A return type multiplication optical path, gas cell and spectrometer

Abstract

The present invention discloses a return-type multiplying optical path, a gas cell and a spectrometer. The return-type multiplying optical path comprises a beam splitter and a beam reflecting lens group. The beam splitter is arranged on one side of the beam reflecting lens group. An incident light beam enters the beam reflecting lens group through the beam splitter, and is reflected back to the beam splitter after multiple reflections in the beam reflecting lens group, and is emitted by the beam splitter as a reflected light beam. The beam splitter is used to separate the incident light beam and the reflected light beam, so that the optical path multiplication can be achieved through the beam reflecting lens group.

Description

Technical Field

[0001] The invention belongs to the field of spectral equipment, and in particular relates to a return-type multiplication optical path, a gas cell and a spectrometer. Background Art

[0002] Gas cells are widely used in analytical chemistry and are one of the core components in the field of quantitative gas spectral analysis. According to Lambert-Beer's law, absorbance is linearly related to optical path length. A longer optical path length will effectively increase the optical absorption signal, increase the signal-to-noise ratio, and thus improve the detection limit of gas detection analysis, which is very important for quantitative gas analysis using laser spectrometers, near-infrared spectrometers, and mid-infrared spectrometers. However, the optical path length of the gas cell cannot simply be increased by increasing the length of the gas cell to increase the optical absorption signal. A longer gas cell will significantly increase the volume of the instrument. On the other hand, an increase in the length of the gas cell will also increase the internal capacity of the gas cell, which will increase the gas measurement time and slow the instrument response speed. For quantitative gas measurement using infrared spectrometers and ultraviolet spectrometers, the requirements for incident light in the gas cell are obviously different from those for using laser spectrometers. When the gas pool incident light comes from the interferometer output of a conventional Fourier transform infrared spectrometer, the spot diameter is usually more than 1 inch. Even after converting the beam diameter, it cannot be as small as the laser spot diameter and has a certain divergence angle. The output spot diameter of the helium-neon laser commonly used in the mid-infrared field is usually less than 0.5 mm, which is more than 50 times smaller than the interferometer output spot diameter of the Fourier transform infrared spectrometer. Therefore, the input spot of the gas cell used for the laser spectrometer is very small, and it is completely unsuitable for the gas cell supporting the conventional infrared spectrometer or ultraviolet spectrometer from the perspective of optical design. In addition, the laser spectrometer can use optical fiber and optical coupling, but different materials of mid-infrared optical fiber are applicable to different wavelength ranges, and it is difficult to meet the wider mid-infrared spectrum of 2.5μm-25μm wavelength range. For example: the transmission range of zirconium fluoride (ZrF4) optical fiber is from 285nm to 4.5μm, the transmission range of indium fluoride (InF3) optical fiber is from 310nm to 5.5μm, the transmission range of sulfide optical fiber is from 1.5μm-6μm, and the transmission range of polycrystalline silver halide infrared optical fiber is from 4μm-18μm. Even the wavelength transmission rate of hollow core optical fiber decreases significantly with the increase of mid-infrared wavelength. Summary of the invention

[0003] In order to solve the above technical problems, the object of the present invention is to provide a return-type multiplying optical path which has a simple structure and can multiply the optical path in a relatively small space.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a return-type multiplying optical path, comprising a beam splitter and a beam reflecting lens group, wherein the beam splitter is arranged on one side of the beam reflecting lens group, an incident light beam enters the beam reflecting lens group through the beam splitter, and is reflected multiple times in the beam reflecting lens group before being reflected back to the beam splitter, and is emitted by the beam splitter as a reflected light beam, and the beam splitter is used to separate the incident light beam and the reflected light beam.

[0005] The beneficial effect of the above technical solution is that the incident light beam passing through the beam splitter is repeatedly reflected by the beam reflecting lens group and then reflected back to the beam splitter, and then the incident light beam and the reflected light beam are separated by the beam splitter, so that the optical path can be doubled by the beam reflecting lens group.

[0006] The light beam reflecting lens assembly in the above technical solution comprises a long strip special-shaped concave spherical reflecting mirror, a first concave spherical reflecting mirror, a second concave spherical reflecting mirror and a third concave spherical reflecting mirror; the long strip special-shaped concave spherical reflecting mirror and the first concave spherical reflecting mirror are sequentially arranged at intervals in the left-right direction, the second concave spherical reflecting mirror and the third concave spherical reflecting mirror are arranged at intervals in the left-right direction and are located at the rear side of the long strip special-shaped concave spherical reflecting mirror, the reflecting surfaces of the long strip special-shaped concave spherical reflecting mirror and the first concave spherical reflecting mirror face backwards, and the reflecting surfaces of the second concave spherical reflecting mirror face the rear side. The reflecting surfaces of the second concave spherical reflector and the third concave spherical reflector face forward, and the second concave spherical reflector is located on a side of the third concave spherical reflector close to the beam splitter, and the beam splitter is arranged on a side of the long strip special-shaped concave spherical reflector away from the first concave spherical reflector. The incident light beam is emitted to the second concave spherical reflector through the beam splitter and is reflected multiple times among the second concave spherical reflector, the long strip special-shaped concave spherical reflector, the third concave spherical reflector and the first concave spherical reflector before being folded back to the beam splitter and emitted by the beam splitter.

[0007] The beneficial effects of the above technical solution are: its structure is simple and the number of parts is small, which can further reduce the space occupied by the light beam reflecting lens group.

[0008] In the above technical solution, the angles between the incident light beam and the reflected light beam and the beam splitter are both 45°.

[0009] The beneficial effect of the above technical solution is that its structure is simple, so that the angle between the incident light beam and the reflected light beam is 90°, which makes it easy to set the light source and the light beam collector.

[0010] The curvature radius of the long strip special-shaped concave spherical reflector, the first concave spherical reflector, the second concave spherical reflector and the third concave spherical reflector in the above technical solution is the same.

[0011] The beneficial effect of the above technical solution is that it makes it more convenient to arrange the long strip special-shaped concave spherical reflector, the first concave spherical reflector, the second concave spherical reflector and the third concave spherical reflector.

[0012] The incident light beam in the above technical solution is an ultraviolet light beam, an infrared light beam or a laser light beam.

[0013] The beneficial effect of the above technical solution is that the return-type multiplying light path has strong adaptability and can be fully applied to light sources of various properties.

[0014] A second object of the present invention is to provide a gas cell with a small volume but a long optical path.

[0015] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a gas pool, comprising a shell, a two-way adjustment device, a three-way adjustment device and a return-type multiplication optical path as described in any one of claims 1 to 4, wherein the return-type multiplication optical path is arranged in the shell, and the second concave spherical reflector and the third concave spherical reflector are arranged at the rear end of the shell, and the long strip of special-shaped concave spherical reflector is arranged at the front end of the shell, the beam splitter is installed on one side of the long strip of special-shaped concave spherical reflector through the three-way adjustment device, the first concave spherical reflector is arranged on the other side of the long strip of special-shaped concave spherical reflector through the two-way adjustment device, and the second concave spherical reflector and the beam splitter are located on the left or right side, and two windows are provided on the shell near the beam splitter, one of which is used to inject an incident light beam, and the other window is used for the reflected light beam to be emitted, the two-way adjustment device is used to adjust the direction of the reflecting surface of the first concave spherical reflector, and the three-way adjustment device is used to adjust the horizontal height of the beam splitter and the direction of its reflecting surface.

[0016] The beneficial effects of the above technical solution are: it has a simple structure, a small size and a long optical path.

[0017] A third object of the present invention is to provide a spectrometer comprising the gas cell as described above.

[0018] The beneficial effect of the above technical solution is that it has high sensitivity and requires a small amount of sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the return-type multiplication optical path described in Example 1 of the present invention;

[0020] Figure 2 Another schematic diagram of the return-type multiplication optical path described in Example 1 of the present invention;

[0021] Figure 3The distribution diagram of the light spots of the incoming light beam and the return light beam on the beam splitter, the first concave spherical reflector and the long strip special-shaped concave spherical reflector in Example 1 of the present invention;

[0022] Figure 4 is a schematic structural diagram of the gas pool described in Example 2 of the present invention;

[0023] Figure 5 Schematic diagram of a retroreflector beam.

[0024] In the figure: 11 beam splitter, 12 beam reflecting lens group, 121 long special-shaped concave spherical reflector, 122 first concave spherical reflector, 123 second concave spherical reflector, 124 third concave spherical reflector, 2 shell, 21 window, 3 two-way adjustment device, 4 three-way adjustment device. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] Example 1

[0027] like Figure 1-Figure 3 As shown, this embodiment provides a return-type multiplication optical path, including a beam splitter 11 and a beam reflecting lens group 12, wherein the beam splitter 11 is arranged on one side of the beam reflecting lens group 12, and an incident light beam is incident into the beam reflecting lens group 12 through the beam splitter 11, and is reflected multiple times in the beam reflecting lens group 12 before being reflected back to the beam splitter 11, and is emitted from the beam splitter 11 as a reflected light beam, and the beam splitter 11 is used to separate the incident light beam and the light beam reflected back to it, so that the incident light beam passing through the beam splitter is repeatedly reflected in the optical path by the beam reflecting lens group and is reflected back to the beam splitter, and then the incident light beam and the reflected light beam are distinguished by the beam splitter, so that the optical path can be multiplied by the beam reflecting lens group.

[0028] The light beam reflecting mirror set 12 in the above technical solution includes a long strip of special-shaped concave spherical reflector 121, a first concave spherical reflector 122, a second concave spherical reflector 123 and a third concave spherical reflector 124; the long strip of special-shaped concave spherical reflector 121 and the first concave spherical reflector 122 are arranged in sequence in the left-right direction, the second concave spherical reflector 123 and the third concave spherical reflector 124 are arranged in the left-right direction and are located at the rear side of the long strip of special-shaped concave spherical reflector 121, the reflecting surfaces of the long strip of special-shaped concave spherical reflector 121 and the first concave spherical reflector 122 face backwards, and the reflecting surfaces of the second concave spherical reflector 123 and the third concave spherical reflector 124 face backwards. Facing forward, the second concave spherical reflector 123 is located on the side of the third concave spherical reflector 124 close to the beam splitter 11, and the beam splitter 11 is arranged on the side of the long strip special-shaped concave spherical reflector 121 away from the first concave spherical reflector 122. The incident light beam is emitted to the second concave spherical reflector 123 through the beam splitter 11 and is reflected back to the beam splitter after multiple reflections among the second concave spherical reflector 123, the long strip special-shaped concave spherical reflector 121, the third concave spherical reflector 124 and the first concave spherical reflector 122, and is emitted by the beam splitter. The structure is simple and the number of parts is small, which can further reduce the space occupied by the light beam reflection lens group.

[0029] The curvature radius of the long strip special-shaped concave spherical reflector 121, the first concave spherical reflector 122, the second concave spherical reflector 123 and the third concave spherical reflector 124 in the above technical solution is the same, which makes it more convenient to set up the long strip special-shaped concave spherical reflector 121, the first concave spherical reflector 122, the second concave spherical reflector 123 and the third concave spherical reflector 124.

[0030] The incident light beam described in the above technical solution is an ultraviolet light beam, an infrared light beam or a laser light beam. The return-type multiplying light path has strong adaptability and can be fully applied to light sources of various properties.

[0031] Among them, from Figure 1 and Figure 2 As shown in , the optical path of the light beam is multiplied by 16 times after multiple reflections in the return multiplication optical path. Of course, the number of light beam reflections can be adjusted by adjusting the beam splitter and the second concave spherical reflector, as shown in Figure 3 It can be found that the optical path of the light beam is multiplied by 34 times after being reflected in the return multiplication optical path.

[0032] in, Figure 3The solid small circle in the middle of the medium-long special-shaped concave spherical reflector, the beam splitter and the first concave spherical reflector represents the light spot of the incoming light beam, while the dotted small circle represents the light spot of the return light beam, wherein the light beam is the incoming light beam at the stage when it is transmitted from the beam splitter to the first concave spherical reflector, and the outgoing light beam at the stage when it is transmitted from the first concave spherical reflector to the beam splitter, wherein the incident light beam, incoming light beam, return light beam and retroreflected light beam refer to the names of the same light beam at different positions.

[0033] Example 2

[0034] like Figure 4 As shown, this embodiment provides a gas pool, including a shell 2, a two-way adjustment device 3, a three-way adjustment device 4 and a return-type multiplication optical path as described in Example 1, wherein the return-type multiplication optical path is arranged in the shell 2 (wherein the shell is a rectangular parallelepiped and is arranged horizontally along the front-to-back direction), and the second concave spherical reflector 123 and the third concave spherical reflector 124 are arranged on the inner bottom wall of the rear end of the shell 2, the long strip special-shaped concave spherical reflector 121 is arranged on the inner bottom wall of the front end of the shell 2, the beam splitter 11 is installed on one side of the long strip special-shaped concave spherical reflector 121 through the three-way adjustment device 4, and the first concave spherical reflector 124 is arranged on the inner bottom wall of the rear end of the shell 2. The reflector 122 is arranged on the other side of the long special-shaped concave spherical reflector 121 through the bidirectional adjustment device 3, and the second concave spherical reflector 123 and the beam splitter 11 are located on the left or right side. Two windows 21 are provided on the shell 2 near the beam splitter 11, one of which is used to inject an incident light beam, and the other is used for the reflected light beam to emit. The bidirectional adjustment device 3 is used to adjust the direction of the reflecting surface of the first concave spherical reflector 122, and the three-way adjustment device 4 is used to adjust the horizontal height of the beam splitter 11 and the direction of its reflecting surface. It has a simple structure, a small size, and a long optical path.

[0035] In the above technical solution, the angles between the incident light beam and the reflected light beam and the beam splitter 11 are both 45°, and the structure is simple, so that the angle between the incident light beam and the reflected light beam is 90°, which is convenient for setting the light source and the beam collector. In particular, in Example 2, the two windows can be respectively set on two adjacent side walls, and the through holes corresponding to the windows are perpendicular to the side walls on the corresponding sides.

[0036] Among them, the reason why the first concave spherical reflector is not replaced by an angle reflector is that although the angle reflector can reflect the light beam, the reflected light beam is always parallel to the incident light beam, and the reflection angle is always maintained at 180°, but the parallel reflection will cause parallel displacement of the light path, which is more suitable for laser spots or parallel light spots. However, if a corner reflector is used to reflect a focused light beam instead of a laser beam or a parallel light beam with a relatively small spot, the focus of the reflected light beam will be reversed, further causing the divergence angle of the return light path returning to the fourth concave spherical reflector 124, the direction of the focal length and the focal length to change, such as Figure 5 As shown in FIG. 1 , the divergence angle, focus and focal length of the return optical path between the fourth concave spherical reflector 124, the strip-shaped concave spherical reflector 121 and the first concave spherical reflector 122 on the return optical path change, so that the optical design of the gas pool cannot work normally. The first concave spherical reflector can be used to adapt to the application of various light beams, and the laser beam or the parallel light beam with a relatively small spot can use an angle reflector, and its reflection diagram is shown in FIG. Figure 5 As shown in a.

[0037] Among them, the two-way adjustment device 3 can adopt a universal ball, and the three-way adjustment device 4 can be composed of a universal ball and a length fine-tuning rod, wherein the length fine-tuning rod is vertically arranged, and the universal ball is installed at the upper end of the length fine-tuning rod. The height of the beam splitter is adjusted by the length fine-tuning rod, and the universal ball thereon is used to adjust the direction of its reflecting surface.

[0038] Example 3

[0039] This embodiment provides a spectrometer including the gas cell as described in Embodiment 2, which has high sensitivity and requires a small amount of sample, wherein the spectrometer can be an infrared spectrometer, an ultraviolet spectrometer or a laser spectrometer.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A return-type multiplying optical path, characterized in that: The invention comprises a beam splitter (11) and a beam reflecting lens group (12), wherein the beam splitter (11) is arranged on one side of the beam reflecting lens group (12), an incident light beam is incident into the beam reflecting lens group (12) through the beam splitter (11), and after multiple reflections in the beam reflecting lens group (12), it is reflected back to the beam splitter (11), and is emitted from the beam splitter (11) as a reflected light beam, and the beam splitter (11) is used to split the incident light beam and the reflected light beam into two The light beam reflecting lens assembly (12) comprises a long strip of special-shaped concave spherical reflecting mirror (121), a first concave spherical reflecting mirror (122), a second concave spherical reflecting mirror (123) and a third concave spherical reflecting mirror (124); the long strip of special-shaped concave spherical reflecting mirror (121) and the first concave spherical reflecting mirror (122) are arranged at intervals from left to right, and the second concave spherical reflecting mirror (123) and the third concave spherical reflecting mirror (124) are arranged at intervals in the left-right direction and are located The rear side of the long strip special-shaped concave spherical reflector (121), the reflective surfaces of the long strip special-shaped concave spherical reflector (121) and the first concave spherical reflector (122) face backwards, the reflective surfaces of the second concave spherical reflector (123) and the third concave spherical reflector (124) face forwards, and the second concave spherical reflector (123) is located on a side of the third concave spherical reflector (124) close to the beam splitter (11), and the beam splitter (11) is arranged on the long strip special-shaped concave spherical reflector (121). On a side of the strip-shaped concave spherical reflector (121) away from the first concave spherical reflector (122), an incident light beam is emitted toward the second concave spherical reflector (123) through the beam splitter (11) and is reflected multiple times between the second concave spherical reflector (123), the strip-shaped concave spherical reflector (121), the third concave spherical reflector (124) and the first concave spherical reflector (122), before being folded back to the beam splitter (11) and emitted from the beam splitter.

2. The return-type multiplying optical path according to claim 1, characterized in that: The angles between the incident light beam and the reflected light beam and the beam splitter (11) are both 45 degrees.

3. The return-type multiplying optical path according to claim 1, characterized in that: The long strip special-shaped concave spherical reflector (121), the first concave spherical reflector (122), the second concave spherical reflector (123) and the third concave spherical reflector (124) have the same curvature radius.

4. The return-type multiplying optical path according to any one of claims 1 to 3, characterized in that: The incident light beam is an ultraviolet light beam, an infrared light beam or a laser light beam.

5. A gas pool, characterized in that: The invention comprises a housing (2), a two-way adjustment device (3), a three-way adjustment device (4), and a return-type multiplying optical path as claimed in any one of claims 1 to 4, wherein the return-type multiplying optical path (1) is arranged in the housing (2), and the second concave spherical reflector (123) and the third concave spherical reflector (124) are arranged at the rear end of the housing (2), the long strip of special-shaped concave spherical reflector (121) is arranged at the front end of the housing (2), the beam splitter (11) is installed on one side of the long strip of special-shaped concave spherical reflector (121) through the three-way adjustment device (4), and the first concave spherical reflector (122) is installed at the front end of the housing (2). A bidirectional adjustment device (3) is arranged on the other side of the long strip special-shaped concave spherical reflector (121), and the second concave spherical reflector (123) and the beam splitter (11) are located on the left or right side. Two windows (21) are arranged on the housing (2) near the beam splitter (11), one of the windows (21) is used for injecting an incident light beam, and the other window (21) is used for allowing a reflected light beam to be emitted. The bidirectional adjustment device (3) is used for adjusting the direction of the reflection surface of the first concave spherical reflector (122), and the three-way adjustment device (4) is used for adjusting the horizontal height of the beam splitter (11) and the direction of its reflection surface.

6. A spectrometer comprising the gas cell according to claim 5.

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