Disclosure of Invention
The invention aims 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.
To achieve the above object, the present invention provides a line-spectrum confocal sensor, including: the device comprises 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 for generating detection light;
the light source optical fiber is used for converting the detection light into modulation detection light and comprises a first light inlet end coupled with the light source and a first light outlet end coupled with the dispersion objective lens;
the dispersive objective lens is used for carrying out axial dispersion on the modulated detection light and 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 object space of the dispersive objective lens to the image space of the dispersive objective lens;
the spectrometer optical fiber is used for transferring the reflected light of the measured object to the spectrometer in a one-to-one correspondence manner, and comprises a second light inlet end coupled with the dispersion objective lens and a second light outlet end coupled with the spectrometer;
the spectrometer is used for distinguishing the wavelength of the echo and generating images at different pixel positions on the camera.
Preferably, the zoom magnification between the object side of the dispersive objective and the image side of the dispersive objective is 0.04 to 0.5.
Preferably, the first lens is used for eliminating spherical aberration of the projection modulation detection light and generating partial dispersion; the second lens and the third lens are of symmetrical structures and are used for eliminating field curvature and coma aberration of the modulation detection light; the fourth lens and the fifth lens are used for balancing field curvature and coma of the modulated detection light; the sixth lens, the seventh lens and the eighth lens are used for eliminating spherical aberration and astigmatism of the projection modulation detection light; the ninth lens is used for controlling the focal power and generating larger dispersion; the tenth lens and the eleventh lens are used for eliminating modulation detection light residual coma aberration and astigmatism.
Preferably, the first lens is a positive long focal length lens, and the focal length value range is 100mm to 200 mm; the second lens is a positive long focal length lens, and the focal length value range is 80mm to 100 mm; the third lens is a negative small focal length lens, and the focal length value range is-50 mm to-40 mm; the fourth lens is a positive small-focal-length lens, and the focal length value range is 70mm to 90 mm; the fifth lens is a positive long focal length lens, and the focal length value range is 260mm to 300 mm; the sixth lens is a positive long focal length lens, and the focal length value range is 170mm to 180 mm; the seventh lens is a positive long focal length lens, and the focal length value range is 290-300 mm; the eighth lens is a positive long-focus lens, and the focus value range is 170mm to 190 mm; the ninth lens is a negative long-focus lens, and the focus value range is-210 mm to-230 mm; the tenth lens is a positive long-focus lens, and the focus value range is 140mm to 150 mm; the eleventh lens is a positive long focal length lens, and the focal length ranges from 80mm to 100 mm.
Preferably, the first lens is a biconvex lens; the second lens is a meniscus lens and is arranged towards the object space of the dispersive objective lens; the third lens is a biconcave lens; the fourth lens is a meniscus lens and is arranged towards the image space of the dispersive objective lens; the fifth lens is a meniscus lens, the sixth lens is a plano-convex lens arranged towards the image space of the dispersion objective lens and is arranged towards the image space of the dispersion objective lens; the seventh lens is a plano-convex lens and is arranged towards the object space of the dispersive objective lens; the eighth lens is a meniscus lens and is arranged towards the object space of the dispersive objective lens; the ninth lens is a meniscus lens and is arranged towards the image space of the dispersive objective lens; the tenth lens is a biconvex lens; the eleventh lens is a meniscus lens and is arranged towards the object side of the dispersive objective lens.
Preferably, the spectrometer comprises a first lens group, a dispersive component and a second lens group;
the first lens group is used for paralleling the reflected light of the measured object, and the dispersion assembly is used for dispersing the paralleled reflected light;
the second lens group is used for focusing the reflected light after dispersion and eliminating chromatic aberration of the focused reflected light;
the object space of the spectrograph is the second light-emitting end, and the image space of the spectrograph is a spectral image collected by the camera.
Preferably, the zoom ratio of the image space and the object space of the spectrometer ranges from 0.1 to 0.8.
Preferably, the first lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, a sixteenth lens, which are coaxially disposed;
the twelfth lens is used for balancing spherical aberration of the reflected light and compressing the beam diameter of the reflected light; the thirteenth lens is used for balancing the spherical aberration of the reflected light and compressing the beam diameter of the reflected light again; the fourteenth lens is used for balancing distortion, astigmatism and field curvature of the recompressed beam to form a large field of view; the fifteenth lens and the sixteenth lens form a gluing structure which is used for eliminating chromatic aberration of reflected light after field curvature and matched with the fourteenth lens to form a large field of view so as to obtain the reflected light after chromatic dispersion;
the second lens group comprises 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 which are coaxially arranged;
the seventeenth lens and the eighteenth lens are of a glued structure and are used for eliminating reflected light chromatic aberration after chromatic dispersion; the nineteenth lens is used for balancing coma aberration, astigmatism and spherical aberration in the reflected light after chromatic aberration is eliminated so as to eliminate distortion; the twentieth lens is used for compensating the spherical aberration and the coma aberration of the reflected light after the distortion is eliminated so as to control the astigmatism, and compressing and controlling the beam divergence angle of the reflected light after the astigmatism; the twenty-first lens is used for compressing the beam divergence angle of the reflected light again and eliminating astigmatism and distortion; the twenty-second lens, the twenty-third lens and the twenty-fourth lens are used for controlling spherical aberration and coma aberration of reflected light and further compressing a beam divergence angle of the reflected light.
Preferably, in the first lens group, the twelfth lens is a positive focal length lens, and the focal length ranges from 260mm to 280 mm; the thirteenth lens is a positive focal length lens, and the focal length value range is 80mm to 110 mm; the fourteenth lens is a negative focal length lens, and the focal length ranges from minus 50mm to minus 30 mm; 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 range is-160 mm to-130 mm; the sixteenth lens is a positive focal length lens, and the focal length value range is 50mm to 70 mm; in the second lens group, a seventeenth lens and the eighteenth lens form a cemented lens, wherein the seventeenth lens is a negative focal length lens, and the focal length range is-60 mm to-40 mm; the eighteenth lens is a positive focal length lens, and the focal length value range is 100mm to 120 mm; the nineteenth lens is a positive focal length lens, and the focal length value range is 140mm to 170 mm; the twentieth lens is a positive focal length lens, and the focal length is 80mm to 110 mm; the twenty-first lens is a positive focal length lens, and the focal length value range is 130mm to 170 mm; the twenty-second lens is a negative focal length lens, and the focal length range is-50 mm to-30 mm; the twenty-third lens is a positive focal length lens, and the focal length value range is 80mm to 100 mm; the twenty-fourth lens is a positive focal length lens, and the focal length value range is 170mm to 220 mm.
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 and is arranged towards the object space of the spectrograph; the sixteenth lens is a biconvex lens; the seventeenth lens is a biconcave lens; the eighteenth lens is a biconvex lens; the nineteenth lens element is a biconvex lens element; the twentieth lens is a meniscus lens and is arranged towards the object space of the spectrograph; the twenty-first lens is a meniscus lens and is arranged towards the object space of the spectrograph; the twenty-second lens is a plano-concave lens; the twenty-third lens is a plano-convex lens; the twenty-fourth lens is a meniscus lens and is arranged towards the object space of the spectrometer.
In the line spectrum confocal sensor, a light source is used for emitting detection light, a light source optical fiber is used for modulating the detection light and generating hundreds of uniform point light sources, a plurality of point light sources (namely, a first light outlet end) of the light source optical fiber are used as an object space of a dispersion objective lens, zooming is realized through matching of a first lens to an eleventh lens of the dispersion objective lens, and a reduced line is formed on an image surface; the image space telecentricity enables the chief ray of the marginal field of view to be parallel to the optical axis as well as the chief ray of the on-axis field of view, so that the axes of the cone angles of the light reaching the target point are ensured to be parallel to each other, and the consistency of the brightness and the precision of the measuring light spot projected onto the measured object is ensured; after linear, dispersed and uniform measuring light spots formed by the dispersive objective lens are projected on a measured object, the linear, dispersed and uniform measuring light spots are matched with a moving platform which is perpendicular to a line and parallel to the line, and when the object is measured, the measuring range is large, the angle adaptability is good, and the working distance is long; the spectrometer optical fiber is used for transferring reflected light of a measured object to the spectrometer in a one-to-one correspondence mode, the spectrometer optical fiber comprises a second light inlet end coupled with the dispersion objective lens and a second light outlet end coupled with the spectrometer, the spectrometer is used for distinguishing the wavelength of an echo, images are generated at different pixel positions on the camera, the height of a target corresponding position is calculated according to the wavelength, and high-precision three-dimensional scanning and model reconstruction of a large object can be achieved.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention in any way.
Like reference numerals refer to like elements throughout the specification. 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 an object have been slightly exaggerated for convenience of explanation. The figures are purely diagrammatic and not drawn to scale.
It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, integers, operations, elements, components, and/or groups thereof.
The terms "substantially", "about" and the like as used in the specification are used as terms of approximation and not as terms of degree, and are intended to account for inherent deviations in measured or calculated values that would be recognized by one of ordinary skill in the art.
Unless otherwise defined, all terms (including 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. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
As shown in fig. 1, an embodiment provides a line-spectrum confocal sensor, including: a light source 10, a light source optical fiber 20, a dispersion objective lens 30, a spectrometer optical fiber 40 and a spectrometer 50; the light source 10 is used for generating detection light; the light source fiber 20 comprises a first light inlet end 21 coupled with the light source and a first light outlet end 22 coupled with the dispersive objective lens 30, and the light source fiber 20 is used for converting the detection light into modulated detection light; the dispersive objective lens 30 is used for axially dispersing the modulated detection light.
As shown in fig. 2, the 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 disposed in order from the objective side of the objective lens to the image side of the objective lens. The first lens L1 is used for eliminating the spherical aberration of the projection modulation detection light and generating partial dispersion; the second lens L2 and the third lens L3 are symmetrical structures, and are used for eliminating field curvature and coma aberration of the modulated detection light; the fourth lens L4 and the fifth lens L5 are used to further balance the field curvature and the coma aberration of the modulated detection light; the sixth lens L6, the seventh lens L7, and the eighth lens L8 are used to further eliminate spherical aberration and astigmatism of the projection modulation detection light; the ninth lens L9 is used to control the optical power and produce large dispersion; the tenth lens L10 and the eleventh lens L11 are used for eliminating residual coma and astigmatism of the modulated detection light; the optical system formed by the first lens to the 11 th lens is designed into a double telecentric structure, so that the consistency of the brightness and the precision of a measuring light spot projected onto a measured object can be effectively ensured.
The object space of the dispersion objective is the optical fiber array of the first light-emitting end 22, and the image space of the dispersion objective is the light spot projected by the line spectrum confocal sensor system; the spectrometer optical fiber 40 comprises a second light inlet end 41 coupled with the dispersion objective lens 30 and a second light outlet end 42 coupled with the spectrometer 50, the spectroscope 60 projects reflected light of a measured object to be transferred to the spectrometer optical fiber 40, the spectrometer optical fiber 40 is used for transferring the reflected light to the spectrometer 50 in a one-to-one correspondence manner, the spectrometer 50 is used for distinguishing the wavelength of an echo, and images are generated at different pixel positions on a camera.
In the embodiment, the line spectrum confocal sensor is easy to produce, high in measurement precision, high in environmental adaptability and simple in structure, has a large measurement range, large-angle adaptability and a long working distance, and greatly improves the adaptability of the line spectrum confocal sensor to different measurement objects.
In the line spectrum confocal sensor shown in the invention, a light source is used for emitting and generating detection light, a light source optical fiber 20 is used for modulating the detection light and generating hundreds of uniform point light sources, a plurality of point light sources (namely, a first light outlet end 22) of the light source optical fiber 20 are used as an object space of a dispersion objective lens 30, and a reduced line is formed on an image surface through the dispersion objective lens 30; the image space telecentricity enables the chief ray of the marginal field of view to be parallel to the optical axis as well as the chief ray of the on-axis field of view, and ensures that the axes of the cone angles of the light reaching the target point are parallel to each other, thereby ensuring the consistency of the brightness and the precision of the measuring light spot projected on the measured object. After the linear, dispersed and uniform measurement light spots formed by the dispersive objective lens 30 are projected on a measured object, the linear, dispersed and uniform measurement light spots can be matched with a motion platform which is perpendicular to the line and parallel to the line, and high-precision three-dimensional scanning and model reconstruction of a large object can be realized. The modulated detection light is projected to a measured object through the dispersion objective lens 30, the light wavelengths of the focusing light spots at different heights are different, the modulated detection light returns through the dispersion objective lens 30 according to the original light path and is transmitted to the spectrometer through the spectrometer optical fiber 40, so that an image capable of judging the wavelength of the echo is formed on the camera, and the height of the corresponding position of the measured object can be calculated according to the wavelength.
In the line spectrum confocal sensor, the light source type mainly includes incandescent lamp, halogen lamp, fluorescent lamp, gas discharge lamp (such as mercury lamp, sodium lamp, xenon lamp), LED, wherein the light source brightness and light source life are the key consideration factors of the light source selection of the line spectrum confocal sensor system, the brightness is the requirement for measuring the surfaces with different reflectivity, when measuring the object to be measured with lower reflectivity, if the light source brightness is insufficient, the exposure time can only be prolonged or the gain can be improved by the detector, and the processing can obviously reduce the frame rate and the signal-to-noise ratio of the detector; short light source life can significantly increase light source replacement and equipment maintenance costs. In this embodiment, as a preferred scheme, the light source is an LED light source, which gives consideration to brightness, stability, lifetime, and uniformity of light spots, and the butt optical fiber has high coupling efficiency and large transmission luminous flux.
As mentioned above, in the line spectrum confocal sensor, the larger the number of optical fibers (optical channels), the longer the line length projected by the system, and the higher the detection efficiency of the system, but the larger the number of optical fibers, the larger the corresponding size of the optical device, and the higher the difficulty of the corresponding optical design, so that in the existing line spectrum confocal sensor system, the length of the optical fiber array is usually not greater than 20 mm. In a preferred embodiment, in the 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 fiber 20 is set to be 25mm to 85mm, and the zoom ratio between the object space of the dispersive objective lens 30 and the image space of the dispersive objective lens 30 is set to be 0.04 to 0.5, so as to improve the length of the line projected by the system as much as possible while ensuring the uniformity of the brightness and accuracy of the light spot projected to the object to be measured. Of course, it is needless to say that in the line spectral confocal sensor shown in the present invention, the optical fiber array may be set to be 25mm or less, such as 20mm as is conventional.
After the detection light is modulated and split by the light source fiber 20, the modulated detection light formed by the plurality of point light sources at the first light outlet end 22 of the light source fiber 20 reaches the dispersion objective lens 30, and the dispersion objective lens 30 disperses the modulated detection light, so that the modulated detection light forms an extended, linear, dispersed and uniform-brightness measurement light spot in one direction on the measured object and is projected on the measured object.
In this embodiment, the objective lens 30 uses lens combinations with different curvatures, thicknesses and materials to control monochromatic aberrations including aberrations such as spherical aberration, coma, field curvature, astigmatism and distortion on the basis of maximizing chromatic dispersion, so that the system has a diffuse spot close to or reaching a diffraction limit level at different wavelengths, and has perfect imaging effect on different wavelengths in a light source spectrum, and the objective lens 30 does not use dispersive devices such as gratings, thereby realizing chromatic dispersion under a coaxial light path, and transmitting and receiving the same light path.
The objective lens 30 includes, in order from the object side to the image side, 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 disposed. The first lens is used for eliminating spherical aberration of the projection modulation detection light and generating partial dispersion; the second lens and the third lens are of symmetrical structures and are used for eliminating field curvature and coma aberration of the modulation detection light; the fourth lens and the fifth lens are used for further balancing field curvature and coma of the modulated detection light; the sixth lens, the seventh lens and the eighth lens are used for further eliminating spherical aberration and astigmatism of the projection modulation detection light; the ninth lens is used for controlling the focal power and generating larger dispersion; the tenth lens and the eleventh lens are used for eliminating the residual coma aberration and astigmatism of the modulated detection light; the optical system is designed to be a double telecentric structure, so that the consistency of the brightness and the precision of the measuring light spot projected onto the measured object can be effectively ensured.
The dispersive objective lens in this embodiment is composed of an optical system of a first lens L1 to an eleventh lens L11, and monochromatic aberration is controlled by using lens combinations of different focal lengths, thicknesses, and distances: the system has the advantages that spherical aberration, coma, field curvature, astigmatism, distortion and other aberrations are simultaneously expanded, axial chromatic aberration is simultaneously expanded, so that the diffuse spot of the system under different wavelengths approaches or reaches the diffraction limit level, perfect imaging effects are achieved for different wavelengths in a light source spectrum, and the dispersion objective lens does not use a grating and other dispersion devices, so that a larger line length is realized in a shorter distance, higher working efficiency is achieved, and dispersion, emission and reception under a coaxial light path are realized.
In one embodiment, as a preferable solution, the first lens is a biconvex lens; the second lens is a meniscus lens and is arranged towards the object space of the dispersive objective lens; the third lens is a biconcave lens; the fourth lens is a meniscus lens and is arranged towards the image space of the dispersive objective lens; the fifth lens is a meniscus lens and is arranged towards the image space of the dispersive objective lens; the sixth lens is a plano-convex lens and is arranged towards the image space of the dispersive objective lens; the seventh lens is a plano-convex lens and is arranged towards the object space of the dispersive objective lens; the eighth lens is a meniscus lens and is arranged towards the object space of the dispersive objective lens; the ninth lens is a meniscus lens and is arranged towards the image space of the dispersive objective lens; the tenth lens is a biconvex lens; the eleventh lens is a meniscus lens and is arranged towards the object side of the dispersive objective lens.
In one embodiment, as a preferable scheme, a focal length of the first lens ranges from 100mm to 120 mm; the focal length range of the second lens is 80mm to 100 mm; the focal length of the third lens ranges from minus 50mm to minus 40 mm; the focal length of the fourth lens ranges from 70mm to 90 mm; the focal length range of the fifth lens is 260mm to 300 mm; the focal length range of the sixth lens is 170mm to 180 mm; the focal length range of the seventh lens is 290mm to 300 mm; the focal length range of the eighth lens is 170mm to 190 mm; the focal length of the ninth lens ranges from-210 mm to-230 mm; the focal length of the tenth lens ranges from 140mm to 150 mm; the focal length of the eleventh lens ranges from 80mm to 100 mm.
In one embodiment, as a preferable scheme, a distance between the first lens and the second lens ranges from 30mm to 60 mm; the range of the distance between the second lens and the third lens is 5mm to 15 mm; the distance between the third lens and the fourth lens ranges from 2mm to 10 mm; the distance between the fourth lens and the fifth lens ranges from 2mm to 10 mm; the distance between the fifth lens and the sixth lens ranges from 20mm to 50 mm; the distance between the sixth lens and the seventh lens ranges from 0.2mm to 5 mm; the distance between the seventh lens and the eighth lens ranges from 0.2mm to 5 mm; the range of the distance between the eighth lens and the ninth lens is 5mm to 15 mm; the distance between the ninth lens and the tenth lens ranges from 10mm to 30 mm; the spacing between the tenth lens and the eleventh lens ranges from 0.2mm to 5 mm.
In one embodiment, as a preferable scheme, the central thickness of the first lens ranges from 10mm to 25 mm; the central thickness of the second lens ranges from 5mm to 20 mm; the central thickness of the third lens ranges from 5mm to 20 mm; the central thickness of the fourth lens ranges from 5mm to 20 mm; the central thickness of the fifth lens ranges from 5mm to 20 mm; the central thickness of the sixth lens ranges from 5mm to 20 mm; the central thickness of the seventh lens ranges from 2mm to 15 mm; the value range of the central thickness of the eighth lens is 2mm-15 mm; the central thickness of the ninth lens ranges from 5mm to 20 mm; the central thickness of the tenth lens ranges from 5mm to 20 mm; the central thickness of the eleventh lens ranges from 2mm to 15 mm.
The dispersion objective lens 30 is arranged through a double telecentric structure, controls object space telecentricity and image space telecentricity respectively, and can be equivalent to line light sources in a large range, so that dispersion of uniform line light sources is generated, and the brightness and precision consistency of measuring light spots are guaranteed. Meanwhile, the dispersion objective lens 30 is arranged in cooperation with the light source optical fiber 20, so that the angle adaptability, the angle size, the zoom magnification beta and the object numerical aperture NA of the system are effectively improved1In relation to the object-side numerical aperture NA, the smaller the zoom magnification beta is1The larger the image-side numerical aperture NA2The larger the angle, the better the angle adaptability.
In the present embodiment, in the line spectrum confocal sensor, the zoom ratio of the dispersive objective lens 30 is between 0.04 and 0.5, and on the basis, the numerical aperture of the object space is increased as much as possible, and through the cooperation of the two, under the condition of realizing a large line length of the system, the uniformity and the precision of all points on the line are ensured to be consistent, and simultaneously, the large angle adaptability on the target surface is realized, that is, light can return to the original optical fiber channel within the range of 90 degrees ± 35 degrees; the characteristics of large line length, high consistency and large angle are considered.
In addition, the chromatic dispersion objective lens 30 adopts a spherical lens to generate chromatic aberration, corrects other aberration, and is convenient to process and simple to produce.
The reflected light reflected by 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 quantified light wave generates a spectrum peak on the spectrometer 50, and the peak position of the spectrum curve and the wavelength focused on the surface of the object to be measured generate a corresponding relation for subsequent analysis.
In this embodiment, the length of the spectrometer optical fiber 40 is set to be 25mm to 85mm, the specific value of the length is the same as that of the light source optical fiber 20, the reflected light of the measured object passes through the dispersion objective lens 30 and the spectroscope 60 and then reaches the spectrometer optical fiber 40, and the arrangement of the dispersion objective lens 30 ensures that the consistency of the light spots projected by the reflected light of the measured object into the optical fiber can be effectively ensured.
As mentioned above, the consistency of the light spots projected by the spectrometer onto the camera affects the consistency of the light channels at non-central positions, in order to effectively receive the light source projected by the large-size spectrometer optical fiber 40 and ensure the consistency of the light spots 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 for collimating the reflected light to obtain parallel reflected light, and the dispersion component 52 is used for dispersing the parallel reflected light; the second lens group is used for focusing the dispersed reflected light and eliminating chromatic aberration of the reflected light; the object space of the spectrometer is the optical fiber array of the second light-emitting end 42, and the image space of the spectrometer is a spectral image collected by a camera.
The structure of a general spectrometer is generally a slit, a collimating component, a dispersing component, a focusing component, a camera and the like; the slit controls the size of an input light spot, the optical system only corrects the on-axis aberration, and the field of view only has an on-axis field of view. The line spectrum confocal spectrometer needs to simultaneously collimate, disperse, focus and measure the spectra of hundreds of channels, and simultaneously needs to ensure the uniformity and accuracy of each channel.
In order to achieve consistency between channels, the spectrometer of the present embodiment adopts a double telecentric design: the first lens group is telecentric as a long-focus object space, the diameter of a light beam is compressed, the uniformity of each channel after being collimated by the first lens group is ensured, and meanwhile, the off-axis aberration is more easily balanced by adopting a symmetrical structure, and the object space view field is increased; the second lens group is used as a short-focus image space telecentric lens which is matched with the first lens group to form a zooming relation, the imaging is zoomed to be matched with the size of the detector, a proper focal length is formed to focus the spectrum and adapt the detector, and the image space telecentric lens ensures the brightness consistency of all channels on the detector; from the light source, a light homogenizing device, a double telecentric dispersion mirror, a double telecentric spectrometer and the like are respectively arranged to ensure the brightness consistency of the light channel on the image surface of the final detector.
As a preferred scheme, the range of the zoom ratio of the image space and the object space of the spectrometer is 0.1 to 0.8.
As a preferable mode, as shown in fig. 3, 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, which are coaxially disposed; wherein the twelfth lens L12 is used for balancing the spherical aberration of the reflected light and compressing the beam diameter of the reflected light; the thirteenth lens L13 is used to further balance the spherical aberration of the reflected light and to compress the beam diameter of the reflected light again; the fourteenth lens L14 is used to balance distortion, astigmatism and field curvature for the recompressed beam to create a large field of view; the fifteenth lens L15 and the sixteenth lens L16 form a cemented structure for eliminating chromatic aberration of reflected light after field curvature, and cooperate with the fourteenth lens L14 to form a large field of view, and obtain dispersed radiant light;
the second lens group is used for converging the dispersed reflected light, and comprises 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 of a glued structure and are used for eliminating reflected light chromatic aberration after chromatic aberration; the nineteenth lens L19 is configured to balance coma, astigmatism and spherical aberration in the reflected light after chromatic aberration is eliminated, and eliminate distortion; the twentieth lens L20 is used for compensating the spherical aberration and the coma aberration of the reflected light after the distortion is removed, controlling the astigmatism, and compressing and controlling the beam divergence angle of the reflected light after the astigmatism; the twenty-first lens L21 is used for further compressing the beam divergence angle of the reflected light and eliminating astigmatism and distortion; the twenty-second lens L22, the twenty-third lens L23, and the twenty-fourth lens L24 are used to control the spherical aberration and the coma aberration of the reflected light, and further compress the beam divergence angle of the reflected light.
In the first lens group, the twelfth lens L12 is a positive focal length lens, and the focal length value range is 260mm to 280 mm; the thirteenth lens L13 is a positive focal length lens, and the focal length range is 80mm to 110 mm; the fourteenth lens L14 is a negative focal length lens, and the focal length value range is-50 mm to-30 mm; 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 is in the range of-160 mm to-130 mm; the sixteenth lens L16 is a positive focal length lens, and the focal length value range is 50mm to 70 mm; in the second lens group, a seventeenth lens L17 and the eighteenth lens L18 form a cemented lens, wherein the seventeenth lens L17 is a negative focal length lens, and the focal length range is-60 mm to-40 mm; the eighteenth lens L18 is a positive focal length lens, and the focal length value range is 100mm to 120 mm; the nineteenth lens L19 is a positive focal length lens, and the focal length value range is 140mm to 170 mm; the twentieth lens L20 is a positive focal length lens, and the focal length range is 80mm to 110 mm; the twenty-first lens L21 is a positive focal length lens, and the focal length value range is 130mm to 170 mm; the twenty-second lens L22 is a negative focal length lens, and the focal length value range is-50 mm to-30 mm; the twenty-third lens L23 is a positive focal length lens, and the focal length value range is 80mm to 100 mm; the twenty-fourth lens L24 is a positive focal length lens, and the focal length value range is 170mm to 220 mm.
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 and is arranged towards the object space 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 and is arranged towards the object space of the spectrometer; the twenty-first lens L21 is a meniscus lens and is arranged towards the object space of the spectrometer; the twenty-second lens L22 is a plano-concave lens; the twenty-third lens L23 is a plano-convex lens; the twenty-fourth lens L24 is a meniscus lens, disposed towards the object side of the spectrometer.
The reflected light composed of a plurality of point light sources is collimated by the first lens group to form parallel light, and the parallel light is incident to the dispersion component 52, and the dispersion component 52 is used for dispersion of the parallel light.
In addition, the spectral confocal sensor shown in the present invention also takes into account the matching problem of the spectral uniformity of the source fiber 20, the dispersive objective lens 30, the spectrometer fiber 40, and the spectrometer 50; the light source fiber 20 and the spectrometer fiber 40 have the optimal light passing wavelength due to material limitation, the dispersion objective lens 30 has the design wavelength, and the dispersion device in the spectrometer 50 also has the requirement of adapting to the wavelength.
The key point of the embodiment is in the design of the lens, the most important point is in the combination mode of curvature, thickness and material, the large-range and large-angle adaptability is realized, the working distance is longer, and the monochromatic aberration including aberrations such as spherical aberration, coma aberration, field curvature, astigmatism and distortion is controlled on the basis of enlarging the dispersion as much as possible by using the glass combination with different curvatures, thicknesses and materials; the system makes the diffuse speckle approach or reach the diffraction limit level under different wavelengths, has perfect imaging effect on different wavelengths existing in the light source, does not use dispersive devices such as a grating and the like, and realizes dispersion, emission and reception in the same optical path under the coaxial optical path.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments. The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.