CN212843416U

CN212843416U - Optical system, dispersion lens and spectrum measuring device

Info

Publication number: CN212843416U
Application number: CN202021389582.4U
Authority: CN
Inventors: 周琴; 王瑾; 曹锋; 张勇有; 郑川; 蔡伊霏; 蔡毕; 陈刚; 杨炎锋; 高云峰
Original assignee: Han s Laser Technology Industry Group Co Ltd
Current assignee: Han s Laser Technology Industry Group Co Ltd
Priority date: 2020-07-15
Filing date: 2020-07-15
Publication date: 2021-03-30
Anticipated expiration: 2030-07-15

Abstract

The utility model relates to an optical system, dispersion camera lens and spectral measurement device. The optical system includes in order from an object side to an image side: the first lens is a positive meniscus lens, and the meniscus direction faces the object side; the second lens is a negative meniscus lens, and the meniscus direction faces the image side; a third lens element which is a biconvex positive lens element; a fourth lens element which is a biconvex positive lens element; the fifth lens is a positive meniscus lens, and the meniscus direction faces the object side; a sixth lens that is a biconcave negative lens; the seventh lens is a positive meniscus lens, and the meniscus direction faces the image side; the eighth lens is a negative meniscus lens, and the meniscus direction faces the image side; and a ninth lens which is a positive meniscus lens with a meniscus direction facing the image side. The optical system has good dispersion performance, and can meet the requirement of high-precision measurement when being used in a spectrum measuring device.

Description

Optical system, dispersion lens and spectrum measuring device

Technical Field

The utility model relates to an optical measurement field especially relates to an optical system, dispersion camera lens and spectral measurement device.

Background

With the development of precision machining technology, the requirement for the detection precision of workpiece displacement in the industry is higher and higher, and the traditional displacement sensor comprises a contact sensor and a non-contact sensor.

The touch sensor has high accuracy, but the interaction between the touch sensor and the workpiece is likely to damage the workpiece. A non-contact displacement sensor such as a photoelectric displacement sensor is based on the principle of laser triangulation, wherein laser is reflected on the surface of a workpiece to reach a photosensitive element to form a light spot, and the position change of the light spot is measured to obtain the displacement information of the workpiece.

However, the conventional photoelectric displacement sensor is prone to cause laser waveform confusion or waveform position deviation due to differences in material and angle of the workpiece surface, and further causes measurement errors, and thus it is difficult to meet the requirement of high-precision measurement.

SUMMERY OF THE UTILITY MODEL

Accordingly, it is necessary to provide an optical system, a dispersion lens, and a spectrum measuring apparatus, which are directed to the problems that the conventional photoelectric displacement sensor is prone to generate measurement errors and is difficult to meet the requirement of high-precision measurement.

An optical system comprising, in order from an object side to an image side:

the first lens is a positive meniscus lens, and the meniscus direction of the first lens faces the object side;

the second lens is a negative meniscus lens, and the meniscus direction of the second lens faces to the image side;

a third lens element which is a biconvex positive lens element;

a fourth lens element which is a biconvex positive lens element;

a fifth lens, which is a positive meniscus lens, and the meniscus direction of which faces the object side;

a sixth lens that is a biconcave negative lens;

a seventh lens element which is a positive meniscus lens element and has a meniscus direction facing an image side;

an eighth lens element which is a negative meniscus lens element and has a meniscus direction facing an image side; and

the ninth lens is a positive meniscus lens, and the meniscus direction of the ninth lens faces the image side.

In one embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens have refractive index and abbe number ratios, respectively, of: 1.70/30.1, 1.95/17.9, 1.50/81.6, 1.95/17.9, 1.57/56.1, 1.95/17.9, 1.70/30.1, 1.74/28.3, 1.85/23.8, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

In one embodiment, the second lens and the third lens are cemented, and the fifth lens and the sixth lens are cemented.

In one embodiment, a distance between the first lens element and the second lens element on the optical axis, a distance between the third lens element and the fourth lens element on the optical axis, a distance between the fourth lens element and the fifth lens element on the optical axis, a distance between the sixth lens element and the seventh lens element on the optical axis, a distance between the seventh lens element and the eighth lens element on the optical axis, and a distance between the eighth lens element and the ninth lens element on the optical axis are respectively: 2mm, 15mm, 2mm, 1mm, 2mm, 3mm, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

In one embodiment, the thickness of the first lens element on the optical axis, the thickness of the second lens element on the optical axis, the thickness of the third lens element on the optical axis, the thickness of the fourth lens element on the optical axis, the thickness of the fifth lens element on the optical axis, the thickness of the sixth lens element on the optical axis, the thickness of the seventh lens element on the optical axis, the thickness of the eighth lens element on the optical axis, and the thickness of the ninth lens element on the optical axis are respectively: 4mm, 3mm, 6mm, 10mm, 3mm, 4mm, 2mm, 4mm, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

In one embodiment, in a direction from the object side to the image side, the object side surfaces and the image side surfaces of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are respectively a first curved surface, a second curved surface, a third curved surface, a fourth curved surface, a fifth curved surface, a sixth curved surface, a seventh curved surface, an eighth curved surface, a ninth curved surface, a tenth curved surface, an eleventh curved surface, a twelfth curved surface, a thirteenth curved surface, a fourteenth curved surface, a fifteenth curved surface, a sixteenth curved surface, a seventeenth curved surface, and an eighteenth curved surface, and the radii of curvature of the first curved surface to the eighteenth curved surface are respectively: -64.073mm, -27.642mm, 156.518mm, 50.055mm, 50.055mm, -50.055mm, 59.672mm, -70.380mm, -55.509mm, -36.696mm, -36.696mm, 597.482mm, 20.366mm, 81.841mm, 30.861mm, 13.993mm, 18.851mm, 23.552mm, the allowable tolerance is 10%, the upper deviation is + 5%, and the lower deviation is-5%.

In one embodiment, the focal length of the optical system is: 25.206 ± 5% mm, the numerical aperture of the object space is: NA is 0.22 plus or minus 5%; the working distance is as follows: 19.521 +/-5% mm, and the working wavelength of the optical system is visible light band.

A dispersion lens for dispersing light emitted from a light source, the dispersion lens comprising a lens barrel and the optical system of any of the above embodiments, wherein the optical system is disposed in the lens barrel, and the light emitted from the light source enters the optical system from an object side.

A spectrum measuring device is used for measuring the displacement of a workpiece and comprises a light source, a spectrum light splitting system and the dispersion lens, wherein the light source and the spectrum light splitting system are arranged on the object side of the dispersion lens, the workpiece is positioned on the image side of the dispersion lens, the light source is used for emitting light to the workpiece, and the spectrum light splitting system is used for obtaining the displacement of the workpiece according to the light reflected by the workpiece.

In one embodiment, the spectral splitting system includes a collimating lens, a grating, a focusing lens, and a photosensitive element, the grating is inclined to the propagation direction of the light reflected by the workpiece, the collimating lens is disposed between the dispersion lens and the grating, a connection line between the geometric center of the photosensitive element and the geometric center of the grating is perpendicular to the propagation direction of the light reflected by the workpiece, and the focusing lens is disposed between the grating and the photosensitive element.

The optical system has good dispersion performance by reasonably configuring the surface type and the refractive power of each lens, and polychromatic light can be dispersed and decomposed into monochromatic light with various wavelengths after passing through the optical system. Therefore, the optical system can be applied to a dispersion lens, and the polychromatic light emitted by the light source is dispersed to form monochromatic light with multiple wavelengths after passing through the optical system.

Meanwhile, the optical system can also be applied to a spectrum measuring device, and the polychromatic light emitted by the light source is dispersed by the optical system to form monochromatic light with various wavelengths, reaches the surface of the workpiece and is reflected on the surface of the workpiece. The light reflected by the surface of the workpiece reaches the spectral light splitting system after passing through the optical system again, and the positions of the light with different wavelengths reaching the spectral light splitting system are different because monochromatic light with various wavelengths is reflected on the surface of the workpiece respectively, so that the displacement of the workpiece can be obtained according to the position change of the oscillogram of the light received in the spectral light splitting system. In addition, since monochromatic light with different wavelengths is reflected at different positions on the surface of the workpiece, a waveform diagram formed by the reflected light in the spectral light splitting system is not easily affected by roughness and angle of the surface of the workpiece and ambient stray light. The spectrum detection device is not easy to generate errors in the measurement of the displacement of the workpiece, has higher precision and can meet the requirement of high-precision measurement.

Drawings

FIG. 1 is a schematic view of an optical system according to some embodiments of the present application;

FIG. 2 is a schematic view of a spectral measurement apparatus according to some embodiments of the present application.

100, an optical system; 110. an optical axis; 120. an object surface; l1, first lens; l2, second lens; l3, third lens; l4, fourth lens; l5, fifth lens; l6, sixth lens; l7, seventh lens; l8, eighth lens; l9, ninth lens; s1, a first curved surface; s2, a second curved surface; s3, a third curved surface; s4, a fourth curved surface; s5, a fifth curved surface; s6, a sixth curved surface; s7, a seventh curved surface; s8, an eighth curved surface; s9, a ninth curved surface; s10, tenth curved surface; s11, an eleventh curved surface; s12, a twelfth curved surface; s13, a thirteenth curved surface; s14, a fourteenth curved surface; s15, a fifteenth curved surface; s16, a sixteenth curved surface; s17, a seventeenth curved surface; s18, an eighteenth curved surface; 200. a spectral measuring device; 210. a workpiece; 220. a light source; 230. a fiber coupler; 231. an input end; 232. an output end; 240. a dispersion lens; 241. a lens barrel; 251. a first monochromatic light; 252. a second monochromatic light; 253. a third monochromatic light; 260. a spectral light splitting system; 261. a collimating lens; 262. a grating; 263. a focusing lens; 270. a photosensitive element; 280. and a measuring module.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating an optical system 100 according to some embodiments of the present disclosure, wherein an object plane 120 is located on an object side of the optical system 100, and an opposite side of the object side is an image side of the optical system 100, and light enters the optical system 100 from the object side and exits from the image side of the optical system 100.

Specifically, the optical system 100 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, and a ninth lens L9. In a direction from the object side to the image side, the object-side surface and the image-side surface of the first lens element L1 through the ninth lens element L9 are respectively: the lens comprises a first curved surface S1, a second curved surface S2, a third curved surface S3, a fourth curved surface S4, a fifth curved surface S5, a sixth curved surface S6, a seventh curved surface S7, an eighth curved surface S8, a ninth curved surface S9, a tenth curved surface S10, an eleventh curved surface S11, a twelfth curved surface S12, a thirteenth curved surface S13, a fourteenth curved surface S14, a fifteenth curved surface S15, a sixteenth curved surface S16, a seventeenth curved surface S17 and an eighteenth curved surface S18, namely, the object-side surface of the first lens L1 is the first curved surface S1, and the image-side surface of the first lens L1 is the second curved surface S2.

The first lens element L1 is a positive meniscus lens element, and the first lens element L1 has a meniscus direction facing the object side, i.e., the first lens element L1 has positive refractive power, and the first curved surface S1 is concave and the second curved surface S2 is convex. The second lens element L2 is a negative meniscus lens element, and the meniscus direction of the second lens element L2 is toward the image side, i.e., the second lens element L2 has negative refractive power, the third curved surface S3 is convex, and the fourth curved surface S4 is concave. The third lens element L3 and the fourth lens element L4 are both biconvex positive lenses, i.e., the third lens element L3 and the fourth lens element L4 both have positive refractive power, and the fifth curved surface S5, the sixth curved surface S6, the seventh curved surface S7, and the eighth curved surface S8 are convex surfaces. The fifth lens element L5 is a positive meniscus lens element, and the fifth lens element L5 has a meniscus direction facing the object side, i.e., the fifth lens element L5 has positive refractive power, the ninth curved surface S9 is concave, and the tenth curved surface S10 is convex. The sixth lens element L6 is a biconcave negative lens element, i.e., the sixth lens element L6 has negative refractive power, and the eleventh curved surface S11 and the twelfth curved surface S12 are both concave. The seventh lens element L7 is a meniscus positive lens element, and the meniscus direction of the seventh lens element L7 is toward the image side, i.e., the seventh lens element L7 has positive refractive power, the thirteenth curved surface S13 is convex, and the fourteenth curved surface S14 is concave. The eighth lens element L8 is a negative meniscus lens element, and the eighth lens element L8 is oriented towards the image side, i.e., the eighth lens element L8 has negative refractive power, and the fifteenth curved surface S15 is convex and the sixteenth curved surface S16 is concave. The ninth lens element L9 is a positive meniscus lens element, and the ninth lens element L9 is oriented towards the image side, i.e., the ninth lens element L9 has positive refractive power, and the seventeenth curved surface S17 is convex and the eighteenth curved surface S18 is concave.

In the present application, the lenses of the optical system 100 are disposed coaxially, and the axis of each lens is the optical axis 110 of the optical system 100.

In the optical system 100, the surface shape and the refractive power of each lens are appropriately arranged, so that the optical system 100 has good dispersion characteristics, and the polychromatic light can be dispersed and decomposed into monochromatic light with multiple wavelengths after passing through the optical system 100. Specifically, when the polychromatic light is white light, the white light undergoes spectral dispersion after passing through the optical system 100 to form monochromatic light with continuously changing wavelengths, and since the refractive indexes of the monochromatic light with different wavelengths in the lens are different, the focusing point of each monochromatic light on the image side is different, and the focusing points of the plurality of monochromatic lights on the image side are sequentially arranged on the optical axis 110.

Further, in some embodiments, the ratios of the refractive index to the abbe number of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are respectively: nd1 Vd1 ═ 1.70/30.1 ± 5%, Nd 2: vd2 ═ 1.95/17.9 ± 5%, Nd 3: vd3 ═ 1.50/81.6 ± 5%, Nd 4: vd4 is 1.95/17.9 ± 5%, Nd5/Vd5 is 1.57/56.1 ± 5%, Nd6/Vd6 is 1.95/17.9 ± 5%, Nd7/Vd7 is 1.70/30.1 ± 5%, Nd8/Vd8 is 1.74/28.3 ± 5%, and Nd9/Vd9 is 1.85/23.8 ± 5%. By reasonably configuring the refractive index and abbe number of each lens in the optical system 100, the dispersion performance of the optical system 100 can be further improved, so that the light can be better decomposed into monochromatic light with different wavelengths through the polychromatic light of the optical system 100.

Also, referring to fig. 1, in some embodiments, the thickness of the first lens L1 on the optical axis 110 is: d1 ═ 4 ± 5% mm; the thickness of the second lens L2 on the optical axis 110 is: d3 ═ 3 ± 5% mm; the thickness of the third lens L3 on the optical axis 110 is: d4 ═ 6 ± 5% mm; the thickness of the fourth lens element L4 on the optical axis 110 is: d6 is 10 ± 5% mm; the thickness of the fifth lens L5 on the optical axis 110 is: d8 ═ 3 ± 5% mm; the thickness of the sixth lens element L6 on the optical axis 110 is: d9 ═ 3 ± 5% mm; the thickness of the seventh lens element L7 on the optical axis 110 is: d11 ═ 4 ± 5% mm; the thickness of the eighth lens element L8 on the optical axis 110 is: d13 is 2 ± 5% mm; the thickness of the ninth lens L9 on the optical axis 110 is: d15 ═ 4. + -. 5% mm.

In some embodiments, the radii of curvature of the first curved surface S1 to the eighteenth curved surface S18 in the object-to-image direction are: r1 ═ 64.073mm, R2 ═ 27.642mm, R3 ═ 156.518mm, R4 ═ 50.055mm, R5 ═ 50.055mm, R6 ═ 50.055mm, R7 ═ 59.672mm, R8 ═ 70.380mm, R9 ═ 55.509mm, R10 ═ 36.696mm, R11 ═ 36.696mm, R12 ═ 597.482mm, R13 ═ 20.366mm, R14 ═ 81.841mm, R15 ═ 30.861mm, R16 ═ 13.993mm, R17 ═ 18.851mm, R18 ═ 23.552mm, and the allowable tolerance for the radii of curvature of the object side and the image side of each lens is 10%, the upper deviation is + 5%, and the lower deviation is-5%.

In the embodiment shown in fig. 1, the object-side surface and the image-side surface of each lens, i.e., the first curved surface S1 to the eighteenth curved surface S18, are all spherical surfaces, and in this case, the object-side surface and the image-side surface of each lens have the same radius of curvature at the optical axis 110 and at the circumference. In other embodiments, some of the first curved surface S1 to the eighteenth curved surface S18 may be aspheric surfaces, so that the use of the aspheric surface can improve the flexibility of lens design, effectively correct spherical aberration, and improve imaging quality. At this time, the curvature radius of the aspherical surface indicates the curvature radius of the aspherical surface at the optical axis 110.

In some embodiments, the distance between the second lens L2 and the third lens L3 on the optical axis 110 is 0, the distance between the fifth lens L5 and the sixth lens L6 on the optical axis 110 is 0, the second lens L2 is disposed by being cemented with the third lens L3, and the fifth lens L5 is disposed by being cemented with the sixth lens L6. By providing the cemented lens in the optical system 100, it is possible to suppress the occurrence of chromatic aberration in the optical system 100 and to increase the reduction degree of the image formed by the optical system 100.

Further, in some embodiments, a distance between the object plane 120 and the first lens element L1 of the optical system 100 on the optical axis 110, that is, a distance between the object plane 120 and the first curved surface S1, is: d0 is 40.678 ± 5% mm; the distance between the first lens L1 and the second lens L2 on the optical axis 110, i.e., the distance between the second curved surface S2 and the third curved surface S3 on the optical axis 110, is: d2 is 2 ± 5% mm; the distances between the third lens L3 and the fourth lens L4 on the optical axis 110 are: d5 ═ 15 ± 5% mm; the distances between the fourth lens L4 and the fifth lens L5 on the optical axis 110 are: d7 is 2 ± 5% mm; the distances between the sixth lens L6 and the seventh lens L7 on the optical axis 110 are: d10 is 1 ± 5% mm; the distances between the seventh lens L7 and the eighth lens L8 on the optical axis 110 are: d12 is 2 ± 5% mm; the distance d14 of the eighth lens L8 to the ninth lens L9 on the optical axis 110 is 3 ± 5% mm. By reasonably controlling the central thickness of each lens in the optical system 100 and the distance between the lenses on the optical axis 110, the dispersion performance of the optical system 100 is improved, and the size of the optical system 100 in the direction of the optical axis 110 can be shortened, which is beneficial to the miniaturization design of the optical system 100.

In addition, in some embodiments, each lens in the optical system 100 may be made of glass or plastic. The use of a plastic lens can reduce the weight of the optical system 100 and reduce the production cost, which is advantageous for realizing a compact design of the optical system 100. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

Referring to fig. 1 and 2, in some embodiments, the optical system 100 can be assembled with the lens barrel 241 to form the dispersion lens 240, only the lens barrel 241 of the dispersion lens 240 is shown in fig. 2, and the optical system 100 is disposed in the lens barrel 241. Since the optical system 100 has good dispersion performance, the dispersion lens 240 can disperse the light emitted by the light source 220, and the polychromatic light emitted by the light source 220 enters the optical system 100 from the object side of the optical system 100 and is emitted from the image side of the optical system 100 to be decomposed into a plurality of monochromatic lights with different wavelengths.

Further, referring to fig. 1 and 2, fig. 2 shows a schematic view of a spectral measuring device 200 according to some embodiments of the present application, the spectral measuring device 200 being used to measure a displacement of a workpiece 210. Specifically, the spectrum measuring apparatus 200 includes a light source 220, a fiber coupler 230, a dispersion lens 240, a spectrum splitting system 260, and a measuring module 280. The optical fiber coupler 230 has an input end 231 and an output end 232 that are disposed opposite to each other, the light source 220 and the spectral splitting system 260 are both connected to the input end 231 of the optical fiber coupler 230, the dispersive lens 240 is connected to the output end 232 of the optical fiber coupler 230, and the object plane 120 of the optical system 100 is overlapped with the end face of the output end 232 of the optical fiber coupler 230, that is, the light source 220 and the spectral splitting system 260 are both disposed on the object side of the optical system 100.

It should be noted that, in the present application, a connection between two optical elements is described, and it is understood that the two optical elements are connected by a connecting element such as an optical fiber, and light emitted from one optical element can reach the other optical element through the connecting element.

Light emitted from the light source 220 enters the optical fiber from the input end 231 of the fiber coupler 230, and exits from the output end 232 of the fiber coupler 230, and enters the optical system 100 from the object side of the optical system 100. After being adjusted by the optical system 100, the light is emitted from the image side of the optical system 100 and is dispersed, and is decomposed into a plurality of monochromatic lights with different wavelengths, such as the first monochromatic light 251, the second monochromatic light 252, and the third monochromatic light 253 shown in fig. 2. The monochromatic light strikes the surface of the workpiece 210 and is reflected by the surface of the workpiece 210. Because the confocal condition and the reversible principle of the optical path are satisfied, the light reflected by the surface of the workpiece 210 enters the optical system 100 from the image side, and exits from the object side of the optical system 100, enters the optical fiber coupler 230 through the output end 232 of the optical fiber coupler 230, and exits from the input end 231 of the optical fiber coupler 230 and enters the spectral splitting system 260.

Further, in some embodiments, the spectral splitting system 260 includes a collimating lens 261, a grating 262, a focusing lens 263, and a photosensitive element 270. The collimating lens 261 is connected to the input end 231 of the fiber coupler 230, and the collimating lens 261 is located between the fiber coupler 230 and the grating 262 in the propagation direction of the light reflected by the surface of the workpiece 210. The grating 262 is inclined to the direction of propagation of the light reflected from the surface of the workpiece 210. The focusing lens 263 is disposed between the grating 262 and the photosensitive element 270, and a connection line between the geometric center of the photosensitive element 270 and the geometric center of the grating 262 is perpendicular to the propagation direction of the light reflected by the workpiece 210.

The light reflected from the surface of the workpiece 210 is emitted from the input end 231 of the fiber coupler 230, passes through the collimating lens 261, and forms a plurality of parallel beams with different wavelengths, which reach the surface of the grating 262, are reflected by the surface of the grating 262, and then are emitted toward the focusing lens 263. The light beams are focused by the focusing lens 263 and then converged on the photosensitive surface of the photosensitive element 270, and the light beams with different wavelengths are converged at different positions on the photosensitive element 270. The measuring module 280 is electrically connected to the photosensitive element 270, the photosensitive element 270 converts an image formed on the photosensitive surface into an electrical signal and transmits the electrical signal to the measuring module 280, and the measuring module 280 establishes a corresponding wavelength distribution diagram according to the electrical signal output by the photosensitive element 270.

Referring to fig. 2, it can be understood that the different wavelengths of monochromatic light reach different positions on the surface of the workpiece 210 when the focusing point on the image side of the dispersing lens 240 is different. Therefore, monochromatic light with different wavelengths reflected by the surface of the workpiece 210 is reflected by the grating 262 and then also strikes different positions of the photosensitive element 270. In addition, since the distances between the focus point of the monochromatic light with different wavelengths on the image side of the dispersion lens 240 and the surface of the workpiece 210 are different, the intensities of the monochromatic light with different wavelengths reflected from the surface of the workpiece 210 are also different. The monochromatic light having the focus point on the image side of the dispersing lens 240 just on the surface of the workpiece 210 has the maximum intensity after being reflected by the surface of the workpiece 210, such as the second monochromatic light 252 in fig. 2. The corresponding light intensity distribution waveform can be drawn according to the different intensities of the light reaching different positions on the photosensitive element 270.

Further, when the workpiece 210 moves, the monochromatic light whose focal point is just on the surface of the workpiece 210 changes, so that the light distribution positions of different intensities on the photosensitive element 270 change as a whole. The displacement of the workpiece 210 can be obtained by comparing the change in the light intensity distribution waveform corresponding to the light distribution on the photosensitive element 270 before and after the movement of the workpiece 210. Since monochromatic light with different wavelengths is reflected at different positions on the surface of the workpiece 210, a light intensity distribution oscillogram formed by the reflected light in the spectral light splitting system 260 is not easily affected by roughness and angle of the surface of the workpiece 210 and environmental stray light, so that the spectral monitoring device is not easily subjected to error in detection of displacement of the workpiece 210, and the requirement of high-precision measurement can be met.

It is understood that due to factors such as the surface tilt of the workpiece 210 and the different focusing points of the plurality of monochromatic lights with different wavelengths on the image side of the dispersing lens 240, a part of the monochromatic lights cannot enter the fiber coupler 230 to reach the spectral splitting system 260 after being reflected. The monochromatic light with the focusing point just on the surface of the workpiece 210 can be reflected by the surface of the workpiece 210 and enter the spectral beam splitting system 260 through the optical fiber coupler 230, and the displacement of the workpiece 210 can be measured by comparing the wavelength values of the maximum intensity light received by the photosensitive element 270 before and after the workpiece 210 moves.

Further, in some embodiments, the focal length of the optical system 100 is: and f is 25.206 +/-5% mm. The numerical aperture of the object space of the optical system 100 is NA 0.22 ± 5%, which is understood to be the numerical aperture of the space between the output end 232 of the optical fiber coupler 230 and the first curved surface S1. The working distance of the optical system 100 is: 19.521 + -5% mm, i.e., the distance in the direction of the optical axis 110 between the focus points closest to the optical system 100 among the focus points on the image side of the eighteenth curved surface S18 to the monochromatic light of the multiple wavelengths. The operating wavelength of the optical system 100 is in the visible band.

Additionally, in some embodiments, the photosensitive element 270 may be a Charge Coupled Device (CCD) or a complementary metal oxide semiconductor device (CMOS Sensor). The collimating lens 261 can be a convex lens, and the focusing lens 263 can also be a convex lens. Of course, in other embodiments, the collimating lens 261 may also be a lens assembly composed of a plurality of lenses, and the focusing lens 263 may also be a lens assembly composed of a plurality of lenses, as long as the collimating lens 261 has positive refractive power and can collimate the light reflected by the surface of the workpiece 210 to form a parallel light beam, and the focusing lens 263 also has refractive power and can focus the light reflected by the grating 262 on the photosensitive element 270. Moreover, in some embodiments, the light source 220 may be a white light source 220, and the white light emitted by the light source 220 can form a plurality of monochromatic lights with continuously changing wavelengths after passing through the dispersion lens 240, and a continuous light intensity distribution waveform can also be formed on the photosensitive element 270, and the continuous wavelength change can improve the measurement accuracy of the displacement of the workpiece 210. In some embodiments, the measurement module 280 may be a microcomputer integrated in the spectral measurement device 200.

It should be noted that, in the fiber coupler 230, two optical channels should be provided, one of which is used for transmitting the light emitted from the light source 220 to the dispersing lens 240, and the other is used for transmitting the light reflected by the surface of the workpiece 210 to the spectral splitting system 260.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical system comprising, in order from an object side to an image side:

a third lens element which is a biconvex positive lens element;

a fourth lens element which is a biconvex positive lens element;

a sixth lens that is a biconcave negative lens;

2. The optical system according to claim 1, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens have refractive index and abbe number ratios of: 1.70/30.1, 1.95/17.9, 1.50/81.6, 1.95/17.9, 1.57/56.1, 1.95/17.9, 1.70/30.1, 1.74/28.3, 1.85/23.8, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

3. The optical system of claim 1, wherein the second lens is cemented to the third lens, and the fifth lens is cemented to the sixth lens.

4. The optical system of claim 3, wherein an axial distance between the first lens element and the second lens element, an axial distance between the third lens element and the fourth lens element, an axial distance between the fourth lens element and the fifth lens element, an axial distance between the sixth lens element and the seventh lens element, an axial distance between the seventh lens element and the eighth lens element, and an axial distance between the eighth lens element and the ninth lens element are respectively: 2mm, 15mm, 2mm, 1mm, 2mm, 3mm, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

5. The optical system of claim 1, wherein a thickness of the first lens element, a thickness of the second lens element, a thickness of the third lens element, a thickness of the fourth lens element, a thickness of the fifth lens element, a thickness of the sixth lens element, a thickness of the seventh lens element, a thickness of the eighth lens element, and a thickness of the ninth lens element are respectively: 4mm, 3mm, 6mm, 10mm, 3mm, 4mm, 2mm, 4mm, with an allowable tolerance of 10%, an upper deviation of + 5%, and a lower deviation of-5%.

6. The optical system according to claim 1, wherein object-side surfaces and image-side surfaces of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens in a direction from an object side to an image side are respectively a first curved surface, a second curved surface, a third curved surface, a fourth curved surface, a fifth curved surface, a sixth curved surface, a seventh curved surface, an eighth curved surface, a ninth curved surface, a tenth curved surface, an eleventh curved surface, a twelfth curved surface, a thirteenth curved surface, a fourteenth curved surface, a fifteenth curved surface, a sixteenth curved surface, a seventeenth curved surface, and an eighteenth curved surface, and radii of curvature of the first curved surface to the eighteenth curved surface are respectively: -64.073mm, -27.642mm, 156.518mm, 50.055mm, 50.055mm, -50.055mm, 59.672mm, -70.380mm, -55.509mm, -36.696mm, -36.696mm, 597.482mm, 20.366mm, 81.841mm, 30.861mm, 13.993mm, 18.851mm, 23.552mm, the allowable tolerance is 10%, the upper deviation is + 5%, and the lower deviation is-5%.

7. An optical system according to any one of claims 1-6, characterized in that the focal length of the optical system is: 25.206 ± 5% mm, the numerical aperture of the object space is: NA is 0.22 plus or minus 5%; the working distance is as follows: 19.521 +/-5% mm, and the working wavelength of the optical system is visible light band.

8. A dispersion lens for dispersing light from a light source, wherein the dispersion lens comprises a lens barrel and the optical system of any one of claims 1 to 7, the optical system being disposed in the lens barrel, and light from the light source entering the optical system from an object side.

9. A spectral measurement device for measuring a displacement of a workpiece, wherein the spectral measurement device comprises a light source, a spectral splitting system and the dispersing lens of claim 8, the light source and the spectral splitting system are disposed on an object side of the dispersing lens, the workpiece is located on an image side of the dispersing lens, the light source is configured to emit light to the workpiece, and the spectral splitting system is configured to obtain the displacement of the workpiece according to the light reflected by the workpiece.

10. The apparatus according to claim 9, wherein the spectral measurement system includes a collimating lens, a grating, a focusing lens, and a photosensitive element, the grating is inclined to the propagation direction of the light reflected by the workpiece, the collimating lens is disposed between the dispersing lens and the grating, a line between the geometric center of the photosensitive element and the geometric center of the grating is perpendicular to the propagation direction of the light reflected by the workpiece, and the focusing lens is disposed between the grating and the photosensitive element.