Spectrometer and confocal displacement sensor

Abstract

The utility model discloses a spectrograph and a confocal displacement sensor, and relates to the technical field of optical devices.The spectrograph comprises a slit, a collimating lens set, a beam splitter prism, an axicon lens and a detector which are sequentially arranged in the light beam propagation direction, and the detector is arranged in a non-diffraction area of the axicon lens; a detection light beam passes through the slit and then is collimated by the collimating lens group, the beam splitter prism deflects light beams with different wavelengths to different degrees and then emits the light beams to form linear dispersion light, the linear dispersion light enters the axicon mirror and is transmitted by the axicon mirror to form non-diffracted light, and the non-diffracted light enters the detector. According to the spectrograph and the confocal displacement sensor provided by the invention, the influence of defocusing on the detection precision of the spectrograph can be avoided.

Description

Technical Field

[0001] This application relates to the technical field of optical devices, and more particularly, to a spectrometer and a confocal displacement sensor. Background Art

[0002] A spectrometer is a precision instrument used to measure and analyze the wavelength distribution and intensity of light emitted by a light source. It reveals the physical and chemical properties of the light source or the sample to be measured by decomposing light and quantifying the light intensity at different wavelengths. Spectrometers are widely used in many fields such as scientific research, industry, medicine, environmental protection, geological exploration, materials science, food safety, aerospace, etc. The structure of a spectrometer generally includes the following key components: 1) Entrance slit: Allows a part of the light source to enter the spectrometer and defines the optical input point of the instrument; 2) Collimating element: Used to convert the light rays from the entrance slit into parallel light beams; 3) Dispersive element: Used to disperse light of different wavelengths to form a spectrum; 4) Focusing element: Focuses the dispersed light beam onto the focal plane to form a spectral image, and each focus or pixel corresponds to a specific wavelength; 5) Detector: Used to detect and record the intensity of light at different wavelengths.

[0003] In the dispersive element of a spectrometer, two methods can be used, namely gratings and prisms. Among them, prisms are mostly used because of their higher energy utilization rate. When a prism is used as the dispersive element in a spectrometer, in order to ensure that the light rays in each wavelength band can be completely focused on the detector, the angles of the focusing element, the principal ray, and the detection surface of the detector need to satisfy the Abbe condition. However, since the use of a prism makes the volume of the entire system relatively large, and there are generally certain errors in the production and assembly of the lens group, and there are also installation errors in the angles and distances of the image sensor, resulting in certain aberrations in the final image and defocus, which leads to a certain degree of uncertainty in the positioning of the spot center and affects the detection accuracy of the spectrometer. Summary of the Utility Model

[0004] The purpose of this application is to provide a spectrometer and a confocal displacement sensor that can avoid the influence of defocus on the detection accuracy of the spectrometer.

[0005] One aspect of the embodiments of this application provides a spectrometer, including a slit, a collimating lens group, a beam-splitting prism, an axicon lens, and a detector arranged in sequence along the light beam propagation direction. The detector is arranged in the non-diffraction region of the axicon lens. The detection light beam passes through the slit and is collimated by the collimating lens group. The beam-splitting prism deflects light beams of different wavelengths to different degrees and then emits them to form linearly dispersed light. The linearly dispersed light enters the axicon lens and is transmitted through the axicon lens to form non-diffracted light, and the non-diffracted light enters the detector.

[0006] As an implementable manner, the non-diffracting region is a preset segment along the propagation direction of the non-diffracting light. Within the non-diffracting region, the spot sizes of the non-diffracting light are the same everywhere, and the light intensities are the same everywhere.

[0007] As an implementable manner, the detector includes a plurality of detection points, and the plurality of detection points correspond one-to-one to the wavelengths of the non-diffracting light.

[0008] As an implementable manner, the detection surface of the detector is perpendicular to the optical axis of the non-diffracting light.

[0009] As an implementable manner, the detection surface of the detector has a preset included angle with the optical axis of the non-diffracting light.

[0010] As an implementable manner, the beam splitting prism is an isosceles triangular prism, and the apex angle of the isosceles triangular prism is between 35° and 60°.

[0011] As an implementable manner, the collimating lens group includes a convex lens, the focal length of the convex lens is between 30 and 100 mm, and the diameter is between 40 and 100 mm.

[0012] As an implementable manner, the collimating lens group includes at least two lenses arranged in sequence along the optical axis, and the combined focal length of the at least two lenses is between 30 and 100 mm.

[0013] As an implementable manner, a circular hole with a diameter between 10 and 50 μm is provided on the slit, and the detection beam passes through the circular hole and enters the collimating lens group.

[0014] On the other hand, an embodiment of the present application provides a confocal displacement sensor, including a light source, a light source beam splitting mirror and a dispersion lens sequentially arranged on the light output side of the light source, and the above-mentioned spectrometer arranged on the transmission side of the light source beam splitting mirror. The white light emitted by the light source is reflected by the light source beam splitting mirror and then passes through the dispersion lens to form a dispersed light and irradiate the target to be measured. After being reflected by the target to be measured, a reflected light is formed. The reflected light propagates through the dispersion lens to the light source beam splitting mirror and then passes through the light source beam splitting mirror and enters the spectrometer to be received by the spectrometer.

[0015] The beneficial effects of the embodiments of the present application include:

[0016] The spectrometer provided by this application includes a slit, a collimating lens group, a spectroprism, an axicon lens, and a detector, which are arranged in sequence along the beam propagation direction. The detector is arranged within the non-diffracting region of the axicon lens. After the detected beam passes through the slit, it is collimated by the collimating lens group. The spectroprism deflects beams of different wavelengths to different degrees and then emits them to form linearly dispersed light. The linearly dispersed light is incident on the axicon lens and forms non-diffracting light after passing through the axicon lens. The non-diffracting light does not diverge during propagation, that is, the shape and size of the light spot remain unchanged during propagation. The non-diffracting light is incident on the detector. In this way, the influence of defocus on the detection accuracy of the spectrometer is avoided. In addition, the non-diffracting light formed by passing through the axicon lens is a series of concentric rings, making its anti-interference ability stronger and the positioning accuracy of the light spot center higher. Even if there is a certain deflection in the installation of the axicon lens and the detector, the center of the ring will not change, and the error caused by the installation can be eliminated after the calibration of the spectrometer. Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0018] Figure 1 Structural schematic diagram of a spectrometer provided by an embodiment of this application;

[0019] Figure 2 Optical path diagram of a spectroprism provided by an embodiment of this application;

[0020] Figure 3 Schematic diagram of the setting method of a detector provided by an embodiment of this application;

[0021] Figure 4 Optical path diagram of an axicon lens provided by an embodiment of this application;

[0022] Figure 5 Cross-sectional light intensity distribution diagram of non-diffracting light provided by an embodiment of this application;

[0023] Figure 6 Light spot diagram of non-diffracting light provided by an embodiment of this application;

[0024] Figure 7 Structural schematic diagram of a confocal displacement sensor provided by an embodiment of this application.

[0025] Icons: 100 - spectrometer; 110 - slit; 120 - collimating lens group; 130 - beam splitting prism; 140 - axicon lens; 150 - detector; 160 - non-diffracting region; 200 - light source; 210 - light source beam splitter; 220 - dispersive lens; 230 - collimating assembly. Detailed implementation mode

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Usually, the components of the embodiments of this application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application that is claimed, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts fall within the scope of protection of this application.

[0028] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0029] In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "center", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0030] The embodiments of this application provide a spectrometer 100, as Figure 1 , Figure 2 and Figure 3 shown, including a slit 110, a collimating lens group 120, a beam splitting prism 130, an axicon lens 140, and a detector 150 arranged in sequence along the beam propagation direction. The detector 150 is arranged within the non-diffracting region 160 of the axicon lens 140. The detection beam passes through the slit 110 and is collimated by the collimating lens group 120. The beam splitting prism 130 deflects beams of different wavelengths to different degrees and then emits them to form linearly dispersed light. The linearly dispersed light is incident on the axicon lens 140 and forms non-diffracting light after passing through the axicon lens 140. The non-diffracting light is incident on the detector 150.

[0031] The spectrometer 100 provided by the embodiments of the present application can be applied in a confocal displacement sensor to detect the reflected light of a target to be measured, and obtain information about the target to be measured according to the information of the reflected light, where the reflected light serves as a detection beam. Specifically, the spectrometer 100 includes a slit 110, a collimating lens group 120, a spectroprism 130, an axicon lens 140, and a detector arranged in sequence along the beam propagation direction. When the spectrometer 100 is in use, the detection beam entering the spectrometer 100 first passes through the slit 110, which is used to control the width and shape of the beam, so that a beam with a specific shape and width passes through the slit 110 and irradiates onto the collimating lens group 120. The collimating lens group 120 collimates the detection beam to form a parallel beam. The parallel beam irradiates onto the spectroprism 130. The spectroprism 130 has different degrees of deflection for beams of different wavelengths, so that the beams of different wavelengths in the detection beam are separated to form linearly dispersed light. The linearly dispersed light is incident on the axicon lens 140. The axicon lens 140 focuses the linearly dispersed light and at the same time makes it form non-diffracting light. The non-diffracting light is incident on the detector 150. The detector 150 determines the wavelength of the non-diffracting light according to the position where the non-diffracting light is projected onto the detector 150, and thus obtains information about the target to be measured according to the wavelength.

[0032] Among them, non-diffracting light refers to that the field distribution of the beam has the form of the first-kind zero-order Bessel function, so that it does not diverge during propagation, that is, the shape and size of the light spot remain unchanged during propagation. In this way, the influence of defocus on the detection accuracy of the spectrometer 100 is avoided.

[0033] In addition, the non-diffracting light formed by passing through the axicon lens 140 is a series of concentric rings, as Figure 6 shown, making its anti-interference ability stronger and the spot center positioning accuracy higher. Even if there is a certain deflection in the installation of the axicon lens 140 and the detector 150, the center of the ring will not change. After calibration of the spectrometer 100, the error caused by the installation can be eliminated.

[0034] Among them, the axicon lens 140 is as Figure 4 shown. The base angle of the axicon lens 140 is θ3 and the diameter is D. When the detection beam collimated by the collimating lens group 120 irradiates onto the axicon lens 140, the axicon lens 140 focuses the beam and at the same time makes it form non-diffracting light in the non-diffracting region 160. The light spot and light intensity distribution formed by the beam in the non-diffracting region 160 remain unchanged. Figure 5 is the distribution diagram of the light intensity of the cross-section of the non-diffracting light along the direction perpendicular to the propagation direction of the non-diffracting light. The intensity of the central light spot is the largest, which is the main light spot, and the intensity of the multi-stage rings on the periphery gradually decreases, that is, the main light spot and multi-stage ring light spots are formed.

[0035] Specifically, the specific structure and form of the detector 150 are not limited in the embodiments of the present application. By way of example, it may be an image sensor for sensing a light beam.

[0036] The spectrometer 100 provided in the present application includes a slit 110, a collimating lens group 120, a spectroprism 130, an axicon lens 140, and a detector 150 that are sequentially arranged along the light beam propagation direction. The detector 150 is disposed within the non-diffracting region 160 of the axicon lens 140 to detect the light beam that passes through the slit 110 and is collimated by the collimating lens group 120. The spectroprism 130 deflects light beams of different wavelengths to different extents and then emits them to form linearly dispersed light. The linearly dispersed light is incident on the axicon lens 140 and forms non-diffracting light after passing through the axicon lens 140. The non-diffracting light does not diverge during propagation, that is, the shape and size of the light spot remain unchanged during propagation. The non-diffracting light is incident on the detector 150, thus avoiding the influence of defocus on the detection accuracy of the spectrometer 100. In addition, the non-diffracting light formed by passing through the axicon lens 140 is a series of concentric rings, making its anti-interference ability stronger and the light spot center positioning accuracy higher. Even if there is a certain deflection in the installation of the axicon lens 140 and the detector 150, the center of the ring will not change, and the error caused by the installation can be eliminated after calibration of the spectrometer 100.

[0037] Optionally, as Figure 4 shown, the non-diffracting region 160 is a preset section along the propagation direction of the non-diffracting light. Within the non-diffracting region 160, the light spot sizes at various positions of the non-diffracting light are the same, and the light intensities at various positions are the same.

[0038] Specifically, the non-diffracting region 160 is a preset section along the propagation direction of the non-diffracting light. As Figure 4 shown, outside the non-diffracting region 160, if the light spot sizes at various positions of the non-diffracting light are the same and the light intensities at various positions are the same, then this non-diffracting light is positive non-diffracting light; when outside the non-diffracting region 160, if the light spot sizes at various positions of the non-diffracting light are different and the light intensities at various positions are different, then this non-diffracting light is approximate non-diffracting light. Compared with positive non-diffracting light, the requirements for the manufacturing of the axicon prism for approximate non-diffracting light are reduced, thereby improving the yield of the axicon prism.

[0039] It can be understood that the fact that the light spot sizes at various positions of the non-diffracting light are the same refers to various positions in the light beam propagation direction. Similarly, the fact that the light intensities at various positions of the non-diffracting light are the same refers to various positions in the light beam propagation direction.

[0040] In an implementable manner of the embodiments of the present application, the detector 150 includes a plurality of detection points, and the plurality of detection points correspond one-to-one to the wavelengths of the non-diffracting light.

[0041] The position where the spot formed by the non-diffracting light is projected onto the detector 150 corresponds one-to-one with the wavelength of the non-diffracting light, so that the wavelength of the non-diffracting light can be determined according to the position where the spot of the non-diffracting light is projected onto the detector 150.

[0042] It can be understood that during the production process of the spectrometer 100, it is necessary to calibrate the correspondence between the monitoring points on the detector 150 and the wavelength so that multiple detection points correspond one-to-one with the wavelength of the non-diffracting light.

[0043] Optionally, as Figure 3 shown by the solid line in Figure 3 the dotted line in is the optical axis of the non-diffracting light, and the detection surface of the detector 150 is perpendicular to the optical axis of the non-diffracting light.

[0044] When the detection surface of the detector 150 is perpendicular to the optical axis of the non-diffracting light, since the area of the detection surface of the detector 150 is fixed, the angular range of the non-diffracting light that the detection surface can receive is maximized ( Figure 3 θ1 in ), and at this time, the spectrometer 100 has the maximum spectral measurement range.

[0045] In an implementable manner of the embodiment of the present application, as Figure 3 shown by the dashed line in Figure 3 the dotted line in is the optical axis of the non-diffracting light, and the detection surface of the detector 150 has a preset included angle with the optical axis of the non-diffracting light.

[0046] When the detection surface of the detector 150 has a preset included angle with the optical axis of the non-diffracting light, that is, when the detection surface of the detector 150 is inclined relative to the optical axis, at this time, the angular range of the light rays of the non-diffracting light that the detector 150 can receive becomes smaller ( Figure 3 θ2 in ), and since the size resolution of the detector 150 is customized, at this time, the spectrometer 100 has a higher spectral resolution.

[0047] The included angle between the detection surface and the optical axis of the non-diffracting light is not limited in the embodiment of the present application, and those skilled in the art can make specific settings according to the actually required range and resolution. By way of example, the included angle between the detection surface and the optical axis of the non-diffracting light can be set to values such as 15° and 30°.

[0048] It should be noted that Figure 3 is a schematic diagram of the setting method of the detector 150, including two states of the detector 150. One is that the detection surface is perpendicular to the optical axis of the non-diffracting light, and the other is that the detection surface has a preset included angle with the optical axis of the non-diffracting light. In actual applications, the detection surface and the non-diffracting light can only have one state at the same time.

[0049] In addition, to improve the adaptability of the spectrometer 100, the detector 150 can be rotatably arranged, and the angle between the detection surface and the optical axis of the non-diffracting light is changed during the rotation of the detector 150. In this way, during the use of the spectrometer 100, the user can adjust the angle between the detection surface and the optical axis of the non-diffracting light according to the actual situation.

[0050] Optionally, as Figure 2 shown, the beam splitting prism 130 is an isosceles triangular prism, and the apex angle of the isosceles triangular prism is between 35° and 60°.

[0051] As can be seen from the foregoing, the beam splitting prism 130 is used to deflect different wavelengths of light beams to different degrees and then emit them to form linearly dispersed light. Among them, the deflection of the detection light beam is related to the inclination degree of the waist of the isosceles triangular prism, that is, related to the apex angle of the isosceles triangular prism. When the apex angle of the isosceles triangular prism is small, the deflection of the light beam is limited, which is not conducive to the separation of light beams of different wavelengths, and it is necessary to increase the distance between the beam splitting prism 130 and the axicon prism, thereby increasing the volume of the spectrometer 100; when the apex angle of the isosceles triangular prism is large, the separation of light beams of different wavelengths is large, and there is a situation where the light beam cannot be refracted. Considering the above two aspects, in the embodiments of the present application, the apex angle of the isosceles triangular prism is set between 35° and 60°. The specific angle is not limited in the embodiments of the present application. By way of example, it can be 35°, 45° and 60°.

[0052] In an implementable manner of the embodiments of the present application, the collimating lens group 120 includes a convex lens, and the focal length of the convex lens is between 30 and 100 mm, and the diameter is between 40 and 100 mm.

[0053] When the collimating lens group 120 includes a convex lens, on the basis of realizing the collimation of the light beam, the number of lenses in the collimating lens group 120 is reduced, which facilitates the assembly of the spectrometer 100. Among them, the focal length of the convex lens being between 30 and 100 mm and the diameter being between 40 and 100 mm can reduce the volume of the spectrometer 100 on the premise of ensuring the collimated light beam.

[0054] As an implementable manner, as Figure 1 shown, the collimating lens group 120 includes at least two lenses arranged in sequence along the optical axis, and the combined focal length of the at least two lenses is between 30 and 100 mm.

[0055] The at least two lenses can correct the aberration while realizing the collimation of the light beam, improve the quality of the light beam, and thus improve the detection accuracy of the spectrometer 100.

[0056] In an implementable manner of the embodiments of the present application, a circular hole with a diameter between 10 and 50 μm is provided on the slit 110, and the detection light beam passes through the circular hole and enters the collimating lens group 120.

[0057] The embodiment of the present application also discloses a confocal displacement sensor, as Figure 7 shown, which includes a light source 200, a light source beam splitter 210 and a dispersion lens 220 sequentially arranged on the light-emitting side of the light source 200, and the above-mentioned spectrometer 100 arranged on the transmission side of the light source beam splitter 210. The white light emitted by the light source 200 is reflected by the light source beam splitter 210 and then forms colored light through the dispersion lens 220 and irradiates the target to be measured. After being reflected by the target to be measured, the reflected light is transmitted through the dispersion lens 220 to the light source beam splitter 210, and then enters the spectrometer 100 through the light source beam splitter 210 and is received by the spectrometer 100.

[0058] Specifically, in practical applications, as Figure 7 shown, a collimation component 230 is arranged between the light source beam splitter 210 and the dispersion lens 220, and a diaphragm is arranged on the light-emitting side of the light source 200. The pinhole diameter of the diaphragm is between 10 - 50 μm. The white light emitted by the light source 200 enters the diaphragm, and after passing through the diaphragm, the white light enters the light source beam splitter 210. The beam splitter reflects part of the white light beam. After being collimated by the collimation component 230, the part of the beam forms a parallel beam. The parallel beam irradiates the surface of the target to be measured after passing through the dispersion lens 220. The reflected and scattered beams from the target to be measured make the reflected and scattered beams enter the dispersion lens 220 again. According to the reversibility of optics, the beam passing through the dispersion lens 220 becomes a parallel light again. The parallel light is focused by the collimation component 230 and then enters the light source beam splitter 210. At this time, part of the focused beam passes through the light source beam splitter 210 and enters the spectrometer 100. Specifically, the beam passing through the light source beam splitter 210 enters the slit 110 of the spectrometer 100. The spectrometer 100 receives the beam passing through the light source beam splitter 210 and processes and detects the beam to realize the detection of the target to be measured.

[0059] Among them, the slit 110 and the diaphragm of the spectrometer 100 and the confocal displacement sensor in the embodiment of the present application are both circular holes. It should be noted that the circular hole cannot be understood as a limitation to the present application. The slit 110 and the diaphragm can also be lines, that is, the spectrometer 100 of the present application can be a point spectrometer 100 or a line spectrometer 100.

[0060] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A spectrometer, characterized in that: The invention comprises a slit, a collimating lens group, a beam splitter, an axicon and a detector which are sequentially arranged along the propagation direction of the light beam. The detector is arranged in the non-diffraction area of ​​the axicon. After passing through the slit, the detection light beam is collimated by the collimating lens group. The beam splitter deflects light beams of different wavelengths to different degrees and then emits linear dispersion light. The linear dispersion light enters the axicon and is transmitted through the axicon to form non-diffraction light. The non-diffraction light enters the detector.

2. The spectrometer according to claim 1, characterized in that The non-diffraction region is a preset section along the propagation direction of the non-diffraction light. In the non-diffraction region, the spot size of the non-diffraction light at each location is the same, and the light intensity at each location is the same.

3. The spectrometer according to claim 1, characterized in that The detector includes a plurality of detection points, and the plurality of detection points correspond one-to-one to the wavelengths of the non-diffracted light.

4. The spectrometer according to claim 1, characterized in that The detection surface of the detector is perpendicular to the optical axis of the non-diffracted light.

5. The spectrometer according to claim 1, characterized in that: A detection surface of the detector and the optical axis of the non-diffracted light have a preset angle.

6. The spectrometer according to claim 1, characterized in that: The dichroic prism is an isosceles triangular prism, and the vertex angle of the isosceles triangular prism is between 35° and 60°.

7. The spectrometer according to claim 1, characterized in that: The collimating lens group comprises a convex lens, the focal length of the convex lens is between 30-100 mm, and the diameter of the convex lens is between 40-100 mm.

8. The spectrometer according to claim 1, characterized in that: The collimating lens group comprises at least two lenses arranged in sequence along the optical axis, and the combined focal length of the at least two lenses is between 30-100 mm.

9. The spectrometer according to claim 1, characterized in that: The slit is provided with a circular hole with a diameter between 10 and 50 μm, and the detection light beam passes through the circular hole and enters the collimating lens group.

10. A confocal displacement sensor, characterized in that: It comprises a light source, a light source beam splitter and a dispersion lens which are sequentially arranged on the light emitting side of the light source, and a spectrometer according to any one of claims 1 to 9 which is arranged on the transmission side of the light source beam splitter, wherein the white light emitted by the light source is reflected by the light source beam splitter and then passes through the dispersion lens to form dispersed light and illuminates a target object to be tested, and then forms reflected light after being reflected by the target object to be tested, and the reflected light is transmitted to the light source beam splitter through the dispersion lens and then enters the spectrometer to be received by the spectrometer after passing through the light source beam splitter.

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