Triangular optical measurement system

Abstract

The application relates to a triangular optical measurement system, comprising: an illumination module, the illumination module comprising a first functional light splitting element and at least two light sources, the first functional light splitting element being used for splitting the illumination light emitted by the at least two light sources to form at least two non-coherent line lights with different characteristics to be incident on the surface of a to-be-measured object along the same direction; an imaging module, the imaging module comprising at least one image collector, and being used for simultaneously collecting the reflection images of the at least two non-coherent line lights as a periodical image of a region of interest; and a control module, the control module being used for periodically collecting the image of the region of interest on the to-be-measured object when the to-be-measured object is displaced along a preset scanning path, so that the image information of the non-coherent line lights with different characteristics on the surface of the to-be-measured object can be captured, a more fine and accurate image can be obtained, and the detection precision or the detection efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical detection, in particular to a triangular optical measurement system. BACKGROUND

[0002] The 3D line scanning optical detection system is an optical system for high-precision three-dimensional measurement and detection. A laser or high-power LED line light source and an industrial camera are in a fixed relative position at a certain angle to perform line scanning on the surface of an object. The industrial camera captures the position change of the reflection points of the light on the surface of the object, and calculates the three-dimensional coordinates of each point on the surface of the measured object in real time through the triangulation method. Compared with the traditional contact measurement method, the 3D line scanning optical detection system has the advantages of non-contact and non-damage, is suitable for measuring complex shapes or surface-sensitive objects, can quickly and efficiently generate three-dimensional topographic information of the surface of the object, and is widely used in industrial detection such as semiconductor wafer detection, photoresist thickness measurement, and microstructure topography measurement of semiconductor components. However, in the traditional optical detection system, the amount of information obtained is insufficient, and there are disadvantages of low detection precision or low detection efficiency. SUMMARY

[0003] Therefore, it is necessary to provide a triangular optical measurement system that can improve the detection precision or the detection efficiency.

[0004] A triangular optical measurement system comprises:

[0005] An illumination module, which comprises a first functional light splitting element and at least two light sources, and is configured to split the illumination light emitted by the at least two light sources into at least two non-coherent line lights with different characteristics and make the at least two non-coherent line lights with different characteristics incident on the surface of a measured object along the same direction;

[0006] An imaging module, which comprises at least one image collector and is configured to simultaneously collect reflection images of the at least two non-coherent line lights as a periodical image of a region of interest on the measured object;

[0007] A control module, which is configured to periodically collect the image of the region of interest on the measured object when the measured object moves along a preset scanning path.

[0008] In one embodiment, the control module controls the imaging module to collect images according to a set period of exposure, and controls the displacement of the measured object along the preset scanning path within the set period to be consistent with the width of the region of interest on the measured object in the direction of the preset scanning path, so that the corresponding region of interest in each image collection is continuous and non-overlapping in the direction of the preset scanning path.

[0009] In one of the embodiments, the control module controls the imaging module to perform image acquisition according to a set period of exposure, and controls displacement of the object to be measured along a preset scanning path within the set period of exposure to be less than a width of a region of interest of the object to be measured in a direction of the preset scanning path under the incidence of the non-coherent line light, so that the corresponding region of interest in the direction of the preset scanning path is continuous and at least partially overlapped in each image acquisition.

[0010] In one of the embodiments, the at least two non-coherent line lights include a first line light and a second line light arranged in parallel; a first line light scanning region in a current region of interest overlaps with a second line light scanning region in a last continuous region of interest.

[0011] In one of the embodiments, the illumination module further includes a slit element arranged between the first functional light splitting element and the light source; the illumination light emitted by each of the light sources is output as a line light to the first functional light splitting element after passing through the corresponding slit element.

[0012] In one of the embodiments, the slit of the slit element is adjustable in position along a width direction, so that the optical paths of the non-coherent line lights are different or coincident.

[0013] In one of the embodiments, the number of the image acquisition devices is more than two; the imaging module further includes a second functional light splitting element; the second functional light splitting element transmits or reflects the line light reflected by the object to be measured, separates the non-coherent line lights with different characteristics, and transmits the non-coherent line lights to the corresponding image acquisition devices.

[0014] In one of the embodiments, the illumination module further includes a first lens and a first microscope objective; the first functional light splitting element, the first lens, and the first microscope objective are arranged in sequence along an optical path; the non-coherent line light output by the first functional light splitting element is incident on the surface of the object to be measured after passing through the first lens and the first microscope objective.

[0015] In one of the embodiments, the imaging module further includes a second lens and a second microscope objective; the second microscope objective, the second lens, and the second functional light splitting element are arranged in sequence along an optical path; the line light reflected by the object to be measured is transmitted to the second functional light splitting element through the second microscope objective and the second lens to be transmitted or reflected, so that the non-coherent line lights with different characteristics are separated and transmitted to the corresponding image acquisition devices.

[0016] In one of the embodiments, the first functional light splitting element is a dichroic mirror or a polarization light splitting element; the second functional light splitting element is a dichroic mirror or a polarization light splitting element.

[0017] In one of the embodiments, the illumination module further comprises an image collector, and the imaging module further comprises a light source; in the imaging module, the second functional light splitting element separates the illumination light emitted by the corresponding light source into linear light of different characteristics and transmits the linear light to the object to be measured; in the illumination module, the first functional light splitting element separates the linear light reflected by the object to be measured and obtains linear light of different characteristics and transmits the linear light to the corresponding image collector.

[0018] In the above triangular optical measurement system, the illumination module comprises a first functional light splitting element and at least two light sources, and the first functional light splitting element is used to split the illumination light emitted by the at least two light sources into at least two non-coherent linear lights of different characteristics and transmit the linear lights to the surface of the object to be measured along the same direction; the imaging module comprises at least one image collector, which is used to simultaneously collect the reflection images of the at least two non-coherent linear lights as a periodic image of the region of interest on the object to be measured. The control module is used to periodically collect the image of the region of interest on the object to be measured when the object to be measured is displaced along a preset scanning path, so that the image information of the non-coherent linear light of different characteristics on the surface of the object to be measured can be captured, a more fine and accurate image can be obtained, and the detection accuracy or detection efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the triangular optical measurement system in one embodiment;

[0020] Figure 2 It is a structural schematic diagram of the triangular optical measurement system in one embodiment;

[0021] Figure 3 It is a structural schematic diagram of the triangular optical measurement system in another embodiment;

[0022] Figure 4 It is a linear scanning schematic diagram of the surface of the object to be measured in one embodiment;

[0023] Figure 5 It is an illumination and imaging timing schematic diagram in one embodiment;

[0024] Figure 6 It is an illumination and imaging timing schematic diagram in another embodiment;

[0025] Figure 7 It is an image collection schematic diagram of the region of interest on the object to be measured in some embodiments;

[0026] Figure 8 It is an illumination and imaging timing schematic diagram of single-light-source illumination detection;

[0027] Figure 9 It is an image collection schematic diagram of the region of interest on the object to be measured in the single-light-source illumination detection in the prior art. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and not to limit the present application.

[0029] 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 in the description herein is for describing specific embodiments only and is not intended to be limiting of the present application.

[0030] It can be understood that, in the following embodiments, “connection” should be understood as “electrical connection”, “communication connection” and the like if the circuits, modules, units and the like connected with each other have transmission of electrical signals or data.

[0031] As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. It should also be understood that the term “comprising” or “including” or “having” and the like, designate the presence of stated features, integers, methods, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, methods, operations, components, parts, or combinations thereof.

[0032] In one embodiment, as shown in Figure 1 and Figure 2 A triangular optical measurement system is provided, including an illumination module 100, an imaging module 200 and a control module (not shown in the figure), the illumination module 100 includes a first functional light splitting element 110 and at least two light sources, the first functional light splitting element 110 is used to split the illumination light emitted by the at least two light sources to form at least two different characteristic non-coherent line lights incident to the surface of the object to be measured along the same direction (referring to the transmission direction being approximately the same, not requiring to be completely parallel); the imaging module 200 includes at least one image collector, which is used to simultaneously collect the reflection images of the at least two non-coherent line lights as a cycle of the image of the region of interest on the object to be measured. The control module is used to periodically collect the image of the region of interest on the object to be measured when the object to be measured produces displacement along the preset scanning path.

[0033] Wherein, the object to be measured can be a wafer or other products that need to be detected for surface image. The number of light sources can be two or more, for example, including light source A, light source B, etc. The light source can be a constant light source, continuously providing illumination light, or a stroboscopic light source, providing illumination light once in a cycle. The type of illumination light emitted by the light source is not unique, for example, the light source can be a laser light source of different wavelengths or different polarization states, or a wide-spectrum light source of different wavelengths or different polarization states, etc.

[0034] Correspondingly, the first functional light splitting element 110 splits the illumination light of each light source into non-coherent line light with different characteristics, which can be non-coherent line light with different wavelengths or different polarization states. Referring to Figure 2 The first functional light splitting element 110 in the embodiments of the present application can specifically adopt a dichroic mirror or a polarization light splitting element. The polarization light splitting element can specifically adopt a polarization light splitting prism or a polarization light splitting sheet. The dichroic mirror can specifically adopt a short-wave pass dichroic mirror, a long-wave pass dichroic mirror, a multi-band dichroic mirror, etc. The short-wave pass dichroic mirror has high transmissivity for light below the cutoff wavelength and high reflectivity for light above the cutoff wavelength; the long-wave pass dichroic mirror has high transmissivity 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 wavelength bands, for example, high transmissivity for the wavelength band between the cutoff wavelength and the starting wavelength and high reflectivity for other wavelength bands.

[0035] The above specific examples only illustrate the first functional light splitting element 110. In other embodiments, as long as the light beams with two different wavelengths (or polarization states) respectively reflected and transmitted by the reflecting surface and the transmitting surface of the functional light splitting element can be reflected and transmitted along the same direction to the object to be measured.

[0036] It should be emphasized that the first functional light splitting element 110 in the present application is different from the ordinary light splitting prism or light splitting sheet, which only has a single light splitting function and does not have the characteristics of selectively reflecting or transmitting light with different wavelengths or polarization states. However, the first functional light splitting element 110 in the present application can reflect and transmit at least two light beams with different characteristics along the same direction without interference (or with low coherence), so as to generate two non-coherent line lights and detect the object to be measured at the same time, thereby improving the detection efficiency.

[0037] The number of image collectors can be one or more, for example, including an industrial camera 1, an industrial camera 2, etc. The type of image collector is not unique and can be a line array camera, a plane array camera, etc. When the number of image collectors is one, the image collector collects the reflection images of at least two non-coherent line lights with different characteristics. When the number of image collectors is more than one, each image collector can collect the reflection images of one or more non-coherent line lights with different characteristics. In the present embodiment, multiple image collectors are used to collect line lights with different wavelengths / polarization states, which can better form images.

[0038] The control module is connected to the imaging module and a carrier platform on which the object to be measured is placed. The control module controls the carrier platform to move the object to be measured along a preset scanning path to generate displacement (i.e., a preset step displacement), and controls the imaging module to perform exposure and collect images to obtain images of a region of interest on the object to be measured. The images of the region of interest are images obtained by collecting images of the region of interest on the object to be measured in each cycle. The region of interest can be determined according to the FOV (field of view) of the image collector. For example, when the image collector is a linear array camera, the FOV is 1*n or 2*n pixel regions, and the region of interest can be set to m or m / 2 FOVs. In each cycle, the light source flashes once or is always on, the linear array camera performs multiple exposures, and the images of all m*n pixels of the region of interest in the cycle are obtained to obtain the images of the region of interest. When the image collector is a planar array camera, the FOV is relatively large (which can be understood as being similar to a square), and the shape of each frame of image in general triangulation is a strip-shaped region of interest corresponding to the shape of the linear light. In order to ensure the continuity of the strip-shaped region of interest, the preset step displacement is generally smaller than the FOV width in the displacement direction. In this way, the two consecutive FOVs overlap, and a ROI (region of interest) region containing a strip-shaped linear light in the FOV can be selected as the region of interest. The ROI region is sequentially scanned, i.e., in a ROI scanning mode. The region of interest can overlap or not overlap. It can be understood that if the image collector is a general linear array camera, the region of interest is the region in which the multiple exposure images in a cycle are spliced. If the image collector is a TDI camera, the region of interest can also be the FOV or the ROI region of the TDI camera.

[0039] In each cycle, each light source flashes once, and the control module controls each image collector to perform one or more exposures to collect the reflection image of the incoherent linear light on the surface of the object to be measured to obtain the images of the region of interest in the cycle, and capture the feature information of the surface of the object to be measured in real time. By combining the images of the region of interest obtained in different cycles, the different heights of the surface of the object to be measured can be analyzed. By using multiple light sources to provide illumination light and using the first functional light splitting element 110 to split the illumination light emitted by each light source to form incoherent linear light with different characteristics, the image information of the incoherent linear light with different characteristics on the surface of the object to be measured can be captured, and more accurate and precise images can be obtained.

[0040] In addition, the control module is also used to determine the three-dimensional height information of the object to be measured in the current region of interest based on the reflection image information of the linear light in the region of interest. Further, after the adjacent regions of interest are sequentially spliced and processed, a complete image of the object to be measured can be formed (see Figure 4 ), which is used to analyze the three-dimensional height information or two-dimensional size information of the surface of the object to be measured, and the like.

[0041] In one embodiment, as Figure 2As shown in the figure, the illumination module 100 further comprises a first lens 120 and a first microscope objective 130, the first functional light splitting element 110, the first lens 120 and the first microscope objective 130 are sequentially arranged along the optical path, and the incoherent line light output by the first functional light splitting element 110 is incident on the surface of the object to be measured after passing through the first lens 120 and the first microscope objective 130.

[0042] As shown in the figure, Figure 1 and Figure 2 As shown in the figure, the illumination module 100 further comprises a first housing 101, the first functional light splitting element 110 and the first lens 120 are arranged in the first housing 101, and the first housing 101 is provided with a fiber mounting interface, such as fiber mounting interface a, fiber mounting interface b, etc., which is connected to the corresponding light source through the optical fiber. Further, the illumination module 100 can further comprise a first objective converter 140, the first objective converter 140 is arranged on the first housing 101, the number of the first microscope objective 130 is multiple, and the magnification of each first microscope objective 130 is different, each first microscope objective 130 is arranged on the first objective converter 140, and the first objective converter 140 can drive each first microscope objective 130 to rotate relative to the first housing 101. The first lens 120 and the first microscope objective 130 in the illumination module 100 form an infinite distance correction optical system, and different magnifications of the first microscope objective 130 can be reasonably selected and combined according to actual needs to optimize the illumination, change the line width of the illumination light source through the first microscope objective 130, and realize the zoom function of the imaging illumination.

[0043] As shown in the figure, Figure 2 and Figure 3 As shown in the figure, the illumination module 100 can further comprise a slit element 150 arranged between the first functional light splitting element 110 and the light source, and the illumination light emitted by each light source forms a line light output to the first functional light splitting element 110 through the corresponding slit element 150. Specifically, the slit element 150 can adopt a grating sheet, and the slit element 150 can be arranged between the fiber mounting interface and the first functional light splitting element 110. The light source transmits the illumination light to the fiber mounting interface through the optical fiber, and the light spot becomes a long and narrow line after passing through the slit element 150 with different slit positions, forming two rows of line light.

[0044] The slits of the slit element 150 are adjustable along their width direction, allowing the optical paths of incoherent line beams to differ or overlap. 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 hitting 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.

[0045] 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.

[0046] 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.

[0047] In addition, the imaging module 200 further comprises a second shell 201, the second lens 220 and the second functional light splitting element 210 are arranged in the second shell 201, and the image collector is arranged on the second shell 201. Figure 1 As shown in the figure, the imaging module 200 can further comprise a second objective converter 240, the second objective converter 240 is arranged on the second shell 201, the number of the second microscopic objective 230 is multiple, and the magnification of each second microscopic objective 230 is different, each second microscopic objective 230 is arranged on the second objective converter 240, and the second objective converter 240 can drive each second microscopic objective 230 to rotate relative to the second shell 201. According to actual needs, the second microscopic objectives 230 with different magnifications can be reasonably selected and combined to optimize imaging, so as to ensure the best imaging accuracy and resolution.

[0048] By arranging multiple microscopic objectives with different magnifications in the illumination module 100 and the imaging module 200 respectively, and using the corresponding objective converters to realize illumination and imaging with different magnifications, for the structure features of different sizes on the surface of the object to be measured, the microscopic objectives with different magnifications can be reasonably selected and combined to optimize imaging and illumination, so as to ensure the best imaging accuracy and resolution.

[0049] In an embodiment, taking the dichroic mirror as an example for the first functional light splitting element 110 and the second functional light splitting element 210, the light source can be a laser light source with different wavelengths or a wide-spectrum light source. Figures 1 to 3 As shown in the figure, in the illumination module 100, the illumination optical fibers are respectively arranged in the optical fiber mounting interface a and the optical fiber mounting interface b, and the slit elements 150 are respectively arranged between the optical fiber mounting interface a, the optical fiber mounting interface b and the first functional light splitting element 110. The slit positions of the two slit elements 150 are different, the slit widths can be the same or different, and the slit width can be selected according to the characteristic size of the surface of the object to be measured. The illumination light emitted by the light sources A and B is introduced into the first shell 101 through the illumination optical fibers, and in this process, the light passes through the slit elements 150 with different slit positions to form two rows of linear light, and the two rows of linear light are separated into two rows of linear light with different spectra through the dichroic mirror. After the two rows of linear light are combined and magnified by the first lens 120 and the first microscopic objective 130, they irradiate the same attention area on the surface of the object to be measured, forming two rows of different field detection, as shown in the figure. Figure 4 After the two rows of illumination linear light are reflected by the surface of the object to be measured, they enter the second microscopic objective 230 and the second lens 220 in the imaging module 200 to be magnified again, and then are selectively separated through the dichroic mirror, so that the linear light WL1 is imaged in the industrial camera 1, and the linear light WL2 is imaged in the industrial camera 2, realizing double-view simultaneous imaging detection.

[0050] In another embodiment, taking the polarizing beam splitter as an example of the first functional light splitting element 110 and the second functional light splitting element 210, the light source can be a laser light source with different polarization states or a wide-spectrum light source. If the object to be measured is a polarized material, the use of polarization imaging detection can enhance the image contrast and color saturation, more effectively highlight specific structures or features, and improve the imaging quality. Similarly, referring to Figures 1 to 3 In the illumination module 100, the illumination optical fibers are respectively installed in the optical fiber installation interface a and the optical fiber installation interface b, and the slit elements 150 are respectively added between the optical fiber installation interface a, the optical fiber installation interface b and the first functional light splitting element 110. The slit positions of the two slit elements 150 are different, and the slit widths can be the same or different. The slit width can be selected according to the characteristic size of the surface of the object to be measured. The illumination light emitted by the light sources A and B is introduced into the first housing 101 through the illumination optical fibers. In this process, the light passes through the slit elements 150 with different slit positions to form two rows of linear light. The two rows of linear light are separated into two rows of linear light with different polarization states, s light and p light, by the polarizing beam splitter. After the combination of the first lens 120 and the first microscope objective 130, the two rows of linear light are irradiated on the same area of interest on the surface of the object to be measured, forming two rows of different field detection. After the two rows of linear illumination light are reflected by the surface of the object to be measured, the polarization state remains unchanged, and the light enters the second microscope objective 230 and the second lens 220 in the imaging module 200 to be magnified again. The linear light WL1 (s light) is imaged on the industrial camera 1, and the linear light WL2 (p light) is imaged on the industrial camera 2, realizing double-view simultaneous imaging detection.

[0051] In the above two embodiments, by using laser light sources or wide-spectrum light sources with different wavelengths or different polarization states as illumination light sources, and by adapting dichroic mirrors or polarizing beam splitters with different functions, two rows of linear light with different spectra or different polarization states can be separated. The two rows of linear light are irradiated on the same area of interest on the surface of the object to be measured, forming two rows of different field detection. WL1 is the illumination linear light emitted by the light source A, which is captured and imaged by the industrial camera 1. WL2 is the illumination linear light emitted by the light source B, which is captured and imaged by the industrial camera 2, realizing double-view simultaneous imaging. This reduces the viewing angle blind area, covers a larger viewing angle range, improves the overall coverage rate of the system, and greatly improves the detection speed. The two rows of linear light enter the imaging module 200 after being reflected by the surface of the object to be measured. The industrial cameras in the imaging module 200 can be high-frame-rate linear array cameras or ROI mode area array cameras. The two industrial cameras simultaneously capture image information within different spectral or polarization state ranges, and real-time high-speed acquisition of global information of the surface of the object to be measured is realized, achieving high-speed line scanning function and avoiding image blur caused by high-speed movement of the object.

[0052] It can be understood that the way of controlling the movement of the object under test by the control module and controlling the image acquisition by the imaging module is not unique. In an embodiment, the control module controls the imaging module 200 to perform image acquisition according to a set period of exposure, and the control module also controls the displacement of the object under test along the preset scanning path generated within the set period to be consistent with the width of the region of interest of the object under test in the direction of the preset scanning path when the incoherent line light is incident on the region of interest, so that the corresponding region of interest in each image acquisition is continuous and non-overlapping in the direction of the preset scanning path. The specific value of the set period is also not unique and can be set according to actual needs.

[0053] Specifically, if the optical paths of the two incoherent line lights are different by adjusting the slit element 150, i.e., the images of the two line lights on the object under test are not overlapped, the application adopts double light source illumination. Compared with the current single light source illumination detection scheme, the width of the region of interest in the direction of the preset scanning path will increase, for example, to twice that of the single light source illumination scheme. As shown in Figure 8 , it is assumed that in the single light source illumination detection scheme, light source A provides illumination, and the step displacement of the object under test in each period is S, and the industrial camera 1 performs image acquisition and data conversion processing in each period. In order to make the region of interest continuous and non-overlapping in the direction of the preset scanning path, the application can set the step displacement of the object under test in each period to 2S, as shown in Figure 5 , two industrial cameras perform image acquisition and data conversion processing on the corresponding region of interest images in each period, where stage represents the object support platform supporting the object under test, and its control timing is the displacement timing of the object under test. As shown in Figure 7 , scheme one, each black line 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, and then image acquisition is performed on the continuous and non-overlapping regions of interest in the direction of the 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 figure is the image acquisition diagram of the region of interest of the object under test in the single light source illumination detection in the prior art.

[0054] If the optical paths of the two incoherent line lights are overlapped by adjusting the slit element 150, i.e., the two line lights are overlapped on the object under test. Then the application adopts double light source illumination. Compared with the current single light source illumination detection scheme, the width of the region of interest in the direction of the preset scanning path can be considered to remain unchanged. It is also assumed that in the single light source illumination detection scheme, the step displacement of the object under test in each period is S, and the application can also be the step displacement of the object under test in each period S, as shown in Figure 6 . As shown in Figure 7In the third scheme shown in FIG. 3, each black line frame represents a region of interest, two light sources are used for illumination and the optical paths of the two generated incoherent line lights are overlapped, and then image acquisition is performed on the continuous and non-overlapping regions of interest in the preset scanning path direction. Compared with the traditional single light source illumination detection scheme, the moving speed of the object to be detected can be kept unchanged, but the same position of the object to be detected is scanned and acquired using two different light sources, which can improve the detection accuracy.

[0055] In one embodiment, the control module controls the imaging module 200 to perform image acquisition at a set period of exposure, and controls the displacement of the object to be detected along the preset scanning path within the set period to be less than the width of the region of interest in the preset scanning path direction on which the incoherent line light is incident, so that the corresponding region of interest in each image acquisition is continuous and at least partially overlapped in the preset scanning path direction. It can be understood that, whether the slit element 150 overlaps the optical paths of the multiple incoherent line lights or not, the continuous and at least partially overlapped regions of interest in each period in the preset scanning path direction can be achieved by controlling the moving speed of the object to be detected, for example, the overlap can be half, or less or more.

[0056] Specifically, taking the case where the slit element 150 makes the optical paths of the incoherent line lights different, i.e., the images of the two line lights on the object to be detected are not overlapped, the present application uses double light source illumination. Compared with the current single light source illumination detection scheme, the width of the region of interest in the preset scanning path direction will increase, for example, to twice that of the single light source illumination scheme. Also assuming that in the single light source illumination detection scheme, the step displacement of the object to be detected in each period is S, as shown in FIG. 2. Then, in order to make the regions of interest continuous and overlapped in the preset scanning path direction, the step displacement of the object to be detected in each period can be set to any one between (0, 2S). As shown in FIG. 4. Figure 8 Figure 7 In the second scheme shown in FIG. 3, each black line frame and red line frame represents a region of interest (the color distinction in the figure has no other limiting effect, and the black line frame and red line frame are only used to clearly show that the two adjacent regions of interest are overlapped), multiple light sources are used for illumination and the optical paths of the incoherent line lights are different, and then image acquisition is performed on the partially overlapped regions of interest in the preset scanning path direction.

[0057] In this embodiment, the at least two incoherent line lights include a first line light and a second line light arranged in parallel; the first line light scanning region in the current region of interest is overlapped with the second line light scanning region in the last continuous region of interest. Specifically, continuing to refer to FIG. 3, the first line light and the second line light are arranged in parallel, and the first line light scanning region in the current region of interest is overlapped with the second line light scanning region in the last continuous region of interest. Figure 7 ​In the second scheme in the first aspect, the step displacement of the object to be detected can be set as S, and there is a half overlap area between two adjacent focus areas, so that the light with different characteristics in the two adjacent focus areas is incident on the same position of the object to be detected, which is equivalent to scanning twice in different wave bands or polarization states for each line light scanning area to obtain information, and the information is more accurate after image fusion. In this way, each focus area is equivalent to being scanned twice by different light sources, and the scanning speed is the same as that of the single light source detection scheme, but the detection accuracy can be effectively improved. It can be understood that in other embodiments, the first line light scanning area of the current focus area can also be located in the middle of the two line light scanning areas of the previous focus area, which is equivalent to that the line light scanning areas of the 1st, 3rd, 5th, 7th, 9th, … focus areas overlap, and the line light scanning areas of the 2nd, 4th, 6th, 8th, 10th, … focus areas overlap, which can also improve the detection accuracy.

[0058] In addition, the illumination module 100 further comprises an image collector, and the imaging module 200 further comprises a light source; in the imaging module 200, the second functional light splitting element 210 separates the illumination light emitted by the corresponding light source into line lights with different characteristics and transmits the line lights to the object to be detected along the same direction; in the illumination module 100, the first functional light splitting element 110 separates the line light reflected by the object to be detected, and transmits the line light with different characteristics to the corresponding image collector. After the positions of the light source and the image collector are interchanged, the functions of the first functional light splitting element 110 and the second functional light splitting element 210 are also interchanged.

[0059] Specifically, the image collector can be newly added to the first shell 101 of the illumination module 100, or the position of the fiber installation interface can be replaced by the image collector; or the fiber installation interface can be newly added to the second shell 201 of the imaging module 200, or the position of the image collector can be replaced by the fiber installation interface. In this embodiment, the positions of the light source and the industrial camera can be adjusted and replaced according to different application requirements (for example, the positions of the industrial cameras 1 and 2 and the fiber installation interfaces a and b can be interchanged). By adjusting the positions of the light source and the industrial camera, the incident angle and distribution of the light can be optimized, so as to improve the definition and contrast of the image, reduce unnecessary light spots and reflections, make the system more flexible and efficient, meet different application requirements, and improve the measurement accuracy and image quality of the system.

[0060] The above-mentioned triangular optical measurement system provided by the present application has the following advantages:

[0061] Advantage 1: Multi-spectral detection

[0062] Different wavelengths of laser or wide spectrum light source are used to analyze the three-dimensional profile information of the surface of the object to be measured, and wavelength separation is performed using a wavelength-selective light splitting element (such as a dichroic mirror). After being reflected by the surface of the object to be measured, light rays of different spectra enter different industrial cameras for imaging at the same time. Different materials have different spectral responses at different wavelengths, and multispectral detection can effectively distinguish the reflection information of different materials at different wavelengths, and obtain more rich feature information of the surface of the object to be measured.

[0063] Advantage 2: Polarization imaging detection

[0064] Different polarization states of laser or wide spectrum light source are used to analyze the three-dimensional profile information of the surface of the object to be measured, and polarization state separation is performed using a polarization state-selective light splitting element (such as a polarization light splitting prism). After being reflected by the surface of the object to be measured, light rays of different polarization states enter different industrial cameras for imaging at the same time. Different materials have different polarization reflection characteristics, and polarization imaging detection can effectively enhance the contrast and color saturation of the image, more effectively highlight specific structures or features, and improve the imaging quality.

[0065] Advantage 3: High-speed detection

[0066] Different wavelengths or different polarization states of laser or wide spectrum light source are used as illumination light source, and light rays pass through a slit element at different slit positions to form two rows of line light. Two rows of line light are separated by a function-selective light splitting element (such as a dichroic mirror or a polarization light splitting prism) to obtain two rows of line light of different spectra or different polarization states. The two rows of line light irradiate the same area of interest on the surface of the object to be measured, form two rows of different field of view detection, realize double field of view simultaneous imaging, reduce the visual angle blind area, cover a larger visual angle range, improve the overall coverage rate of the system, and greatly improve the detection speed. Two rows of line light enter the imaging end after being reflected by the surface of the object to be measured. The imaging end uses a high-frame-rate line array camera or a ROI mode area array camera. Two industrial cameras simultaneously capture image information in different spectral or different polarization state ranges, and real-time high-speed acquire global information of the surface of the object to be measured.

[0067] Advantage 4: High flexibility and scalability

[0068] In semiconductor detection, different materials require different wavelengths or different polarization states of light sources for detection due to their physical and chemical properties. The present application has a highly flexible and scalable architecture, which can quickly adjust and expand system functions according to different application requirements. For example, combined with the optical properties of different surface materials of the measured object and the specific target of the required detection, the illumination module selects the appropriate light source, and the imaging module selectively assembles different functional spectral elements (such as dichroic mirrors or polarization spectral prisms), which can more effectively identify and analyze the structural features of the surface of the measured object. In addition, the positions of the light source and the industrial camera of the present application can be adjusted and replaced with each other (such as the positions of the industrial camera 1 and the fiber mounting interface b can be exchanged with each other), by adjusting the positions of the light source and the camera, the incidence angle and distribution of the light can be optimized, thereby improving the clarity and contrast of the image, reducing unnecessary light spots and reflections, making the system more flexible and efficient, and being able to meet different application requirements, improving the measurement accuracy and image quality of the system.

[0069] Advantage 5: High-precision detection

[0070] When the imaging module and the illumination module use different magnification microscopes for illumination and imaging, the magnification, NA, transmittance and other optical properties of the microscope will affect the overall imaging quality and detection accuracy. Combined with the different size structural features of the surface of the measured object, different magnification microscopes are reasonably selected and combined to optimize imaging and illumination, the line light width of the illumination light source is changed, and the corresponding number of pixels of the line light imaging to the industrial camera is changed, so as to obtain more fine and accurate images and improve the detection accuracy of the entire system.

[0071] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

[0072] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A triangulating optical measurement system, characterized in that The application relates to a light module, an imaging module and a control module. The light module comprises a first functional light splitting element and two or more light sources, the first functional light splitting element is used for splitting light emitted by the at least two light sources into at least two non-coherent line lights with different characteristics and making the at least two non-coherent line lights enter a surface of a to-be-detected object in the same direction; the first functional light splitting element is an element which reflects and transmits the at least two lights with different characteristics and makes the at least two lights exit in the same direction without interference, so that the two non-coherent line lights can be used to detect the to-be-detected object at the same time; the light module further comprises slit elements arranged between the first functional light splitting element and the light sources; light emitted by each light source is output to the first functional light splitting element in the form of a line light after passing through a corresponding slit element; the slit of the slit element is adjustable in the width direction, so that the optical paths of the non-coherent line lights are different or coincide. The imaging module comprises at least one image collector which is used for collecting reflection images of the at least two non-coherent line lights as a periodical image of a region of interest. The control module is used for collecting the image of the region of interest on the to-be-detected object periodically when the to-be-detected object is displaced along a preset scanning path.

2. The system of claim 1, wherein, The control module controls the imaging module to collect the image according to a set exposure period; the control module further controls the displacement of the to-be-detected object along the preset scanning path within the set exposure period, and the displacement is consistent with the width of the region of interest of the to-be-detected object in the preset scanning path direction, so that the corresponding region of interest is continuous and non-overlapping in the preset scanning path direction in each image collection.

3. The system of claim 1, wherein, The control module controls the imaging module to collect the image according to a set exposure period; the control module further controls the displacement of the to-be-detected object along the preset scanning path within the set exposure period, and the displacement is smaller than the width of the region of interest of the to-be-detected object in the preset scanning path direction, so that the corresponding region of interest is continuous and at least partially overlapping in the preset scanning path direction in each image collection.

4. The system of claim 3, wherein, The at least two non-coherent line lights comprise a first line light and a second line light which are arranged in parallel; a first line light scanning region in a current region of interest overlaps with a second line light scanning region in a last continuous region of interest.

5. The system of any of claims 1-4, wherein, The number of the image collectors is more than two; the imaging module further comprises a second functional light splitting element which transmits or reflects the line light reflected by the to-be-detected object, separates the non-coherent line light with different characteristics and transmits the non-coherent line light to a corresponding image collector.

6. The system of claim 5, wherein, The light module further comprises a first lens and a first microscope objective; the first functional light splitting element, the first lens and the first microscope objective are sequentially arranged along an optical path; the non-coherent line light output by the first functional light splitting element enters the surface of the to-be-detected object after passing through the first lens and the first microscope objective.

7. The system of claim 5, wherein, The imaging module further comprises a second lens and a second microscopic objective, the second microscopic objective, the second lens and the second functional light splitting element are sequentially arranged along an optical path, the linear light reflected by the object to be measured is transmitted to the second functional light splitting element through the second microscopic objective and the second lens for transmission or reflection, and linear light with different characteristics is separated and transmitted to a corresponding image collector.

8. The system of claim 5, wherein, The first functional light splitting element is a dichroic mirror or a polarization light splitting element, and the second functional light splitting element is a dichroic mirror or a polarization light splitting element.

9. The system of claim 5, wherein, The illumination module further comprises an image collector, and the imaging module further comprises a light source; in the imaging module, the second functional light splitting element separates the illumination light emitted by the corresponding light source into linear light with different characteristics and transmits the linear light to the object to be measured. In the illumination module, the first functional light splitting element separates the linear light reflected by the object to be measured to obtain linear light with different characteristics and transmits the linear light to a corresponding image collector.

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