Line Spectrum Confocal Sensor

Abstract

The invention discloses a line spectrum confocal sensor, comprising: a light source, a light source optical fiber, a dispersion objective lens, a spectrometer, and a spectrometer optical fiber. The light source generates detection light, and the light source optical fiber converts the detection light into modulated detection light. The dispersion objective lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens, which are coaxially arranged in sequence from the dispersion objective lens object to the dispersion objective mirror image. The spectrometer optical fiber transfers the reflected light of the measured object to the spectrometer one by one. The spectrometer distinguishes the wavelength of the echo and generates images at different pixel positions on the camera. The dispersion objective lens in the invention is composed of eleven lenses and is designed as a double telecentric structure, which effectively ensures the consistency of the brightness and accuracy of the measurement light spot projected on the measured object, realizes dispersion under a coaxial optical path, and has the same optical path for emission and reception, a large measurement range, good angle adaptability, and a long working distance.

Description

Technical Field

[0001] The invention belongs to the field of optical measurement, and in particular relates to a line spectrum confocal sensor. Background Art

[0002] With the rapid development of precision and ultra-precision manufacturing industries, the demand for high-precision detection is increasing, so high-precision displacement sensors have also emerged. The accuracy of ultra-precision displacement sensors can reach the micron level; although traditional contact measurement also has high accuracy, it may scratch the surface of the object being measured, and when the object being measured is weakly rigid or light and soft materials, contact measurement will also cause elastic deformation, introducing measurement errors. In addition, contact measurement is slow and difficult to achieve automated measurement. Based on the many shortcomings of contact measurement, non-contact displacement sensors have received greater attention.

[0003] The spectral confocal displacement sensor can be used to accurately measure the size and displacement of the sample in a non-contact manner. The current surface contour and shape detector uses a spectral confocal displacement sensor. The sampling method of this technical solution is point measurement or line measurement. Point measurement has the defects of low sampling efficiency and slow working speed. Although line measurement can improve sampling efficiency, it also has problems such as small measurement range and poor angle adaptability.

[0004] In spectral confocal sensors, the dispersion lens is the core component, which determines the resolution, range, line length and other parameters. Existing line measurement spectral confocal sensors have problems such as small measurement range and poor angle adaptability in measuring the surface profile and shape of objects.

[0005] Specifically, the dispersion lens of the line measurement spectral confocal sensor used in the prior art has the following problems: first, the measurement range is small, which makes it difficult to meet the measurement requirements of products with a large measurement range; second, the angle adaptability is poor, and the reflection optical fiber collection ability is insufficient when measuring rough and complex surfaces, resulting in missing data points, which seriously affects the measurement accuracy; third, the working distance is too short, which makes it easy for interference to occur when measuring the interior or recessed areas of some products. Summary of the invention

[0006] The purpose of the present invention is to provide a line spectrum confocal sensor to solve the problems of small measurement range, poor angle adaptability and short working distance when the line spectrum confocal sensor in the prior art measures an object.

[0007] To achieve the above-mentioned object, the present invention provides a line spectrum confocal sensor, comprising: a light source, a light source optical fiber, a dispersion objective lens, a spectrometer, and a spectrometer optical fiber, wherein the light source is used to generate detection light;

[0008] The light source optical fiber is used to convert the detection light into modulated detection light, and the light source optical fiber includes a first light input end coupled with the light source and a first light output end coupled with the dispersion objective lens;

[0009] The dispersive objective lens is used to perform axial dispersion on the modulated detection light, and includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens, which are coaxially arranged in sequence from the object side of the dispersive objective lens to the image side of the dispersive objective lens;

[0010] The spectrometer optical fiber is used to transfer the reflected light of the measured object to the spectrometer in a one-to-one correspondence, and the spectrometer optical fiber includes a second light input end coupled to the dispersion objective lens and a second light output end coupled to the spectrometer;

[0011] The spectrometer is used to distinguish the wavelengths of the echoes and generate images at different pixel positions on the camera.

[0012] Preferably, the zoom ratio between the object side of the dispersive objective lens and the image side of the dispersive objective lens is 0.04 to 0.5.

[0013] Preferably, the first lens is used to eliminate the spherical aberration of the projected modulated detection light and produce partial dispersion; the second lens and the third lens are symmetrical structures, used to eliminate the field curvature and coma of the modulated detection light; the fourth lens and the fifth lens are used to balance the field curvature and coma of the modulated detection light; the sixth lens, the seventh lens, and the eighth lens are used to eliminate the spherical aberration and astigmatism of the projected modulated detection light; the ninth lens is used to control the optical focal length and produce a larger dispersion; the tenth lens and the eleventh lens are used to eliminate the residual coma and astigmatism of the modulated detection light.

[0014] Preferably, the first lens is a positive long focal length lens with a focal length ranging from 100mm to 200mm; the second lens is a positive long focal length lens with a focal length ranging from 80mm to 100mm; the third lens is a negative small focal length lens with a focal length ranging from -50mm to -40mm; the fourth lens is a positive small focal length lens with a focal length ranging from 70mm to 90mm; the fifth lens is a positive long focal length lens with a focal length ranging from 260mm to 300mm; the sixth lens is a positive long focal length lens with a focal length ranging from 1. The seventh lens is a positive long focal length lens, and the focal length ranges from 290mm to 300mm; the eighth lens is a positive long focal length lens, and the focal length ranges from 170mm to 190mm; the ninth lens is a negative long focal length lens, and the focal length ranges from -210mm to -230mm; the tenth lens is a positive long focal length lens, and the focal length ranges from 140mm to 150mm; the eleventh lens is a positive long focal length lens, and the focal length ranges from 80mm to 100mm.

[0015] Preferably, the first lens is a biconvex lens; the second lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the third lens is a biconcave lens; the fourth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the fifth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the sixth lens is a plano-convex lens, which is arranged toward the object side of the dispersive objective lens; the seventh lens is a plano-convex lens, which is arranged toward the object side of the dispersive objective lens; the eighth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the ninth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the tenth lens is a biconvex lens; and the eleventh lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens.

[0016] Preferably, the spectrometer comprises a first lens group, a dispersion component and a second lens group;

[0017] The first lens group is used to parallelize the reflected light of the object to be measured, and the dispersion component is used to disperse the parallelized reflected light;

[0018] The second lens group is used to focus the reflected light after dispersion and eliminate the chromatic aberration of the focused reflected light;

[0019] The object side of the spectrometer is the second light output end, and the image side of the spectrometer is the spectrum image collected by the camera.

[0020] Preferably, the zoom ratio of the spectrometer image space and the spectrometer object space ranges from 0.1 to 0.8.

[0021] Preferably, the first lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, and a sixteenth lens that are coaxially arranged;

[0022] The twelfth lens is used to balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light; the thirteenth lens is used to balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light again; the fourteenth lens is used to balance the distortion, astigmatism and field curvature of the re-compressed light beam to form a large field of view; the fifteenth lens and the sixteenth lens form a cemented structure to eliminate the chromatic aberration of the reflected light after field curvature, and cooperate with the fourteenth lens to form a large field of view and obtain the reflected light after dispersion;

[0023] The second lens group includes a seventeenth lens, an eighteenth lens, a nineteenth lens, a twentieth lens, a twenty-first lens, a twenty-second lens, a twenty-third lens, and a twenty-fourth lens that are coaxially arranged;

[0024] The seventeenth lens and the eighteenth lens are a glued structure, and are used to eliminate the chromatic aberration of the reflected light after the dispersion; the nineteenth lens is used to balance the coma, astigmatism and spherical aberration in the reflected light after the chromatic aberration is eliminated, so as to eliminate distortion; the twentieth lens is used to compensate for the spherical aberration and coma of the reflected light after the distortion is eliminated, so as to control the astigmatism, and compress the light beam divergence angle of the reflected light after the astigmatism is controlled; the twenty-first lens is used to compress the light beam divergence angle of the reflected light again, and eliminate astigmatism and distortion; the twenty-second lens, the twenty-third lens and the twenty-fourth lens are used to control the spherical aberration and coma of the reflected light, and further compress the light beam divergence angle of the reflected light.

[0025] Preferably, in the first lens group, the twelfth lens is a positive focal length lens, and the focal length ranges from 260mm to 280mm; the thirteenth lens is a positive focal length lens, and the focal length ranges from 80mm to 110mm; the fourteenth lens is a negative focal length lens, and the focal length ranges from -50mm to -30mm; the fifteenth lens and the sixteenth lens form a cemented lens, wherein the fifteenth lens is a negative focal length lens, and the focal length ranges from -160mm to -130mm; the sixteenth lens is a positive focal length lens, and the focal length ranges from 50mm to 70mm; in the second lens group, the seventeenth lens and the eighteenth lens form a cemented lens, wherein the seventeenth lens is a negative focal length lens, and the focal length ranges from 160mm to 130mm; The value range is -60mm to -40mm; the eighteenth lens is a positive focal length lens, and the focal length range is 100mm to 120mm; the nineteenth lens is a positive focal length lens, and the focal length range is 140mm to 170mm; the twentieth lens is a positive focal length lens, and the focal length range is 80mm to 110mm; the twenty-first lens is a positive focal length lens, and the focal length range is 130mm to 170mm; the twenty-second lens is a negative focal length lens, and the focal length range is -50mm to -30mm; the twenty-third lens is a positive focal length lens, and the focal length range is 80mm to 100mm; the twenty-fourth lens is a positive focal length lens, and the focal length range is 170mm to 220mm.

[0026] Preferably, in the first lens group, the twelfth lens is a plano-convex lens; the thirteenth lens is a biconvex lens; the fourteenth lens is a biconcave lens; the fifteenth lens is a meniscus lens, which is arranged toward the object side of the spectrometer; the sixteenth lens is a biconvex lens; the seventeenth lens is a biconcave lens; the eighteenth lens is a biconvex lens; the nineteenth lens is a biconvex lens; the twentieth lens is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-first lens is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-second lens is a plano-concave lens; the twenty-third lens is a plano-convex lens; and the twenty-fourth lens is a meniscus lens, which is arranged toward the object side of the spectrometer.

[0027] In a line spectrum confocal sensor shown in the present invention, a light source is used to emit detection light, and a light source optical fiber is used to modulate the detection light and generate hundreds of uniform point light sources. The multiple point light sources of the light source optical fiber (i.e., the first light output end) serve as the object side of a dispersive objective lens, and are scaled through the cooperation of the first lens to the eleventh lens of the dispersive objective lens to form a reduced line on the image plane. Since the dispersive objective lens uses a double telecentric optical path to generate dispersion, the object side telecentricity means that for the edge non-coaxial optical path, the main light is parallel to the optical axis like the axial light, thereby ensuring the brightness consistency between data points; the image side telecentricity makes the main light of the edge field of view parallel to the optical axis like the main light of the axial field of view, thereby ensuring that the axes of the cone angle of the light reaching the target point are parallel to each other, thereby ensuring The consistency of the brightness and accuracy of the measuring light spot projected onto the object to be measured is ensured; after the linear, dispersed, and uniform measuring light spot formed by the dispersive objective is projected onto the object to be measured, it is combined with a moving stage perpendicular to the line and parallel to the line to measure the object, and has a large measuring range, good angle adaptability, and a long working distance; the spectrometer optical fiber is used to transfer the reflected light of the object to be measured to the spectrometer one by one, and the spectrometer optical fiber includes a second light input end coupled to the dispersive objective lens and a second light output end coupled to the spectrometer. The spectrometer is used to distinguish the wavelength of the echo, generate images at different pixel positions on the camera, and calculate the height of the corresponding position of the target according to the wavelength, so as to realize high-precision three-dimensional scanning and model reconstruction of larger objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of an embodiment of a line spectrum confocal sensor of the present invention;

[0029] Figure 2 A schematic diagram of the optical path structure of an embodiment of a dispersive objective lens of the present invention;

[0030] Figure 3 A schematic diagram of the optical path structure of an embodiment of a spectrometer of the present invention;

[0031] in, Figure 1 In the figure, a light source 10, a light source optical fiber 20, a dispersion objective lens 30, a spectrometer optical fiber 40, a spectrometer 50, a first light input end 21, a first light output end 22, a second light input end 41, a second light output end 42, and a beam splitter 60;

[0032] Figure 2 , a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11;

[0033] Figure 3In the embodiment, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, the fifteenth lens L15, the sixteenth lens L16, the seventeenth lens L17, the eighteenth lens L18, the nineteenth lens L19, the twentieth lens L20, the twenty-first lens L21, the twenty-second lens L22, the twenty-third lens L23, the twenty-fourth lens L24, and the dispersion element 52. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not intended to limit the scope of protection of the present invention in any way.

[0035] Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items. In the drawings, the thickness, size and shape of the objects have been slightly exaggerated for ease of explanation. The drawings are only examples and are not drawn strictly to scale.

[0036] It should also be understood that the terms “comprises,” “including,” “having,” “includes,” and / or “comprising,” when used in this specification, indicate the presence of stated features, steps, integers, operations, elements, and / or parts, but do not exclude the presence or addition of one or more other features, steps, integers, operations, elements, parts, and / or combinations thereof.

[0037] As used in the specification, the terms "substantially," "approximately," and the like are intended to serve as terms of approximation rather than terms of degree, and are intended to account for the inherent deviations in measurements or calculations that would be recognized by those of ordinary skill in the art.

[0038] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0039] It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein may be combined with each other.

[0040] like Figure 1As shown, an embodiment provides a line spectrum confocal sensor, comprising: a light source 10, a light source optical fiber 20, a dispersive objective lens 30, a spectrometer optical fiber 40, and a spectrometer 50; the light source 10 is used to generate detection light; the light source optical fiber 20 comprises a first light input end 21 coupled to the light source and a first light output end 22 coupled to the dispersive objective lens 30, the light source optical fiber 20 is used to convert the detection light into modulated detection light; the dispersive objective lens 30 is used to perform axial dispersion on the modulated detection light.

[0041] like Figure 2 As shown, the dispersive objective lens 30 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10 and an eleventh lens L11 which are coaxially arranged in sequence from the object side of the dispersive objective lens to the image side of the dispersive objective lens. Among them, the first lens L1 is used to eliminate the spherical aberration of the projected modulated detection light and produce partial dispersion; the second lens L2 and the third lens L3 are symmetrical structures, which are used to eliminate the field curvature and coma of the modulated detection light; the fourth lens L4 and the fifth lens L5 are used to further balance the field curvature and coma of the modulated detection light; the sixth lens L6, the seventh lens L7, and the eighth lens L8 are used to further eliminate the spherical aberration and astigmatism of the projected modulated detection light; the ninth lens L9 is used to control the optical focal length and produce a larger dispersion; the tenth lens L10 and the eleventh lens L11 are used to eliminate the residual coma and astigmatism of the modulated detection light; the optical system composed of the first lens to the eleventh lens is designed as a double telecentric structure, which can effectively ensure the consistency of the brightness and accuracy of the measurement spot projected onto the object to be measured.

[0042] Among them, the object side of the dispersive objective lens is the optical fiber array of the first light output end 22, and the image side of the dispersive objective lens is the projected light spot of the line spectrum confocal sensor system; the spectrometer optical fiber 40 includes a second light input end 41 coupled to the dispersive objective lens 30 and a second light output end 42 coupled to the spectrometer 50. After the beam splitter 60 projects the reflected light of the object to be measured into the spectrometer optical fiber 40, the spectrometer optical fiber 40 is used to transfer the reflected light one by one to the spectrometer 50, and the spectrometer 50 is used to distinguish the wavelength of the echo and generate images at different pixel positions on the camera.

[0043] In this embodiment, the line spectrum confocal sensor is easy to commercialize, has high measurement accuracy, high environmental adaptability, simple structure, large measurement range, wide angle adaptability and long working distance, which greatly improves the adaptability of the line measurement spectrum confocal sensor to different measurement objects.

[0044] In a line spectrum confocal sensor shown in the present invention, the light source is used to emit detection light, the light source optical fiber 20 is used to modulate the detection light and generate hundreds of uniform point light sources, and the multiple point light sources of the light source optical fiber 20 (i.e., the first light output end 22) are used as the object side of the dispersive objective lens 30, and a reduced line is formed on the image plane through the dispersive objective lens 30. Since the dispersive objective lens 30 uses a double telecentric optical path to generate dispersion, the object side telecentricity is that for the edge non-coaxial optical path, the main light is parallel to the optical axis like the axial light, ensuring the brightness consistency between data points; the image side telecentricity makes the main light of the edge field of view and the main light of the axial field of view parallel to the optical axis, ensuring that the axes of the cone angle of the light reaching the target point are parallel to each other, thereby ensuring the consistency of the brightness and accuracy of the measurement spot projected on the object to be measured. After the linear, dispersed, and uniform measurement spot formed by the dispersive objective lens 30 is projected onto the object to be measured, it can achieve high-precision three-dimensional scanning and model reconstruction of larger objects in conjunction with a motion stage perpendicular to and parallel to the line. The modulated detection light is projected onto the object under test through the dispersive objective lens 30. The wavelengths of the focused light spots at different heights are different. The light returns through the dispersive objective lens 30 along the original optical path and is transmitted to the spectrometer through the spectrometer optical fiber 40 to form an image on the camera that can determine the wavelength of the echo. The height of the corresponding position of the object under test can be calculated based on the wavelength.

[0045] In the line spectrum confocal sensor, the light source types mainly include incandescent lamps, halogen lamps, fluorescent lamps, gas discharge lamps (such as mercury lamps, sodium lamps, xenon lamps), and LEDs. The brightness and life of the light source are the key considerations for selecting the light source of the line spectrum confocal sensor system. Brightness is a requirement for measuring surfaces with different reflectivity. When measuring objects with lower reflectivity, if the light source brightness is insufficient, the detector can only be used to extend the exposure time or increase the gain. This treatment will significantly reduce the detector's frame rate and signal-to-noise ratio; a short light source life will significantly increase the cost of light source replacement and equipment maintenance. In this embodiment, as a preferred solution, the light source is an LED light source, which takes into account brightness, stability, life, and spot uniformity, and has high coupling efficiency with the docking fiber and large transmitted light flux.

[0046] As mentioned above, in a line spectrum confocal sensor, the more optical fibers (optical channels) there are, the longer the line length projected by the system, and the higher the detection efficiency of the system. However, the more optical fibers there are, the larger the corresponding size of the optical device will be, and the corresponding optical design difficulty is too high. Therefore, in the existing line spectrum confocal sensor system, the length of the optical fiber array is usually not more than 20 mm. As a preferred solution, in a line spectrum confocal sensor shown in the present invention, based on the structural design of the dispersive objective lens 30, the length of the light source optical fiber 20 is set to 25 mm to 85 mm, and the zoom ratio of the object side of the dispersive objective lens 30 and the image side of the dispersive objective lens 30 is set between 0.04 and 0.5, so as to ensure the brightness and accuracy consistency of the light spot projected onto the object to be measured, while trying to increase the line length projected by the system. Of course, there is no doubt that in the line spectrum confocal sensor shown in the present invention, the optical fiber array can also be set to less than 25 mm, such as the conventional 20 mm.

[0047] After the detection light is modulated and split by the light source optical fiber 20, the modulated detection light formed by the multiple point light sources at the first light output end 22 of the light source optical fiber 20 reaches the dispersive objective lens 30, and the dispersive objective lens 30 disperses the modulated detection light, so that the modulated detection light forms an extended, linear, dispersed, and uniformly bright measurement light spot on the object to be measured.

[0048] In this embodiment, the dispersive objective lens 30 uses a combination of lenses with different curvatures, thicknesses and materials to control monochromatic aberrations on the basis of maximizing dispersion, including but not limited to spherical aberration, coma, field curvature, astigmatism, distortion and other aberrations, so that the system's dispersion spot at different wavelengths approaches or reaches the diffraction limit level, and has a perfect imaging effect for different wavelengths in the light source spectrum. The dispersive objective lens 30 does not use dispersive devices such as gratings, and realizes dispersion under the coaxial optical path, with the same optical path for transmission and reception.

[0049] The dispersion objective lens 30 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10 and an eleventh lens L11 which are coaxially arranged from the object side to the image side. The first lens to the third lens are used to eliminate the spherical aberration of the projected modulated detection light and generate partial dispersion; the second lens and the third lens are symmetrical structures, which are used to eliminate the field curvature and coma of the modulated detection light; the fourth lens and the fifth lens are used to further balance the field curvature and coma of the modulated detection light; the sixth lens, the seventh lens and the eighth lens are used to further eliminate the spherical aberration and astigmatism of the projected modulated detection light; the ninth lens is used to control the optical focal length and generate a large dispersion; the tenth lens and the eleventh lens are used to eliminate the residual coma and astigmatism of the modulated detection light; the optical system is designed as a double telecentric structure, which can effectively ensure the consistency of the brightness and accuracy of the measurement spot projected onto the object to be measured.

[0050] The dispersive objective lens in this embodiment is composed of a first lens L1 to an eleventh lens L11 to form an optical system. By using a combination of lenses with different focal lengths, thicknesses, and distances, monochromatic aberrations such as spherical aberration, coma, field curvature, astigmatism, distortion, etc. are controlled, and axial chromatic aberration is expanded at the same time, so that the dispersion spot of the system at different wavelengths is close to or reaches the diffraction limit level, and a perfect imaging effect is achieved for different wavelengths in the light source spectrum. The dispersive objective lens does not use dispersive devices such as gratings, and can achieve a larger line length at a closer distance, with higher working efficiency, and realizes dispersion under a coaxial optical path, with the same optical path for transmission and reception.

[0051] In one of the embodiments, as a preferred scheme, the first lens is a biconvex lens; the second lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the third lens is a biconcave lens; the fourth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the fifth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the sixth lens is a plano-convex lens, which is arranged toward the object side of the dispersive objective lens; the seventh lens is a plano-convex lens, which is arranged toward the object side of the dispersive objective lens; the eighth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the ninth lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the tenth lens is a biconvex lens; and the eleventh lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens.

[0052] In one of the embodiments, as a preferred scheme, the focal length of the first lens ranges from 100mm to 120mm; the focal length of the second lens ranges from 80mm to 100mm; the focal length of the third lens ranges from -50mm to -40mm; the focal length of the fourth lens ranges from 70mm to 90mm; the focal length of the fifth lens ranges from 260mm to 300mm; the focal length of the sixth lens ranges from 170mm to 180mm; the focal length of the seventh lens ranges from 290mm to 300mm; the focal length of the eighth lens ranges from 170mm to 190mm; the focal length of the ninth lens ranges from -210mm to -230mm; the focal length of the tenth lens ranges from 140mm to 150mm; and the focal length of the eleventh lens ranges from 80mm to 100mm.

[0053] In one embodiment, as a preferred scheme, the distance between the first lens and the second lens ranges from 30 mm to 60 mm; the distance between the second lens and the third lens ranges from 5 mm to 15 mm; the distance between the third lens and the fourth lens ranges from 2 mm to 10 mm; the distance between the fourth lens and the fifth lens ranges from 2 mm to 10 mm; the distance between the fifth lens and the sixth lens ranges from 20 mm to 50 mm; the distance between the sixth lens and the seventh lens ranges from 0.2 mm to 5 mm; the distance between the seventh lens and the eighth lens ranges from 0.2 mm to 5 mm; the distance between the eighth lens and the ninth lens ranges from 5 mm to 15 mm; the distance between the ninth lens and the tenth lens ranges from 10 mm to 30 mm; and the distance between the tenth lens and the eleventh lens ranges from 0.2 mm to 5 mm.

[0054] In one of the embodiments, as a preferred scheme, the center thickness of the first lens is in the range of 10mm-25mm; the center thickness of the second lens is in the range of 5mm-20mm; the center thickness of the third lens is in the range of 5mm-20mm; the center thickness of the fourth lens is in the range of 5mm-20mm; the center thickness of the fifth lens is in the range of 5mm-20mm; the center thickness of the sixth lens is in the range of 5mm-20mm; the center thickness of the seventh lens is in the range of 2mm-15mm; the center thickness of the eighth lens is in the range of 2mm-15mm; the center thickness of the ninth lens is in the range of 5mm-20mm; the center thickness of the tenth lens is in the range of 5mm-20mm; and the center thickness of the eleventh lens is in the range of 2mm-15mm.

[0055] The dispersive objective lens 30 is set up through a double telecentric structure to control the object telecentricity and image telecentricity respectively, which can be equivalent to a line light source in a large range, thereby generating a uniform dispersion of the line light source, ensuring the brightness and accuracy consistency of the measurement spot. At the same time, the dispersive objective lens 30 is set up in conjunction with the light source optical fiber 20, which also effectively improves the angular adaptability of the system. The angle size is related to the zoom factor β and the object numerical aperture NA1. The smaller the zoom factor β and the larger the object numerical aperture NA1, the larger the image numerical aperture NA2, that is, the better the angular adaptability.

[0056] In this embodiment, in the line spectrum confocal sensor, the zoom ratio of the dispersion objective lens 30 is between 0.04 and 0.5, and on this basis, the object side numerical aperture is increased as much as possible. Through the cooperation of the two, the system can achieve a large line length while ensuring that all points on the line are consistent in uniformity and accuracy. At the same time, a larger angle adaptability on the target surface is achieved, that is, the target can have light returning to the original optical fiber channel within the range of 90 degrees ± 35 degrees; taking into account the characteristics of large line length, high consistency and large angle.

[0057] In addition, the dispersion objective lens 30 all uses spherical lenses to generate chromatic aberration and correct other aberrations, which is convenient to process and simple to produce.

[0058] The reflected light reflected from the surface of the object to be measured is transmitted to the spectrometer 50 through the spectrometer optical fiber 40. The spectrometer 50 focuses the reflected light and quantifies the reflected light through a lens group arranged in the spectrometer. The quantized light wave generates a spectral peak on the spectrometer 50. The peak position of the spectral curve corresponds to the wavelength focused on the surface of the object to be measured for subsequent analysis.

[0059] In this embodiment, the length of the spectrometer optical fiber 40 is set to 25 mm to 85 mm, and its specific value is the same as that of the light source optical fiber 20. The reflected light on the object to be measured passes through the dispersive objective lens 30 and the beam splitter 60 to reach the spectrometer optical fiber 40. Due to the setting of the dispersive objective lens 30, the consistency of the light spot of the reflected light on the object to be measured projected into the optical fiber can also be effectively guaranteed.

[0060] As mentioned above, the consistency of the light spot projected by the spectrometer onto the camera affects the consistency of the optical channel at the non-central position. In order to effectively receive the light source projected by the large-sized spectrometer optical fiber 40 and ensure the consistency of the light spot projected by the spectrometer 50 onto the camera, in this embodiment, as a preferred scheme, the spectrometer 50 includes a first lens group, a dispersion component 52 and a second lens group, wherein the first lens group is used to collimate the reflected light to obtain parallel reflected light, and the dispersion component 52 is used to disperse the parallel reflected light; the second lens group is used to focus the dispersed reflected light and eliminate the chromatic aberration of the reflected light; wherein the object side of the spectrometer is the optical fiber array of the second light output end 42, and the image side of the spectrometer is the spectral image collected on the camera.

[0061] The structure of a general spectrometer is generally composed of a slit, a collimating component, a dispersing component, a focusing component, a camera, etc. The slit controls the input spot size, the optical system only corrects for on-axis aberrations, and the field of view is only on-axis. The line spectrum confocal spectrometer needs to collimate, disperse, focus, and measure the spectra of hundreds of channels at the same time, while ensuring the uniformity and accuracy of each channel.

[0062] In order to achieve consistency between each channel, the spectrometer of this embodiment adopts a double telecentric design: that is, the first lens group acts as a long-focal-length object-side telecentric, compressing the beam diameter to ensure the uniformity of each channel after collimation by the first lens group. At the same time, a symmetrical structure is adopted to more easily balance off-axis aberrations and increase the object-side field of view; the second lens group acts as a short-focal-length image-side telecentric, cooperating with the first lens group to form a scaling relationship, scaling the image to fit the detector size, and forming an appropriate focal length to focus the spectrum and fit the detector. The image-side telecentricity ensures the brightness consistency of each channel on the detector; starting from the light source, there are light homogenizers, double telecentric dispersive mirrors, double telecentric spectrometers, etc. to ensure the brightness consistency of the light channels on the final detector image plane.

[0063] As a preferred solution, the zoom ratio of the spectrometer image side and the spectrometer object side ranges from 0.1 to 0.8.

[0064] As a preferred solution, Figure 3 As shown, the first lens group includes a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, and a sixteenth lens L16 that are coaxially arranged; wherein the twelfth lens L12 is used to balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light; the thirteenth lens L13 is used to further balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light again; the fourteenth lens L14 is used to balance the distortion, astigmatism and field curvature of the re-compressed beam to form a large field of view; the fifteenth lens L15 and the sixteenth lens L16 form a cemented structure to eliminate the chromatic aberration of the reflected light after the field curvature, and cooperate with the fourteenth lens L14 to form a large field of view and obtain the radiated light after dispersion;

[0065] The second lens group is used for converging the reflected light after dispersion, and the second lens group includes a seventeenth lens L17, an eighteenth lens L18, a nineteenth lens L19, a twentieth lens L20, a twenty-first lens L21, a twenty-second lens L22, a twenty-third lens L23, and a twenty-fourth lens L24 which are coaxially arranged; the seventeenth lens L17 and the eighteenth lens L18 are a cemented structure for eliminating the chromatic aberration of the reflected light after the chromatic aberration is eliminated; the nineteenth lens L19 is used for balancing the coma aberration, astigmatism and spherical aberration in the reflected light after the chromatic aberration is eliminated, and eliminating the distortion; the twentieth lens L20 is used for compensating the spherical aberration and coma aberration of the reflected light after the distortion is eliminated, controlling the astigmatism, and compressing the beam divergence angle of the reflected light after the astigmatism is controlled; the twenty-first lens L21 is used for further compressing the beam divergence angle of the reflected light, and eliminating the astigmatism and distortion; the twenty-second lens L22, the twenty-third lens L23, and the twenty-fourth lens L24 are used for controlling the spherical aberration and coma aberration of the reflected light, and further compressing the beam divergence angle of the reflected light.

[0066] In the first lens group, the twelfth lens L12 is a positive focal length lens, and the focal length ranges from 260mm to 280mm; the thirteenth lens L13 is a positive focal length lens, and the focal length ranges from 80mm to 110mm; the fourteenth lens L14 is a negative focal length lens, and the focal length ranges from -50mm to -30mm; the fifteenth lens L15 and the sixteenth lens L16 form a cemented lens, wherein the fifteenth lens L15 is a negative focal length lens, and the focal length ranges from -160mm to -130mm; the sixteenth lens L16 is a positive focal length lens, and the focal length ranges from 50mm to 70mm; in the second lens group, the seventeenth lens L17 and the eighteenth lens L18 form a cemented lens, wherein the seventeenth lens L17 is a negative focal length lens, The focal length ranges from -60mm to -40mm; the eighteenth lens L18 is a positive focal length lens, and the focal length ranges from 100mm to 120mm; the nineteenth lens L19 is a positive focal length lens, and the focal length ranges from 140mm to 170mm; the twentieth lens L20 is a positive focal length lens, and the focal length ranges from 80mm to 110mm; the twenty-first lens L21 is a positive focal length lens, and the focal length ranges from 130mm to 170mm; the twenty-second lens L22 is a negative focal length lens, and the focal length ranges from -50mm to -30mm; the twenty-third lens L23 is a positive focal length lens, and the focal length ranges from 80mm to 100mm; and the twenty-fourth lens L24 is a positive focal length lens, and the focal length ranges from 170mm to 220mm.

[0067] In the first lens group, the twelfth lens L12 is a plano-convex lens; the thirteenth lens L13 is a biconvex lens; the fourteenth lens L14 is a biconcave lens; the fifteenth lens L15 is a meniscus lens, which is arranged toward the object side of the spectrometer; the sixteenth lens L16 is a biconvex lens; the seventeenth lens L17 is a biconcave lens; the eighteenth lens L18 is a biconvex lens; the nineteenth lens L19 is a biconvex lens; the twentieth lens L20 is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-first lens L21 is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-second lens L22 is a plano-concave lens; the twenty-third lens L23 is a plano-convex lens; and the twenty-fourth lens L24 is a meniscus lens, which is arranged toward the object side of the spectrometer.

[0068] The reflected light composed of multiple point light sources is collimated by the first lens group to form parallel light that is incident on the dispersion component 52. The dispersion component 52 is used to disperse the parallel light. In this embodiment, the dispersion component 52 is a reflective grating or a transmissive grating to disperse the reflected light after collimation by the first lens group. The dispersed reflected light is incident on the second lens group.

[0069] In addition, the spectral confocal sensor shown in the present invention also takes into account the matching problem of the spectral consistency of the light source optical fiber 20, the dispersive objective lens 30, the spectrometer optical fiber 40, and the spectrometer 50; the light source optical fiber 20 and the spectrometer optical fiber 40 have optimal light transmission wavelengths due to material limitations, the dispersive objective lens 30 has a design wavelength, and the dispersive device in the spectrometer 50 also has requirements for adapting to wavelengths. In this embodiment, the working bands of the four are set to the same so that they can be used collaboratively.

[0070] The key to this embodiment lies in the lens design, and the most important thing is the combination of curvature, thickness and material, which not only meets the requirements of a large range but also realizes wide-angle adaptability and has a long working distance. Glass combinations with different curvatures, thicknesses and materials are used to control monochromatic aberrations on the basis of maximizing dispersion as much as possible, including but not limited to spherical aberration, coma, field curvature, astigmatism, distortion and other aberrations; the system's diffuse spots at different wavelengths are made close to or reach the diffraction limit level, and perfect imaging effects are achieved for different wavelengths in the light source. No dispersive devices such as gratings are used, and dispersion under a coaxial optical path is realized, with the emission and reception on the same optical path.

[0071] The serial numbers of the embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A line spectrum confocal sensor, comprising: A light source, a light source optical fiber, a dispersive objective lens, a spectrometer, and a spectrometer optical fiber, characterized in that: The light source is used to generate detection light; The light source optical fiber is used to convert the detection light into modulated detection light, and the light source optical fiber includes a first light input end coupled with the light source and a first light output end coupled with the dispersion objective lens; The dispersive objective lens is used to perform axial dispersion on the modulated detection light, and includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens, which are coaxially arranged in sequence from the object side of the dispersive objective lens to the image side of the dispersive objective lens; The spectrometer optical fiber is used to transfer the reflected light of the measured object to the spectrometer in a one-to-one correspondence, and the spectrometer optical fiber includes a second light input end coupled to the dispersion objective lens and a second light output end coupled to the spectrometer; The spectrometer is used to distinguish the wavelengths of the echoes and generate images at different pixel positions on the camera; The first lens is used to eliminate the spherical aberration of the projected modulated detection light and generate partial dispersion; the second lens and the third lens are symmetrical structures, and are used to eliminate the field curvature and coma of the modulated detection light; the fourth lens and the fifth lens are used to balance the field curvature and coma of the modulated detection light; the sixth lens, the seventh lens, and the eighth lens are used to eliminate the spherical aberration and astigmatism of the projected modulated detection light; the ninth lens is used to control the optical power and generate a larger dispersion; the tenth lens and the eleventh lens are used to eliminate the residual coma and astigmatism of the modulated detection light; The first lens is a positive long focal length lens with a focal length ranging from 100mm to 200mm; the second lens is a positive long focal length lens with a focal length ranging from 80mm to 100mm; the third lens is a negative small focal length lens with a focal length ranging from -50mm to -40mm; the fourth lens is a positive small focal length lens with a focal length ranging from 70mm to 90mm; the fifth lens is a positive long focal length lens with a focal length ranging from 260mm to 300mm; the sixth lens is a positive long focal length lens with a focal length ranging from The seventh lens is a positive long focal length lens, and the focal length ranges from 290mm to 300mm; the eighth lens is a positive long focal length lens, and the focal length ranges from 170mm to 190mm; the ninth lens is a negative long focal length lens, and the focal length ranges from -210mm to -230mm; the tenth lens is a positive long focal length lens, and the focal length ranges from 140mm to 150mm; the eleventh lens is a positive long focal length lens, and the focal length ranges from 80mm to 100mm.

2. The line spectrum confocal sensor according to claim 1, characterized in that: The zoom ratio between the object side of the dispersive objective lens and the image side of the dispersive objective lens is 0.04 to 0.

5.

3. The line spectrum confocal sensor according to claim 1, characterized in that: The first lens is a biconvex lens; the second lens is a meniscus lens, which is arranged toward the object side of the dispersive objective lens; the third lens is a biconcave lens; the fourth lens is a meniscus lens, which is arranged toward the dispersive objective lens; the fifth lens is a meniscus lens, which is arranged toward the dispersive objective lens; the sixth lens is a plano-convex lens, which is arranged toward the dispersive objective lens; the seventh lens is a plano-convex lens, which is arranged toward the object side of the dispersive objective lens; The eighth lens is a meniscus lens, which is arranged toward the object side of the dispersion objective lens; the ninth lens is a meniscus lens, which is arranged toward the image side of the dispersion objective lens; The tenth lens is a biconvex lens; the eleventh lens is a meniscus lens, which is arranged toward the object side of the dispersion objective lens.

4. The line spectrum confocal sensor according to claim 1, characterized in that: The spectrometer includes a first lens group, a dispersion component and a second lens group; The first lens group is used to parallelize the reflected light of the object to be measured, and the dispersion component is used to disperse the parallelized reflected light; The second lens group is used to focus the reflected light after dispersion and eliminate the chromatic aberration of the focused reflected light; The object side of the spectrometer is the second light output end, and the image side of the spectrometer is the spectrum image collected by the camera.

5. The line spectrum confocal sensor according to claim 4, characterized in that: The zoom ratio of the spectrometer image side and the spectrometer object side ranges from 0.1 to 0.

8.

6. The line spectrum confocal sensor according to claim 4, characterized in that: The first lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, and a sixteenth lens that are coaxially arranged; The twelfth lens is used to balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light; the thirteenth lens is used to balance the spherical aberration of the reflected light and compress the beam diameter of the reflected light again; the fourteenth lens is used to balance the distortion, astigmatism and field curvature of the re-compressed light beam to form a large field of view; the fifteenth lens and the sixteenth lens form a cemented structure to eliminate the chromatic aberration of the reflected light after field curvature, and cooperate with the fourteenth lens to form a large field of view and obtain the reflected light after dispersion; The second lens group includes a seventeenth lens, an eighteenth lens, a nineteenth lens, a twentieth lens, a twenty-first lens, a twenty-second lens, a twenty-third lens, and a twenty-fourth lens that are coaxially arranged; The seventeenth lens and the eighteenth lens are a glued structure, and are used to eliminate the chromatic aberration of the reflected light after the dispersion; the nineteenth lens is used to balance the coma, astigmatism and spherical aberration in the reflected light after the chromatic aberration is eliminated, so as to eliminate distortion; the twentieth lens is used to compensate for the spherical aberration and coma of the reflected light after the distortion is eliminated, so as to control the astigmatism, and compress the light beam divergence angle of the reflected light after the astigmatism is controlled; the twenty-first lens is used to compress the light beam divergence angle of the reflected light again, and eliminate astigmatism and distortion; the twenty-second lens, the twenty-third lens and the twenty-fourth lens are used to control the spherical aberration and coma of the reflected light, and further compress the light beam divergence angle of the reflected light.

7. The line spectrum confocal sensor according to claim 6, characterized in that: In the first lens group, the twelfth lens is a positive focal length lens, and the focal length ranges from 260mm to 280mm; the thirteenth lens is a positive focal length lens, and the focal length ranges from 80mm to 110mm; the fourteenth lens is a negative focal length lens, and the focal length ranges from -50mm to -30mm; the fifteenth lens and the sixteenth lens form a cemented lens, wherein the fifteenth lens is a negative focal length lens, and the focal length ranges from -160mm to -130mm; the sixteenth lens is a positive focal length lens, and the focal length ranges from 50mm to 70mm; in the second lens group, the seventeenth lens and the eighteenth lens form a cemented lens, wherein the seventeenth lens is a negative focal length lens, and the focal length ranges from The eighteenth lens is a positive focal length lens, and the focal length ranges from 100mm to 120mm; the nineteenth lens is a positive focal length lens, and the focal length ranges from 140mm to 170mm; the twentieth lens is a positive focal length lens, and the focal length ranges from 80mm to 110mm; the twenty-first lens is a positive focal length lens, and the focal length ranges from 130mm to 170mm; the twenty-second lens is a negative focal length lens, and the focal length ranges from -50mm to -30mm; the twenty-third lens is a positive focal length lens, and the focal length ranges from 80mm to 100mm; the twenty-fourth lens is a positive focal length lens, and the focal length ranges from 170mm to 220mm.

8. The line spectrum confocal sensor according to claim 7, characterized in that: In the first lens group, the twelfth lens is a plano-convex lens; the thirteenth lens is a biconvex lens; the fourteenth lens is a biconcave lens; the fifteenth lens is a meniscus lens, which is arranged toward the object side of the spectrometer; and the sixteenth lens is a biconvex lens; The seventeenth lens is a biconcave lens; the eighteenth lens is a biconvex lens; the nineteenth lens is a biconvex lens; the twentieth lens is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-first lens is a meniscus lens, which is arranged toward the object side of the spectrometer; the twenty-second lens is a plano-concave lens; the twenty-third lens is a plano-convex lens; and the twenty-fourth lens is a meniscus lens, which is arranged toward the object side of the spectrometer.

Images