in the preset scanning path direction.

6. The system according to claim 4, characterized in that, The control module controls the imaging module to perform image acquisition by exposure according to a set period. The control module also controls the displacement of the object under test along the preset scanning path within the set period to be less than the width of the region of interest of the object under test incident on the incoherent line light in the preset scanning path direction, so that the region of interest corresponding to each image acquisition is continuous and at least partially overlapped in the preset scanning path direction.

7. The system according to claim 6, characterized in that, At least two of the incoherent line lights include a first line light and a second line light arranged in parallel; the scanning area of ​​the first line light in the current region of interest overlaps with the scanning area of ​​the second line light in the previous consecutive region of interest.

8. The system according to claim 4, characterized in that, The number of image acquisition devices is two or more, and the imaging module also includes a second functional beam splitter. The second functional beam splitter transmits or reflects the line light reflected by the object under test, separates incoherent line light with different characteristics, and transmits it to the corresponding image acquisition device.

9. The system according to claim 8, characterized in that, The imaging module further includes a second lens and a second microscope objective. The second microscope objective, the second lens, and the second functional beam splitter are arranged sequentially along the optical path. The line light reflected by the object under test is transmitted through the second microscope objective and the second lens to the second functional beam splitter for transmission or reflection, separating incoherent line light with different characteristics and transmitting it to the corresponding image acquisition device.

10. The system according to claim 8, characterized in that, The first functional beam splitter is a dichroic mirror or a polarizing beam splitter, and the second functional beam splitter is a dichroic mirror or a polarizing beam splitter.

11. The system according to claim 8, characterized in that, The illumination module also includes an image acquisition unit, and the imaging module also includes a light source; in the imaging module, the second functional beam splitter separates the illumination light emitted by the corresponding light source into line light with different characteristics and transmits them to the object under test; In the illumination module, the first functional beam splitter separates the linear light reflected by the object under test, and transmits the linear light with different characteristics to the corresponding image acquisition unit.

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