Enhanced gas Raman spectrum measuring device based on folding type multi-reflection gas chamber

Abstract

The utility model discloses an enhanced gas Raman spectrum measuring device based on a folding multi-reflection gas chamber in the field of spectrum measurement. The enhanced gas Raman spectrum measuring device comprises a laser, a laser beam shrinking device, a head-end cavity mirror, a folding reflector, a tail-end cavity mirror, a reflector fixing frame, a signal collecting reflector, a Raman probe, a Raman gas pool main body and a spectrograph. A head-end cavity mirror and a tail-end cavity mirror in the measuring device are located at the same end, multiple times of reflection are carried out among the head-end cavity mirror, a folding reflector and the tail-end cavity mirror, a converged light beam is finally formed in the center of the folding reflector, and a laser beam shrinking device is fixed to a reflector fixing frame and is aligned with a light through hole in the head-end cavity mirror. Fixing at a certain incident angle; the head-end cavity mirror, the folding reflector and the tail-end cavity mirror are fixed at certain angles, so that light beams are reflected back and forth among the three reflectors for multiple times, and the light beam convergence center of the head-end cavity mirror and the light beam convergence center of the tail-end cavity mirror are close to each other but not coincide with each other.

Description

Technical Field

[0001] The utility model relates to the technical field of spectrum measurement, in particular to a gas Raman spectrum measurement device based on a folded multiple reflection gas chamber. Background Art

[0002] Laser Raman spectroscopy is a highly sensitive method widely used for gas composition analysis. It utilizes laser light to illuminate a gas, generating the Raman effect. Gas composition is determined by measuring the wavelength of the Raman scattered light, and gas concentration is determined by measuring the intensity of the scattered light. Compared to other spectroscopic gas detection methods (such as infrared absorption spectroscopy and photoacoustic spectroscopy), Raman spectroscopy utilizes a single laser wavelength to simultaneously measure multi-component gas mixtures. Furthermore, the Raman peak of water vapor is relatively distant from other gases, making its presence in gas samples less susceptible to Raman spectroscopy. Therefore, Raman spectroscopy holds significant application value in environmental monitoring, industrial process control, and scientific research.

[0003] Conventional gas Raman spectroscopy devices typically employ a straight-tube structure, where the laser beam undergoes a single or limited number of reflections within the gas cell. This results in low laser energy utilization and low measurement sensitivity. Furthermore, the straight-tube design often requires a large gas cell, making the device difficult to install and carry, limiting its application for rapid on-site testing.

[0004] To improve the sensitivity and portability of gas Raman spectroscopy, researchers have attempted various improvements. For example, increasing the laser power or extending the optical path to increase signal strength can increase the complexity and energy consumption of the equipment, and these methods often increase the requirements for the laser. Another approach is to use multiple channels or multiple reflections, but existing multi-reflection designs are often complex in structure, making them difficult to miniaturize and lightweight. For example, patent CN202110528906.0, while achieving multiple laser reflections, uses multiple mirrors, resulting in a complex structure and difficult debugging and installation.

[0005] In recent years, with the advancement of optical components and spectrometer technology, folded optical path design has gradually attracted attention. The folded design can achieve multiple reflections of the light beam within a limited range, thereby effectively extending the optical path and improving the utilization rate of the laser energy. However, the existing folded design still has deficiencies in mechanical structure, optical path design, and signal collection, making it difficult to achieve high-sensitivity gas detection. For example, patent CN202110528906.0 designs a folded multi-reflection cavity, but still uses an axial signal collection method, which cannot efficiently collect Raman signals.

[0006] In response to the above technical problems, the utility model proposes a new type of gas Raman spectroscopy measurement device. By adopting a folded multi-reflection gas chamber design, combined with an optimized mechanical structure and optical path design and signal collection scheme, it not only effectively reduces the volume of the Raman gas cell, but also significantly improves the number of laser reflections and measurement sensitivity, meeting the needs of high-precision, portable detection of multi-component gases.

[0007] In summary, the shortcomings of the existing technology and market demand provide the background and motivation for the proposal of this utility model. Through innovative design ideas and technical means, this utility model aims to provide a compact, highly sensitive, and easy-to-install and portable gas Raman spectroscopy measurement device to promote the further development of gas detection technology. Utility Model Content

[0008] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and in the abstract and title of the present invention to avoid obscuring the purpose of this section, the abstract and the title of the utility model, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0009] The purpose of the present invention is to address the technical problems existing in the background technology. The present invention proposes a gas Raman spectroscopy measurement device based on a folded multiple-reflection gas chamber. The purpose of the present invention is to provide a new folded laser Raman gas cell for gas Raman signal enhancement, which not only causes the laser in the cavity to reflect multiple times, but also each reflection of the light beam passes approximately through the center of the folding reflector, thereby improving the laser intensity at this position, enhancing the intensity of the gas Raman signal collected laterally, and realizing high-sensitivity detection of trace gases.

[0010] The utility model proposes a gas Raman spectroscopy measurement device based on a folded multiple-reflection gas chamber, comprising a laser and a Raman gas cell body. The laser emission end is provided with a laser beam reduction device. Two reflector fixing frames are connected to the Raman gas cell body. One reflector fixing frame is rotatably connected to a folding reflector, and the other reflector fixing frame is connected to a head-end cavity mirror and an end-end cavity mirror. A Raman probe is connected to one side of the Raman gas cell body, and a signal collection reflector is provided in the Raman gas cell body.

[0011] The head-end cavity mirror and the end cavity mirror have the same size and focal length, and their relative positions are obtained as follows: the head-end cavity mirror and the end cavity mirror are placed opposite each other with a spacing of 4 times the focal length; the head-end cavity mirror is rotated clockwise by a small angle to achieve a deviation of the cavity mirror center; the end cavity mirror is rotated around the cavity center by a certain angle so that the two cavity mirrors are located on the same side of the cavity and at a close distance; the plane reflector is located at the center of the cavity and rotated counterclockwise by a fixed angle so that the incident light can be reflected multiple times between the head-end cavity mirror and the end cavity mirror.

[0012] By adopting the above technical solution, this solution can repeatedly reflect the laser between the head-end cavity mirror, the end-end cavity mirror and the folding reflector after the laser is emitted into the Raman gas cell body through the mutual reflection effect of the combination of the head-end cavity mirror and the end-end cavity mirror and the folding reflector, thereby forming a laser matrix effect. When the gas inside the Raman gas cell body changes, it can affect the refraction of the laser. The dense laser matrix can enable trace gas to be detected by laser at any position inside the Raman gas cell body.

[0013] Preferably, the emitting end of the Raman probe faces the signal collecting reflector, and one side of the emitting end of the Raman probe is communicatively connected to a spectrometer.

[0014] By adopting the above technical solution, this solution can compare and identify the laser information emitted and received by the Raman probe through a spectrometer, thereby analyzing the gas inside the Raman gas cell body based on the comparison of the emitted laser and the laser information returned after being reflected by the signal collection mirror.

[0015] Preferably, the Raman probe includes a laser emitter and a laser receiver, both of which are oriented toward the signal collecting reflector, and the laser emitter and the laser receiver are communicatively connected to the spectrometer via a cable.

[0016] By adopting the above technical solution, this solution can prevent the device from being affected by external detection equipment during the process of spectral analysis of the gas inside the Raman gas cell body through independent transmitters and receivers, thereby avoiding problems such as errors introduced from the outside of the device.

[0017] Preferably, the laser beam reduction device includes a beam reduction lens group, and the beam reduction lens group cover is arranged at the laser emission end.

[0018] By adopting the above technical solution, the present solution can adjust the diameter of the laser emitted by the laser through the beam reduction lens group, so that it can be adjusted according to the requirements of different types of gas spectrum detection.

[0019] Preferably, the head end cavity mirror and the end cavity mirror are symmetrically tilted and arranged on the reflector fixing frame, and the head end cavity mirror and the end cavity mirror are symmetrically tilted toward the folding reflector, and a rotating shaft is provided at the bottom of the head end cavity mirror and the end cavity mirror, and the head end cavity mirror and the end cavity mirror are rotatably connected to the reflector fixing frame through the rotating shaft, and a rotation damping member is provided on the top of the reflector fixing frame, and the rotation damping member is rotationally damped with the outer arc surface of the rotating shaft, and the rotation structure of the reflector fixing frame and the folding reflector on the other side is the same as the rotation structure of the head end cavity mirror, the end cavity mirror and the reflector fixing frame, and the head end cavity mirror is provided with a light hole near the edge.

[0020] By adopting the above technical solution, this solution can adjust the orientation of the head-end cavity mirror and the end cavity mirror during use through the structure of the rotating shaft and the rotating damping member. At the same time, the structure of the rotating damping member can ensure that after the orientation angle adjustment of the head-end cavity mirror and the end cavity mirror is completed, the head-end cavity mirror and the end cavity mirror will not rotate accidentally during actual use, thereby ensuring stable laser reflection.

[0021] Preferably, a concave arc surface is provided on the side of the signal collecting reflector, which faces the direction of the Raman probe. The focus of the Raman probe coincides with the focus of the signal collecting reflector. The signal collecting reflector is arranged on the side of the Raman gas cell body and is perpendicular to the propagation path of the laser beam. Its focus is located near the center of the folding reflector to ensure that the side scattered Raman signal can be efficiently collected.

[0022] By adopting the above technical solution, this solution can ensure that the detection point is located at the position with the maximum detection laser intensity during spectral detection by aligning the focus of the Raman probe with the signal collection mirror, so that the refraction effect of the gas on the laser is most obvious, which facilitates the detection of gas by this device.

[0023] Preferably, a sealing member is provided on the inner side wall of the Raman gas cell body.

[0024] By adopting the above technical solution, the present solution can effectively improve the sealing performance of the Raman gas cell body of the present device through the sealing member, thereby improving the stability of the present device during the gas detection process.

[0025] In summary, the present invention has at least one of the following beneficial effects:

[0026] The utility model adopts a folded multiple-reflection gas chamber design, combined with an optimized mechanical structure, optical path design and signal collection scheme, which not only effectively reduces the volume of the Raman gas cell, but also significantly improves the number of laser reflections and measurement sensitivity, meeting the needs of high-precision and portable detection of multi-component gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a front view of an embodiment of the utility model based on a folded multiple reflection gas chamber enhanced gas Raman spectroscopy measurement device;

[0029] Figure 2 This is the light spot distribution diagram of the first-end cavity mirror of the utility model;

[0030] Figure 3 This is the light spot distribution diagram of the end cavity mirror of the utility model;

[0031] Figure numerals: 01, laser; 02, laser beam reduction device; 03, head end cavity mirror; 04, folding reflector; 05, end cavity mirror; 06, reflector fixing bracket; 07, signal collection reflector; 08, Raman probe; 09, spectrometer; 10, Raman gas cell body. DETAILED DESCRIPTION

[0032] The following is combined with Figure 1-3 The utility model is described in further detail.

[0033] Example 1, as Figure 1-Figure 3 As shown, in order to solve the existing problems, in this embodiment, the utility model discloses a gas Raman spectroscopy measurement device based on a folded multiple reflection gas chamber, including a laser 01 and a Raman gas cell body 10. The emitting end of the laser 01 is provided with a laser beam reduction device 02. Two reflector fixing frames 06 are connected to the Raman gas cell body 10. The reflector fixing frame 06 on one side is rotatably connected to the folding reflector 04, and the reflector fixing frame 06 on the other side is connected to the head end cavity mirror 03 and the end cavity mirror 05. A Raman probe 08 is connected to one side of the Raman gas cell body 10, and a signal collection reflector 07 is provided in the Raman gas cell body 10.

[0034] The emitting end of the Raman probe 08 faces the signal collecting reflector 07 , and one side of the emitting end of the Raman probe 08 is communicatively connected to a spectrometer 09 .

[0035] The Raman probe 08 includes a laser emitter and a laser receiver. Both the laser emitter and the laser receiver face the signal collecting reflector 07 . The laser emitter and the laser receiver are connected to the spectrometer 09 via a cable.

[0036] The laser beam reduction device 02 includes a beam reduction lens group, and the beam reduction lens group is covered at the emission end of the laser 01.

[0037] The head-end cavity mirror 03 and the end cavity mirror 05 are symmetrically tilted and arranged on the reflector fixing frame 06, and the head-end cavity mirror 03 and the end cavity mirror 05 are symmetrically tilted toward the folding reflector 04. A rotating shaft is provided at the bottom of the head-end cavity mirror 03 and the end cavity mirror 05, and the head-end cavity mirror 03 and the end cavity mirror 05 are rotatably connected to the reflector fixing frame 06 through the rotating shaft. A rotation damping member is provided on the top of the reflector fixing frame 06, and the rotation damping member is rotationally damped with the outer arc surface of the rotating shaft. The rotation structure of the reflector fixing frame 06 and the folding reflector 04 on the other side is the same as the rotation structure of the head-end cavity mirror 03, the end cavity mirror 05 and the reflector fixing frame 06.

[0038] The side of the signal collecting reflector 07 is provided with a concave arc surface, which faces the direction of the Raman probe 08. The focus of the Raman probe 08 coincides with the focus of the signal collecting reflector 07. The inner wall of the Raman gas cell body 10 is provided with a seal.

[0039] The specific working principle is: this device can effectively improve the detection accuracy of unknown gases. The head cavity mirror, folding reflector and end cavity mirror are all fixed at a certain angle, so that the light beam can be reflected back and forth multiple times between the three reflectors, and the light beam convergence center of the head cavity mirror and the light beam convergence center of the end cavity mirror are close but do not overlap; the signal collection adopts a lateral collection method, and a signal collection reflector is provided in the direction perpendicular to the laser beam to collect the diffused light signal. The Raman probe is fixed at the other end of the signal collection reflector to collect the signal and transmit the signal to the spectrometer. The folded multiple reflection gas chamber proposed in this utility model increases the number of laser reflections while effectively reducing the volume of the Raman gas pool, making it easy to install and carry. The laser is reflected multiple times in the cavity and converges at the center of the folding reflector, which greatly improves the laser intensity at this position. The detection sensitivity of multi-component gas Raman spectroscopy can reach the ppm level.

[0040] Example 2, as Figure 1-Figure 3 As shown, in order to solve the existing problems, based on the same concept as the above-mentioned embodiment 1, the present embodiment proposes the following implementation measures based on the folded multiple reflection gas chamber enhanced gas Raman spectroscopy measurement device:

[0041] The head-end cavity mirror 03 and the end cavity mirror 05 are spherical mirrors with a focal length of 50 mm, and the folding reflector is a plane reflector; the relative positions and angles of the head-end cavity mirror 03, the folding reflector 04 and the end cavity mirror 05 are obtained by the following method: the head-end cavity mirror 03 and the end cavity mirror 05 are placed opposite each other with a distance of 200 mm, and the folding reflector is located at the center of the head-end cavity mirror 03 and the end cavity mirror 05, and the head-end cavity mirror 03 is rotated 0.009° clockwise to achieve cavity mirror center deviation; the end cavity mirror 05 is rotated 165° around the center of the cavity so that the two cavity mirrors are located on the same side of the cavity and at a close distance; the folding reflector 04 is rotated 8° counterclockwise so that the incident light can be reflected multiple times between the head-end cavity mirror and the end cavity mirror.

[0042] A light-through hole is provided at the edge of the head-end cavity mirror 03;

[0043] In a specific implementation, the light hole is a circular light hole with a diameter of 2 mm. The distance between the light hole and the center of the head cavity mirror 03 is 10.5 mm. The laser is emitted by the laser 01, and after being reduced by the laser beam reduction device 02, it is emitted into the cavity through the light hole at a certain angle, so that the laser is reflected multiple times between the head cavity mirror 03, the folding reflector 04 and the end cavity mirror 05. The total number of reflections of the laser between the head cavity mirror 03 and the end cavity mirror 05 is 98 times. The spot distribution of the laser on the head cavity mirror 03 is as follows: Figure 2 As shown, the light spot distribution on the end cavity mirror 05 is as follows Figure 3 shown.

[0044] The laser wavelength is 532nm;

[0045] The head end cavity mirror 03, folding reflector 04, end cavity mirror 05, and signal collecting reflector 07 are fixed to the reflector fixing frame 06 by glue or screws, and the reflector fixing frame 06 is fixed to the Raman gas cell body 10 by sealing rings and screws.

[0046] The signal collecting reflector 07 is arranged on the side of the Raman gas cell body 10 and is perpendicular to the propagation path of the laser beam;

[0047] The focal length of the signal collecting reflector 07 is 20;

[0048] In a specific implementation, the focus of the signal collecting reflector 07 is located near the center of the folding reflector to ensure that the side scattered Raman signal can be collected efficiently.

[0049] The Raman probe 08 is fixed on the other side of the Raman gas cell body;

[0050] During specific implementation, the Raman probe 08 is located opposite to the signal collecting reflector, and the focus of the Raman probe coincides with the focus of the signal collecting reflector to maximize the reception of the collected Raman signal.

[0051] Through the above embodiment, the accuracy of spectral detection of unknown gas raw materials inside the Raman gas cell body 10 can be effectively improved. When the focal length of the signal collection reflector 07 is 20, the focusing effect of the detection laser is most concentrated, so that the intensity of the detection laser at the focal position is maximized, which facilitates gas detection.

[0052] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell, comprising a laser (01) and a Raman gas cell body (10), characterized in that: The laser (01) emission end is provided with a laser beam reduction device (02), and two reflector fixing frames (06) are connected inside the Raman gas cell body (10), one side reflector fixing frame (06) is rotatably connected to a folding reflector (04), and the other side reflector fixing frame (06) is connected to a head end cavity mirror (03) and a terminal cavity mirror (05), one side of the Raman gas cell body (10) is connected to a Raman probe (08), and a signal collecting reflector (07) is provided inside the Raman gas cell body (10).

2. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: The emitting end of the Raman probe (08) faces the signal collecting reflector (07), and one side of the emitting end of the Raman probe (08) is communicatively connected to a spectrometer (09).

3. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 2, characterized in that: The Raman probe (08) includes a laser transmitter and a laser receiver, both of which are oriented toward the signal collecting reflector (07), and the laser transmitter and the laser receiver are communicatively connected to the spectrometer (09) via a cable.

4. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: The laser beam reduction device (02) comprises a beam reduction lens group, and the beam reduction lens group cover is arranged at the emission end of the laser (01).

5. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: The head end cavity mirror (03) and the end cavity mirror (05) are symmetrically tilted and arranged on the reflector fixing frame (06); the head end cavity mirror (03) and the end cavity mirror (05) are symmetrically tilted toward the folding reflector (04); a rotating shaft is provided at the bottom of the head end cavity mirror (03) and the end cavity mirror (05); the head end cavity mirror (03) and the end cavity mirror (05) are rotationally connected to the reflector fixing frame (06) via the rotating shaft; a rotation damping member is provided at the top of the reflector fixing frame (06); the rotation damping member is rotationally damped and connected to the outer arc surface of the rotating shaft; the rotation structure of the reflector fixing frame (06) and the folding reflector (04) on the other side is the same as the rotation structure of the head end cavity mirror (03), the end cavity mirror (05) and the reflector fixing frame (06).

6. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: A concave arc surface is provided on the side of the signal collecting reflector (07), and the concave arc surface faces the direction of the Raman probe (08), and the focus of the Raman probe (08) coincides with the focus of the signal collecting reflector (07).

7. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: A concave arc surface is provided on one side of the head end cavity mirror (03) and the end cavity mirror (05) facing the folding reflector (04), and the focal points of the arc surfaces of the head end cavity mirror (03) and the end cavity mirror (05) coincide with each other.

8. The gas Raman spectroscopy measurement device based on a folded multiple reflection gas cell according to claim 1, characterized in that: The inner side wall of the Raman gas cell body (10) is provided with a sealing member.

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