A fiber optic spectrometer
By using a single transmission grating and a mirror for two symmetrical reflections in a fiber optic spectrometer, the problems of low spectral resolution and high cost are solved, achieving the spectral resolution effect of a dual-grating structure on a single-grating structure, and with a more compact optical path.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 赵潇
- Filing Date
- 2025-08-15
- Publication Date
- 2026-05-26
AI Technical Summary
Existing fiber optic spectrometers suffer from low spectral resolution, high cost, and difficulty in miniaturization.
A single transmission grating combined with a reflector is used for two symmetrical reflections to achieve the spectral resolution effect of a dual-grating structure, shortening the optical path size. The beam is adjusted into a parallel beam using a beam collimation unit and a beam deflector, and then diffracted and split by a tilting reflector. Finally, the beam is imaged on the detector array.
It achieves the spectral resolution of a dual-grating structure in terms of cost and size, with a more compact optical path, lower cost than the aforementioned dual-grating structure, and smaller size.
Smart Images
Figure CN224286124U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a spectrometer, and more particularly to a fiber optic spectrometer, belonging to the field of optical instruments. Background Technology
[0002] A spectrometer is a scientific instrument that can decompose polychromatic light (light composed of multiple wavelengths) into a spectrum arranged in wavelength order, and measure, record and analyze the spectrum. By utilizing the principles of light dispersion, diffraction or interference, light of different wavelengths is separated, and information such as the intensity of light of each wavelength is obtained through a detection system, thereby providing data support for the study of the composition, structure and properties of substances.
[0003] In existing technical solutions, there are two main types of grating optical paths used in fiber optic spectrometers that employ transmission gratings.
[0004] The first type is a single grating structure similar to the following patent 1. The light beam is projected onto the grating through the collimating unit. After the grating splits the light, it passes through the focusing lens, and the light spots of different wavelengths are imaged on the detector array.
[0005] The prior art includes patent 1: application number: 202010488918.0. Figure 2 This is an optical system diagram from Patent 1. In this patent, the spectrometer 1 may include, in sequence, a fiber input FIN, a collimator lens CL, a rotating shaft RS, a grating GT, a focusing lens FL, and a focal plane CP. In this embodiment, the fiber input FIN and the collimator lens CL are designed to rotate together, and thus can be defined as a rotating assembly 20. The advantages of this spectrometer structure are: fewer optical path components, simpler structure, and smaller optical structure size.
[0006] Disadvantage: Low spectral resolution.
[0007] The second type of existing technology is the dual-grating structure of the following patents 2, 3 and 4. After the beam passes through the collimation unit, it passes through two transmission gratings in succession, and then the focusing lens images light spots of different wavelengths onto the detector array.
[0008] The second type of grating structure achieves better wavelength separation by using two grating diffraction processes, thus obtaining finer spectral resolution.
[0009] However, because this optical path structure uses two diffraction gratings, its optical structure cost is approximately 1.5 times that of a single grating structure, and its optical path size is relatively large, making miniaturization difficult. Specific patents are as follows:
[0010] Patent Application No. 2: 201810474131.1, Patent Application No. 3: 202210871035.7, Patent Application No. 4: 202410881461.8
[0011] Patent 201810474131.1 is a spectrometer. Figure 3 This is an optical system diagram of Patent 2. The technology includes an entrance slit 31, a collimating element 32 for converting a broadband beam into parallel light; a dispersing device 38, comprising a first dispersing element 33 and a second dispersing element 34, for dispersing parallel light into multiple beams of dispersed light according to wavelength; a focusing element 35 for focusing dispersed light with the same wavelength, and focusing dispersed light with different wavelengths at different positions on its focal plane, with the focused spots of each dispersed light arranged sequentially along a straight line; and a detection device 36 with multiple detection positions on the focal plane, used to detect multiple dispersed lights with different preset wavelengths. When the incident angle of the parallel light entering the dispersing device is constant, the dispersing device and the focusing element cooperate to match the focusing positions of multiple dispersed lights with multiple detection positions 37 in a one-to-one correspondence; among the dispersed lights of different preset wavelengths, the wavenumber difference between any two adjacent beams of dispersed light is equal.
[0012] Patent No. 3202210871035.7 describes a dual-grating folded optical path fiber optic spectrometer. Figure 4 This is an optical system diagram of Patent 3. The patent includes an incident fiber optic port 41, a collimating lens 42, a grating body, a focusing lens 45, and a detector module. The detector module is a linear CCD image sensor 47 or an area CCD image sensor. The grating includes a first transmission grating 43 and a second transmission grating 44. The first transmission grating 43 forms a 135-degree angle with the horizontal direction, and the second transmission grating 44 forms a 45-degree angle with the horizontal direction. Light enters from the incident fiber optic port 41, passes through the collimating lens 42, and then illuminates the first transmission grating 43, undergoing a first diffraction. The diffracted light then enters the second transmission grating 44 for a second diffraction. The second diffracted light is reflected by the focusing lens 45 to the outside of the two transmission gratings, causing the focused light spot to fall onto the photosensitive surface of the CCD image sensor 47 via the cylindrical lens 46.
[0013] Patent 4202410881461.8 is a high-resolution spectrometer with multiple gratings. Figure 5This is an optical system diagram of Patent 4. The patent includes a light source 51, a collimating device 52, a multi-grating dispersion element, a focusing lens group, and a photodetector arranged in sequence. The multi-grating dispersion element 53 specifically includes a first transmission grating 53a and at least one second transmission grating 53b. The first transmission grating 53a is close to the collimating device 52, and the second transmission grating 53b is close to the focusing lens group 54. The light emitted by the light source 51 is processed sequentially through the collimating device 52, a first transmission grating 53a, a second transmission grating 53b, and a focusing lens group 54 before illuminating a photodetector 55.
[0014] The advantages of the second type of patent mentioned above are: the use of a dual-grating structure results in finer spectral resolution, which can be optimized to half the resolution of a single-grating structure. However, the disadvantages are:
[0015] The alpha grating is the most expensive optical component in a spectrometer, accounting for about half of the total cost. The cost of using a dual grating structure is about 1.5 times that of a single grating structure.
[0016] b. After using the dual-grating structure, sufficient angular and length space needs to be left between the two gratings to avoid structural interference, which increases the total length of the optical path and makes it more difficult to achieve miniaturization.
[0017] The two structures mentioned above have two main drawbacks: one is lower spectral resolution, and the other is higher cost and difficulty in miniaturization. The key issue that needs to be addressed is how to achieve miniaturization of the spectrometer at a lower cost. Summary of the Invention
[0018] To address the problems of low spectral resolution and high cost, making miniaturization difficult in existing technologies, this invention provides a fiber optic spectrometer. Its purpose is to achieve the same effect as a dual-grating structure by using a single transmission grating and two symmetrical reflections through a mirror. Moreover, the optical path size is more compact than the aforementioned dual-grating structure, achieving the spectral resolution effect of a dual-grating structure at the cost and size of a single grating.
[0019] The technical solution of this utility model is: a fiber optic spectrometer, comprising a horizontally arranged optical fiber, a beam collimating unit arranged on the vertical line of the emission direction of the optical fiber, a beam deflector arranged obliquely behind the beam deflector, a transmission grating arranged below the beam deflector, the transmission grating and the line parallel to the central wavelength principal ray of the beam collimating unit forming a 45° angle, a pair of tilted mirrors arranged on the light emission side of the transmission grating, the mirror surfaces of the pair of tilted mirrors having different tilt angles, a spot focusing unit arranged on the light incident side of the transmission grating, the emitted beam of the spot focusing unit being parallel to and opposite to the central wavelength principal ray of the beam collimating unit, a detector array arranged on the optical fiber emission side of the spot focusing unit, and the working wavelength of the fiber optic spectrometer being 190~1100nm;
[0020] Furthermore, the beam collimation unit is a spherical lens or an aspherical lens, and the angle between the central wavelength principal ray of the spherical lens or the aspherical lens and the normal of the beam deflection mirror is 40°.
[0021] Furthermore, the line count of the transmission grating can be 966.2 lines per millimeter;
[0022] Furthermore, the pair of tilting mirrors includes mirror one and mirror two, wherein the angle between the normal of mirror one and the principal ray of the center wavelength can be 18.2°, and the angle between the normal of mirror two and the principal ray of the center wavelength can be 24.3°.
[0023] Furthermore, the light spot focusing unit is a spherical lens two, an aspherical lens two, or an aspherical reflecting mirror two;
[0024] Furthermore, the detector array is a planar pixel detector or a linear pixel detector;
[0025] Furthermore, the beam collimating unit can also be replaced with an aspherical reflector along with the beam deflector.
[0026] The advantages of this invention are as follows: By setting a beam collimation unit perpendicular to the direction of fiber optic light emission, the diverging or converging beam can be adjusted into a parallel beam using a spherical or aspherical lens within the beam collimation unit to meet the needs of a specific optical system; by setting a beam deflector at an angle behind the beam collimation unit, the parallel beam after passing through the beam collimation unit can be refracted onto the transmission grating below, shortening the horizontal distance of the parallel beam. After the light passing through the transmission grating undergoes the first diffraction, it is refracted onto a pair of tilting mirrors. Due to the different angles of the two tilting mirrors, the light reflected onto the transmission grating is reflected to different positions on the transmission grating. The reflected light is diffracted a second time in the opposite direction on the transmission grating. After passing through the spot focusing unit, the light beams of different wavelengths after the second diffraction are converged onto the detector array surface to form a tiny spot. The detector array surface is a linear or planar structure formed by arranging multiple detector units (pixels) in a certain pattern. It is the core photosensitive component of the fiber optic spectrometer. Its function is to convert the incident light signal (or other radiation signal) into a processable electrical signal to realize the acquisition of light field distribution, image information or radiation intensity. This invention can achieve the spectral resolution effect of a dual grating at the cost and size of a single grating, and the optical path size is more compact than the aforementioned dual grating structure. Attached Figure Description
[0027] Figure 1 Optical system diagram of this fiber optic spectrometer.
[0028] Figure 2The optical system diagram of Patent 1.
[0029] Figure 3 Optical system diagram of Patent 2.
[0030] Figure 4 The optical system diagram of Patent 3.
[0031] Figure 5 The optical system diagram of Patent 4.
[0032] Labeling Explanation: 10-Fiber optic cable, 11-Beam collimating unit, 12-Beam bending mirror, 13-Transmission grating, 14a-Reflector 1, 14b-Reflector 2, 15-Spot focusing unit, 16-Detector array, 20-Rotating assembly, 31-Incident slit, 32-Collimating element, 33-First dispersive element, 34-Second dispersive element, 35-Focusing element, 36-Detection device, 37-Detection position, 41-Incident fiber port, 42-Collimating mirror, 43-First transmission grating, 44-Second transmission grating, 45-Focusing mirror, 46-Cylindrical mirror, 47-CCD image sensor, 51-Light source, 52-Collimating device, 53-Multi-grating dispersive element, 53a-First transmission grating, 53b-Second transmission grating, 54-Focusing lens group, 55-Photodetector. Detailed Implementation
[0033] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings. The specific orientation is as follows: Figure 1 Describe the relationships between top, bottom, left, and right.
[0034] The technical solution of this utility model is: a fiber optic spectrometer. Figure 1 This is an optical system diagram of the fiber optic spectrometer. The fiber optic spectrometer includes a horizontally arranged optical fiber 10. A beam collimating unit 11 is arranged perpendicular to the emission direction of the light from the optical fiber 10. A beam deflector 12 is arranged obliquely behind the beam deflector 11. A transmission grating 13 is arranged below the beam deflector 12. The transmission grating 13 forms a 45° angle with the parallel line of the central wavelength principal ray of the beam collimating unit 11. A pair of tilted mirrors with different tilt angles are arranged on the light emission side of the transmission grating 13. A spot focusing unit 15 is arranged on the light incident side of the transmission grating 13. The emitted beam of the spot focusing unit 15 is parallel to and opposite to the central wavelength principal ray of the beam collimating unit 11. A detector array 16 is arranged on the fiber emission side of the spot focusing unit 15. The operating wavelength of the fiber optic spectrometer is 190~1100nm.
[0035] The beam collimation unit 11 is either a spherical lens or an aspherical lens, and the angle between the central wavelength principal ray of the spherical lens or the aspherical lens and the normal of the beam deflector 12 is 40°.
[0036] The transmission grating 13 can have a line count of 966.2 lines per millimeter.
[0037] The pair of tilting mirrors includes mirror 14a and mirror 14b, wherein the angle between the normal of mirror 14a and the central wavelength principal ray can be 18.2°, and the angle between the normal of mirror 14b and the central wavelength principal ray can be 24.3°.
[0038] The beam collimation unit 11 can also be replaced with an aspherical mirror along with the beam deflector;
[0039] The detector array 16 is either a surface array pixel detector or a linear array pixel detector.
[0040] The light spot focusing unit 15 is a spherical lens, an aspherical lens, or an aspherical reflector.
[0041] The specific optical path structure is as follows: the emitted light from the input fiber 10 enters the optical path system, becomes collimated light after passing through the beam collimation unit 11, the beam deflection mirror 12 deflects the beam angle, the collimated light undergoes the first diffraction and beam splitting through the transmission grating 13, then undergoes two folds through the first reflector 14a and the second reflector 14b, and undergoes the second diffraction and beam splitting through the transmission grating 13 again, and then the beams of different wavelengths are focused onto the detector array 16 surface by the spot focusing unit 15.
[0042] The advantages of this invention are as follows: By setting a beam collimation unit 11 perpendicular to the emission direction of the optical fiber 10, the diverging or converging beam can be adjusted into a parallel beam using a spherical lens or an aspherical lens in the beam collimation unit 11 to meet the needs of a specific optical system; by setting a beam deflector 12 obliquely behind the beam collimation unit 11, the parallel beam after passing through the beam collimation unit 11 can be refracted onto the transmission grating 13 below, shortening the horizontal distance of the parallel beam. After the light passing through the transmission grating 13 undergoes the first diffraction, it is refracted onto a pair of tilting mirrors. Due to the different setting angles of the two tilting mirrors, mirror 14a and mirror 14b, the light reflected onto the transmission grating 13 is reflected to different... On the transmission grating 13 at the position, the reflected light is diffracted and split a second time in the opposite direction on the transmission grating 13. After the second diffraction and splitting passes through the spot focusing unit 15, the light beams of different wavelengths after the second diffraction are converged onto the detector array 16 to form an image, forming a tiny light spot. The detector array 15 is a linear or planar structure formed by multiple detector units (pixels) arranged in a certain pattern. It is the core photosensitive component of the fiber optic spectrometer. Its function is to convert the incident light signal (or other radiation signal) into a processable electrical signal to realize the acquisition of light field distribution, image information or radiation intensity. This utility model can achieve the spectral resolution effect of a dual grating at the cost and size of a single grating, and the optical path size is more compact than the aforementioned dual grating structure.
Claims
1. A fiber optic spectrometer, comprising a horizontally arranged optical fiber, characterized in that: A beam collimating unit is arranged perpendicular to the emission direction of the optical fiber, and a beam deflector is arranged obliquely behind it. A transmission grating is arranged below the beam deflector. The transmission grating forms a 45° angle with the parallel line of the central wavelength principal ray of the beam collimating unit. A pair of tilted mirrors are arranged on the light emission side of the transmission grating. The tilt angles of the mirror surfaces of the pair of tilted mirrors are different. A spot focusing unit is arranged on the light incident side of the transmission grating. The emitted beam of the spot focusing unit is parallel to and opposite to the central wavelength principal ray of the beam collimating unit. A detector array is arranged on the optical fiber emission side of the spot focusing unit. The operating wavelength of the fiber optic spectrometer is 190~1100nm.
2. The fiber optic spectrometer according to claim 1, characterized in that: The beam collimation unit is either a spherical lens or an aspherical lens, and the angle between the central wavelength principal ray of the spherical lens or the aspherical lens and the normal of the beam deflector is 40°.
3. The fiber optic spectrometer according to claim 1, characterized in that: The transmission grating line count can be 966.2 lines per millimeter.
4. The fiber optic spectrometer according to claim 1, characterized in that: The pair of tilting mirrors includes mirror one and mirror two, wherein the angle between the normal of mirror one and the principal ray of the center wavelength can be 18.2°, and the angle between the normal of mirror two and the principal ray of the center wavelength can be 24.3°.
5. A fiber optic spectrometer according to claim 1, characterized in that: The light spot focusing unit is a spherical lens, an aspherical lens, or an aspherical reflector.
6. A fiber optic spectrometer according to claim 1, characterized in that: The detector array is either a surface array pixel detector or a linear array pixel detector.
7. A fiber optic spectrometer according to claim 2, characterized in that: The beam collimating unit can also be replaced with an aspherical reflector along with the beam deflector.