Gas Raman enhancement pool

Abstract

The embodiment of the invention provides a gas Raman enhancement pool. The gas Raman enhancement pool comprises an incident mirror, a reflecting mirror and a shell assembly, the shell assembly is provided with an air inlet and a light through hole, the incident mirror is arranged at the end, provided with the light through hole, of the shell assembly, and the reflecting mirror is arranged at the end, away from the light through hole, of the shell assembly. The incident mirror and the reflecting mirror are located in the shell assembly so as to form an optical stabilization cavity in a spaced mode, the light through hole is used for allowing laser to enter the optical stabilization cavity, and the gas inlet is communicated with the optical stabilization cavity so as to allow sample gas to enter the optical stabilization cavity. The optical stabilization cavity is used for enabling laser to be reflected at least once between the incident mirror and the reflecting mirror, and the gas Raman enhancement pool forms a light path from the light through hole, the optical stabilization cavity to the light through hole, so that Raman scattering light generated when the laser passes through the sample gas is propagated along the light path. The gas Raman enhancement pool provided by the embodiment of the invention is simple in structure.

Description

Technical Field

[0001] The present application relates to the technical field of Raman spectroscopy analysis, and in particular to a gas Raman enhancement cell. Background Art

[0002] Raman spectroscopy analysis technology has the characteristics of fast, high efficiency, non-destructive samples, and simultaneous analysis of multi-component samples. It has been widely used in medical, petrochemical, environmental science, materials, molecular identification and other fields.

[0003] However, the low Raman scattering signal intensity and susceptibility to interference from ambient natural light and fluorescence have greatly limited the wider application of Raman spectroscopy analysis technology. The Raman scattering signal intensity is proportional to the excitation light intensity, and increasing the excitation light power can increase the Raman scattering signal intensity.

[0004] However, the structure of the gas Raman enhancement cell in the related art is relatively complex. Summary of the invention

[0005] In view of this, the main purpose of the embodiments of the present application is to provide a gas Raman enhancement cell with a simple structure.

[0006] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0007] The present application embodiment provides a gas Raman enhancement cell, comprising:

[0008] Entrance mirror;

[0009] Reflector;

[0010] A housing component, wherein the housing component has an air inlet and a light through hole, the incident mirror is arranged at one end of the housing component having the light through hole, and the reflector is arranged at one end of the housing component away from the light through hole; the incident mirror and the reflector are located in the housing component to form an optically stable cavity at intervals, the light through hole is used for laser to enter the optically stable cavity, and the air inlet is communicated with the optically stable cavity to allow sample gas to enter the optically stable cavity;

[0011] The optical stabilization cavity is used for allowing the laser to be reflected at least once between the incident mirror and the reflector, and the gas Raman enhancement cell forms an optical path from the light through hole, the optical stabilization cavity to the light through hole, so that the Raman scattered light generated by the laser passing through the sample gas propagates along the optical path.

[0012] In one embodiment, at least one of a side of the incident mirror close to the optically stable cavity and a side of the reflective mirror close to the optically stable cavity is coated with a dielectric film.

[0013] In one embodiment, the incident mirror has a light-transmitting hole, the dielectric film avoids the light-transmitting hole, and the light-transmitting hole is connected to the light-through hole to allow the laser to enter the optical stabilization cavity.

[0014] In one embodiment, the shell assembly includes a shell, a first fixing ring and a second fixing ring, the first fixing ring and the second fixing ring are arranged at opposite ends of the shell, the incident mirror is fixed in the first fixing ring, and the reflecting mirror is fixed in the second fixing ring.

[0015] In one embodiment, the shell assembly includes a first blind flange, a second blind flange, a first internal welding flange and a second internal welding flange, the opposite ends of the first internal welding flange are respectively connected to the shell and the first fixing ring, the end of the first fixing ring facing away from the first internal welding flange is connected to the first blind flange, the opposite ends of the second internal welding flange are respectively connected to the shell and the second fixing ring, and the end of the second fixing ring facing away from the second internal welding flange is connected to the second blind flange.

[0016] In one embodiment, the first blind flange has the gas inlet, and the gas inlet is used to supply the sample gas to enter the optical stabilization cavity; and / or,

[0017] The first blind plate flange has the light-through hole, the incident mirror has a light-transmitting hole, and the light-through hole is connected with the light-transmitting hole to allow the laser to enter the optical stabilization cavity.

[0018] In one embodiment, the gas Raman enhancement cell comprises a window, and the window is arranged at the light-through hole; and / or,

[0019] At least one of the incident mirror and the reflecting mirror is a concave mirror.

[0020] In one embodiment, the material type of the shell is quartz; and / or,

[0021] The housing is transparent; and / or

[0022] The shell is cylindrical.

[0023] In one embodiment, at least one of the incident mirror and the reflector is made of K7 glass; and / or,

[0024] The gas Raman enhancement cell comprises an adjustment bracket, and the shell assembly is detachably arranged on the adjustment bracket.

[0025] In one embodiment, the gas Raman enhancement cell includes a light source assembly, and the light source assembly is arranged at the light through hole so that the laser generated by the light source assembly is incident on the optical stabilization cavity; and / or,

[0026] The gas Raman enhancement cell comprises a laser protection cover having a laser passage, wherein the laser protection cover is arranged between the light source assembly and the light through hole so that the laser passes through the laser passage and enters the optical stabilization cavity.

[0027] The embodiment of the present application provides a gas Raman enhancement cell, including an incident mirror, a reflector, and a shell assembly. The shell assembly has an air inlet and a light hole, the incident mirror is arranged at one end of the shell assembly having the light hole, and the reflector is arranged at one end of the shell assembly away from the light hole; the incident mirror and the reflector are located in the shell assembly to form an optically stable cavity with intervals, the light hole is used for laser to enter the optically stable cavity, and the air inlet is connected to the optically stable cavity to allow sample gas to enter the optically stable cavity. The optically stable cavity is used for the laser to be reflected at least once between the incident mirror and the reflector, and the gas Raman enhancement cell forms an optical path from the light hole, the optically stable cavity to the light hole, so that the Raman scattered light generated by the laser passing through the sample gas propagates along the optical path. Therefore, by setting a light hole for the laser and Raman scattered light to pass through, on the one hand, the number of optical elements and interfaces is reduced, and the structure of the gas Raman enhancement cell is simplified to a certain extent. In the assembly of the gas Raman enhancement cell, there is no need to accurately align multiple different light path entrances and exits, which reduces the requirements for process accuracy and reduces the risk of failure caused by improper component connection and light path adjustment, making the light path adjustment simpler. On the other hand, while reflecting the laser, the reflector also focuses the Raman scattered light in the direction of the light hole and emits it from the light hole, thereby improving the collection efficiency of the Raman scattered light. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of a gas Raman enhancement cell according to an embodiment of the present application;

[0029] Figure 2 This is an exploded diagram of a gas Raman enhancement cell according to another embodiment of the present application;

[0030] Figure 3 for Figure 1 Cross-sectional view of the gas Raman enhancement cell;

[0031] Figure 4 The original Raman spectra of oxygen and nitrogen measured by the gas Raman enhancement cell in one embodiment of the present application.

[0032] Description of Reference Numerals

[0033] 10. Incident mirror; 10a. Light-transmitting hole; 20. Reflector; 30. Shell assembly; 30a. Optical stabilization cavity; 31. Shell; 32. First fixing ring; 33. Second fixing ring; 34. First blind flange; 34a. Air inlet; 34b. Light-transmitting hole; 35. Second blind flange; 35a. Air outlet; 36. First internal welding flange; 37. Second internal welding flange; 38. First cavity retaining flange; 39. Second cavity retaining flange; 40. Window; 41. Cavity retaining rod. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and are therefore only used as examples, and the protection scope of the present application cannot be limited by this. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0037] For gas samples, the main ways to increase the excitation light power include: using high-power lasers to directly enhance the Raman scattering signal; using a cavity-enhanced Raman signal gas pool to make the excitation light reflect multiple times in the gas pool to locally enhance the Raman scattering signal. Since high-power lasers have the disadvantages of being large in size, expensive, and easy to damage optical components, cavity enhancement is often used to increase the excitation light power.

[0038] The principle of the gas Raman enhancement cell is to use two mirrors to make the laser reflect back and forth between them multiple times, increasing the effective propagation path of the light to meet specific optical measurement or experimental requirements. The specific principle is as follows:

[0039] (1) Initial incidence and first reflection of laser: A laser beam is shot into the gas Raman enhancement cell from a specific direction and first reaches one of the concave mirrors (called the incident mirror). Due to the characteristics of the concave mirror, the laser will be reflected to the other concave mirror (called the reflector). This is the first reflection of the laser in the optical cell, and the direction and angle of reflection are determined by factors such as the curvature radius of the concave mirror and the incident angle of the laser.

[0040] (2) Multiple reflection process: After the laser reaches the reflector, it will be reflected back to the incident mirror, and so on. With each reflection, the laser will propagate along a specific path between the two concave mirrors. As long as the position and angle of the two concave mirrors are set properly, the laser can stably reflect back and forth between them multiple times.

[0041] (3) Increase the optical path: Through this multiple reflection method, the path length of the laser in the optical cell is much longer than the physical length of the optical cell itself, thereby effectively increasing the optical path. For example, originally the laser may only be able to propagate within a short distance, but in the gas Raman enhancement cell, the laser can be reflected dozens or even hundreds of times, increasing the optical path to several meters or even longer, which can greatly improve the signal level for spectral detection of gas concentration.

[0042] (4) Enhanced light intensity: By focusing the laser multiple times at a certain point or area in the cavity, the light intensity at that point or area is greatly increased, thereby improving the signal level.

[0043] (5) Energy retention and loss: Ideally, the reflectivity of the concave reflector is very high, and the laser energy loss during the reflection process is small, so it can maintain a high intensity. However, in reality, due to factors such as the surface quality of the reflector and the absorption of the material, the laser will lose a certain amount of energy each time it is reflected.

[0044] Before using the gas Raman enhancement cell, the optical path needs to be strictly adjusted. The position and angle of the incident laser, two concave mirrors, and the scattered light collection end lens all affect the Raman signal.

[0045] However, the structure of the gas Raman enhancement cell in the related art is relatively complex, and there is a problem of difficulty in adjusting the optical path. For example, the cavity of the gas Raman enhancement cell in the related art is made of stainless steel, and the optical path in the cell cannot be seen when adjusting the optical path. For another example, the gas Raman enhancement cell in the related art is mostly hexahedral in appearance, and the spherical concave reflector is fixed in the cell through a mirror frame, and the concave mirror needs to be aligned for the optical path.

[0046] An embodiment of the present application provides a gas Raman enhancement cell, see Figure 1 , Figure 2 and Figure 3 The gas Raman enhancement cell includes an incident mirror 10 , a reflecting mirror 20 and a shell assembly 30 .

[0047] The shell assembly 30 has an air inlet 34a and a light hole 34b. The incident mirror 10 is arranged at one end of the shell assembly 30 having the light hole 34b, and the reflector 20 is arranged at the end of the shell assembly 30 away from the light hole 34b. The incident mirror 10 and the reflector 20 are located in the shell assembly 30 to form an optically stable cavity 30a at intervals. The light hole 34b is used for allowing laser light to enter the optically stable cavity 30a. The air inlet 34a is connected to the optically stable cavity 30a to supply sample gas to enter the optically stable cavity 30a.

[0048] The optical stabilization cavity 30a is used to allow the laser to be reflected at least once between the incident mirror 10 and the reflector 20, and the gas Raman enhancement cell forms an optical path from the light hole 34b, the optical stabilization cavity 30a to the light hole 34b, so that the Raman scattered light generated by the laser passing through the sample gas propagates along the optical path.

[0049] Specifically, the incident mirror 10 refers to a component located at the laser entrance of the optical stabilization cavity 30 a and capable of receiving the laser reflected by the reflection mirror 20 .

[0050] The incident mirror 10 is arranged opposite to the reflecting mirror 20 , and is used to receive the laser light and reflect the laser light to the components of the incident mirror 10 .

[0051] The material types of the incident mirror 10 and the reflective mirror 20 are not limited.

[0052] Exemplarily, at least one of the incident mirror 10 and the reflector 20 is made of K7 glass, thereby reducing the energy loss of the laser on the incident mirror 10 and / or the reflector 20 .

[0053] Specifically, only the incident mirror 10 may be made of K7 glass, only the reflecting mirror 20 may be made of K7 glass, or both the incident mirror 10 and the reflecting mirror 20 may be made of K7 glass.

[0054] The structural types of the incident mirror 10 and the reflective mirror 20 are not limited.

[0055] Exemplarily, at least one of the incident mirror 10 and the reflector 20 is a concave mirror. Thus, the energy density of the laser in the vicinity of the sample gas can be increased, so that Raman scattering can be more effectively stimulated when the laser interacts with the sample gas.

[0056] Specifically, only the incident mirror 10 may be a concave mirror, only the reflecting mirror 20 may be a concave mirror, or both the incident mirror 10 and the reflecting mirror 20 may be concave mirrors.

[0057] The laser is reflected at least once between the incident mirror 10 and the reflecting mirror 20, thereby increasing the interaction time and number of the laser and the sample gas, thereby enhancing the Raman scattering signal.

[0058] The housing assembly 30 refers to the structural support component of the gas Raman enhancement cell.

[0059] The gas inlet 34a refers to an inlet through which the sample gas enters the optical stabilization chamber 30a.

[0060] The light-through hole 34b is an entrance for laser light to enter the optical stabilization cavity 30a.

[0061] The optically stable cavity 30a refers to a space formed by the incident mirror 10 and the reflective mirror 20 in the housing assembly 30. The laser is reflected in the optically stable cavity 30a and interacts with the sample gas to generate Raman scattered light.

[0062] The laser light may be reflected only once or multiple times between the incident mirror 10 and the reflecting mirror 20 .

[0063] It should be noted that the laser enters the optically stable cavity 30a along the optical path from the light through hole 34b to the optically stable cavity 30a, and is reflected in the optically stable cavity 30a, interacting with the sample gas in the optically stable cavity 30a to generate Raman scattered light. The Raman scattered light is emitted from the light through hole 34b along the optical path from the optically stable cavity 30a to the light through hole 34b.

[0064] The gas Raman enhancement cell provided in the embodiment of the present application includes an incident mirror 10, a reflector 20 and a housing assembly 30. The housing assembly 30 has an air inlet 34a and a light through hole 34b. The incident mirror 10 is arranged at one end of the housing assembly 30 having the light through hole 34b, and the reflector 20 is arranged at one end of the housing assembly 30 away from the light through hole 34b. The incident mirror 10 and the reflector 20 are located in the housing assembly 30 to form an optically stable cavity 30a at intervals. The light through hole 34b is used for laser to enter the optically stable cavity 30a. The air inlet 34a is connected to the optically stable cavity 30a to allow sample gas to enter the optically stable cavity 30a. The optically stable cavity 30a is used for the laser to be reflected at least once between the incident mirror 10 and the reflector 20. The gas Raman enhancement cell forms an optical path from the light through hole 34b, the optically stable cavity 30a to the light through hole 34b, so that the Raman scattered light generated by the laser passing through the sample gas propagates along the optical path. Thus, by providing the light-through hole 34b for the laser and Raman scattered light to pass through, on the one hand, the number of optical elements and interfaces is reduced, and the structure of the gas Raman enhancement cell is simplified to a certain extent. In the assembly of the gas Raman enhancement cell, there is no need to accurately align multiple different light path entrances and exits, which reduces the requirements for process accuracy, reduces the risk of failure caused by improper component connection and light path adjustment, and makes the light path adjustment simpler. On the other hand, while reflecting the laser, the reflector 20 also focuses the Raman scattered light in the direction of the light-through hole 34b and emits it from the light-through hole 34b, thereby improving the collection efficiency of the Raman scattered light.

[0065] In one embodiment, at least one of the side of the incident mirror 10 close to the optical stabilization cavity 30a and the side of the reflector 20 close to the optical stabilization cavity 30a is coated with a dielectric film. As a result, when the laser is reflected on the incident mirror 10 and the reflector 20, more laser energy can be reflected back into the optical stabilization cavity 30a, thereby improving the reflectivity of the laser and reducing the energy loss of the laser during the reflection process.

[0066] Specifically, only the side of the incident mirror 10 close to the optical stabilization cavity 30a may be coated with a dielectric film, or only the side of the reflector 20 close to the optical stabilization cavity 30a may be coated with a dielectric film, or both the side of the incident mirror 10 close to the optical stabilization cavity 30a and the side of the reflector 20 close to the optical stabilization cavity 30a may be coated with a dielectric film.

[0067] The type of dielectric film is not limited, as long as it can reduce the energy loss of the laser during the reflection process.

[0068] In one embodiment, please refer to Figure 2The incident mirror 10 has a light-transmitting hole 10a, the dielectric film avoids the light-transmitting hole 10a, and the light-transmitting hole 10a is connected with the light-through hole 34b, so that the laser can enter the optically stable cavity 30a. In this way, multiple reflections and scattering of the laser during the incident process are avoided, and the energy loss of the laser during the process of entering the optically stable cavity 30a through the incident mirror 10 is reduced.

[0069] Specifically, the light-transmitting hole 10 a refers to a hole opened on the incident mirror 10 for allowing laser light to pass through.

[0070] The shape and size of the light-transmitting hole 10a are not limited as long as the laser can pass through.

[0071] The dielectric film avoids the light-transmitting hole 10 a means that the dielectric film does not cover the light-transmitting hole 10 a , that is, there is no dielectric film at the light-transmitting hole 10 a .

[0072] In one embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The housing assembly 30 includes a housing 31, a first fixing ring 32 and a second fixing ring 33. The first fixing ring 32 and the second fixing ring 33 are arranged at opposite ends of the housing 31. The incident mirror 10 is fixed in the first fixing ring 32, and the reflector 20 is fixed in the second fixing ring 33. Therefore, on the one hand, the incident mirror 10 and the reflector 20 are fixed in the first fixing ring 32 and the second fixing ring 33 respectively, and then the first fixing ring 32 and the second fixing ring 33 are respectively installed at the two ends of the housing 31, which greatly simplifies the assembly process of the gas Raman enhancement cell. On the other hand, the first fixing ring 32 and the second fixing ring 33 can effectively limit the displacement and rotation of the incident mirror 10 and the reflector 20, so that the incident mirror 10 and the reflector 20 can maintain the stability of their relative position and angle during the operation of the equipment, thereby improving the accuracy of detection.

[0073] Specifically, the first fixing ring 32 refers to an annular component used to fix the incident mirror 10. The first fixing ring 32 is connected to the shell 31 to provide an installation position and stable support for the incident mirror 10, so that the position of the incident mirror 10 in the shell 31 is relatively fixed, so that the laser can accurately pass through the incident mirror 10 into the optical stabilization cavity 30a.

[0074] The second fixing ring 33 refers to an annular component for fixing the reflector 20. The second fixing ring 33 is arranged at an end of the shell 31 opposite to the first fixing ring 32 to firmly install the reflector 20 at a predetermined position in the shell 31, so that the reflector 20 is opposite to the incident mirror 10 and the position is stable, so that the laser can be stably reflected between the two.

[0075] The connection method between the first fixing ring 32 and the second fixing ring 33 and the housing 31 is not limited.

[0076] For example, the first fixing ring 32 and the second fixing ring 33 are connected to the housing 31 by bolts.

[0077] The material type of the first fixing ring 32 is not limited.

[0078] For example, the material type of the first fixing ring 32 is aluminum alloy or stainless steel.

[0079] The material type of the second fixing ring 33 is not limited.

[0080] For example, the material type of the second fixing ring 33 is aluminum alloy or stainless steel.

[0081] The material type of the housing 31 is not limited.

[0082] For example, the material type of the housing 31 is quartz.

[0083] In one embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The housing assembly 30 includes a first blind flange 34, a second blind flange 35, a first internal welding flange 36 and a second internal welding flange 37. The opposite ends of the first internal welding flange 36 are respectively connected to the housing 31 and the first fixing ring 32. The end of the first fixing ring 32 away from the first internal welding flange 36 is connected to the first blind flange 34. The opposite ends of the second internal welding flange 37 are respectively connected to the housing 31 and the second fixing ring 33. The end of the second fixing ring 33 away from the second internal welding flange 37 is connected to the second blind flange 35. In this way, the stability of the incident mirror 10 and the reflector 20 during operation can be further improved, thereby improving the detection accuracy.

[0084] Specifically, the first blind flange 34 and the first internal welding flange 36 are components for fixing the first fixing ring 32. The first blind flange 34 and the first internal welding flange 36 are arranged at intervals, and the first fixing ring 32 is arranged in the interval between the first blind flange 34 and the first internal welding flange 36. The first internal welding flange 36 is fixed to the housing 31 to fix the incident mirror 10.

[0085] The connection method of the first blind flange 34, the first internal welding flange 36 and the first fixing ring 32 is not limited.

[0086] For example, the first blind flange 34 , the first internal welding flange 36 , and the first fixing ring 32 are fastened and connected by bolts.

[0087] The second blind flange 35 and the second internal welding flange 37 are components for fixing the second fixing ring 33. The second blind flange 35 and the second internal welding flange 37 are arranged at intervals, and the second fixing ring 33 is arranged in the interval between the second blind flange 35 and the second internal welding flange 37. The second internal welding flange 37 is fixed to the housing 31 to fix the reflector 20.

[0088] The connection method of the second blind flange 35, the second internal welding flange 37 and the second fixing ring 33 is not limited.

[0089] For example, the second blind flange 35, the second internal welding flange 37 and the second fixing ring 33 are fastened and connected by bolts.

[0090] The material types of the first blind flange 34 and the second blind flange 35 are not limited.

[0091] For example, the material type of at least one of the first blind flange 34 and the second blind flange 35 is stainless steel.

[0092] The material types of the first internal welding flange 36 and the second internal welding flange 37 are not limited.

[0093] For example, the material type of at least one of the first internal welding flange 36 and the second internal welding flange 37 is stainless steel.

[0094] In a specific embodiment, the gas Raman enhancement cell includes a first sealing ring, which is disposed between the first blind flange 34 and the first internal welding flange 36. Thus, leakage of the sample gas can be prevented.

[0095] Specifically, the material type of the first sealing ring is not limited.

[0096] For example, the first sealing ring is an oxygen-free copper sealing ring.

[0097] In a specific embodiment, the gas Raman enhancement cell includes a second sealing ring, which is disposed between the second blind flange 35 and the second internal welding flange 37. Thus, leakage of the sample gas can be prevented.

[0098] Specifically, the material type of the second sealing ring is not limited.

[0099] For example, the second sealing ring is an oxygen-free copper sealing ring.

[0100] In one embodiment, please refer to Figure 1 The first blind flange 34 has a gas inlet 34a, and the gas inlet 34a is used to supply sample gas to enter the optical stabilization cavity 30a.

[0101] Specifically, the gas inlet 34 a is communicated with the optical stabilization chamber 30 a , and the sample gas enters the optical stabilization chamber 30 a through the gas inlet 34 a .

[0102] In one embodiment, please refer to Figure 1 The first blind flange 34 has a light hole 34b, and the incident mirror 10 has a light-transmitting hole 10a. The light hole 34b is connected with the light-transmitting hole 10a to allow the laser to enter the optically stable cavity 30a. Thus, the energy loss of the laser in the process of entering the optically stable cavity 30a can be reduced.

[0103] Specifically, the relative positions of the light-through hole 34 b and the light-transmitting hole 10 a are not limited, as long as the laser can pass through and enter the optical stabilization cavity 30 a .

[0104] For example, the light-through hole 34b and the light-transmitting hole 10a may be coaxially arranged, or may be eccentrically arranged relative to each other (ie, the light-through hole 34b and the light-transmitting hole 10a are not coaxial).

[0105] In one embodiment, please refer to Figure 2 The gas Raman enhancement cell includes a window 40, which is arranged at the light-through hole 34b, thereby preventing foreign impurities from entering the optical stabilization cavity 30a through the light-through hole 34b, thereby affecting the accuracy of detection.

[0106] Specifically, the window plate 40 refers to a component that is disposed at the light-through hole 34 b and can allow laser light to pass through.

[0107] The material type of the window sheet 40 is not limited.

[0108] For example, the window 40 is a sapphire window 40 .

[0109] The manner in which the window piece 40 is disposed at the light-through hole 34 b is not limited.

[0110] For example, the window plate 40 is installed at the light-through hole 34 b of the first blind flange 34 by electric welding.

[0111] In one embodiment, the housing 31 is transparent. Therefore, in the case of the gas Raman enhancement cell, the number, size and shape of the light spots formed by the laser light path in the gas Raman enhancement cell on the surface of the incident mirror 10 and the surface of the reflector 20 can be clearly seen, so that the internal light path state of the gas Raman enhancement cell can be clearly seen when adjusting the light path, thereby adaptively adjusting the gas Raman enhancement cell.

[0112] In one embodiment, the housing 31 is cylindrical. Therefore, the incident mirror 10 and the reflector 20 are arranged at two ends of the cylindrical housing 31, which simplifies the adjustment steps of the incident mirror 10 and the reflector 20.

[0113] The shell assembly 30 of the gas Raman enhancement cell in the related art is square, and the incident mirror 10 and the reflector 20 are fixed on the shell assembly 30 through a mirror frame, so the position and angle of the incident mirror 10 and the reflector 20 need to be precisely adjusted.

[0114] The shell assembly 30 of the gas Raman enhancement cell of the present application is cylindrical, and the incident mirror 10 and the reflector 20 can be conveniently installed on the circular planes at both ends thereof. Due to the shape characteristics of the cylinder, its axis of symmetry is relatively clear and stable. During the installation process, it is only necessary to ensure that the incident mirror 10 and the reflector 20 are basically parallel to each other along the axial direction of the cylinder, so that a stable optical reflection cavity can be preliminarily constructed. Compared with the square shell 31, which requires fine adjustment of the mirror frame in multiple plane dimensions and angular directions, the complexity and workload of adjustment are greatly reduced.

[0115] In one embodiment, the gas Raman enhancement cell includes an adjustment bracket, and the housing assembly 30 is detachably arranged on the adjustment bracket. Therefore, on the one hand, the position and angle of the housing assembly 30 can be conveniently changed by adjusting the bracket, thereby adjusting the optical path between the incident mirror 10 and the reflector 20, so that the laser can achieve a better reflection effect in the optical stabilization cavity 30a, reducing the debugging time and workload, and improving the debugging accuracy of the equipment. On the other hand, the position of the gas Raman enhancement cell relative to the signal processing system can be adjusted by adjusting the bracket, so that the signal processing system can collect the optical signal of the Raman scattered light, thereby improving the detection efficiency.

[0116] Specifically, the adjustment bracket includes an adjustment button. During the optical path adjustment process, the signal and noise of the nitrogen component in the air are measured in real time, and the optical path and light spot in the gas Raman enhancement cell are observed. The shell assembly 30 is adjusted in multiple directions through the adjustment button so that the Raman scattered light signal detected by the signal processor is in a better state.

[0117] The light spot refers to the light spot formed by the laser on the surfaces of the incident mirror 10 and the reflecting mirror 20 .

[0118] In one embodiment, the gas Raman enhancement cell includes a light source assembly, which is disposed at the light through hole 34b so that the laser generated by the light source assembly is incident on the optical stabilization cavity 30a. Thus, by disposing the light source assembly at the light through hole 34b, the transmission distance and intermediate links of the laser from the light source to the optical stabilization cavity 30a are reduced, so that the laser can be incident on the optical stabilization cavity 30a with higher efficiency.

[0119] In one embodiment, the gas Raman enhancement cell includes a laser protection cover having a laser path, and the laser protection cover is disposed between the light source assembly and the light through hole 34b, so that the laser passes through the laser path and enters the optical stabilization cavity 30a. Thus, through the laser protection cover, the laser can be transmitted in a relatively pure environment, maintaining its original energy concentration and propagation direction, so that the laser can efficiently interact with the sample gas, thereby obtaining Raman scattered light with better effect.

[0120] Specifically, the size of the cross section of the laser protection cover is not limited.

[0121] For example, the cross section of the laser protection cover is smaller than the cross section of the light through hole 34 b , thereby facilitating the laser to smoothly pass through the light through hole 34 b and enter the optical stabilization cavity 30 a .

[0122] In one embodiment, the pressure of the sample gas in the optical stabilization cavity 30a is greater than or equal to 0.1Mpa and less than or equal to 0.4Mpa. For example, the pressure of the sample gas in the optical stabilization cavity 30a is 0.1Mpa, 0.2Mpa, 0.3Mpa or 0.4Mpa. Maintaining the pressure of the sample gas in the optical stabilization cavity 30a within the above range can, on the one hand, allow the laser to fully interact with the sample gas to form a high-intensity Raman scattered light. On the other hand, it can prevent the structure of the gas Raman enhancement cell from being damaged by excessive pressure.

[0123] In one embodiment, the gas Raman enhancement cell further includes a first cavity retaining flange 38, a cavity retaining rod 41 and a second cavity retaining flange 39. The opposite ends of the first cavity retaining flange 38 are respectively connected to the shell 31 and the first internal welding flange 36, and the opposite ends of the second cavity retaining flange 39 are respectively connected to the shell 31 and the second internal welding flange 37. The first cavity retaining flange 38 has a first opening, and the second cavity retaining flange 39 has a second opening. The opposite ends of the cavity retaining rod 41 are respectively inserted into the first opening and the second opening. Thus, the frame structure formed by the first cavity retaining flange 38, the cavity retaining rod 41 and the second cavity retaining flange 39 provides additional support and reinforcement for the shell 31, thereby preventing the shell 31 from being deformed or broken, thereby ensuring the structural integrity and stability of the optical stabilization cavity 30a, so that the optical path of the laser in the optical stabilization cavity 30a is not affected, and the accuracy of gas Raman spectrum detection is maintained.

[0124] In one embodiment, the gas Raman enhancement cell further has an outlet 35a, and at least one of the inlet 34a and the outlet 35a is connected to a 1 / 8 British threaded vacuum pipe joint, and the sample gas enters the optical stabilization cavity 30a through the inlet 34a and then flows out from the outlet 35a. Therefore, by connecting the inlet 34a, the outlet 35a and the external air pipe through the 1 / 8 British threaded vacuum pipe joint, reliable sealing performance can be provided, thereby improving the accuracy of detection.

[0125] In one embodiment, please refer to Figure 4 , the laser power emitted by the light source component is 1000mw, the exposure time is 1s, and oxygen and nitrogen are measured through a gas Raman enhancement cell to obtain the original Raman spectrum.

[0126] In the description of the present application, the description with reference to the terms "in one embodiment", "in some embodiments", "in a specific embodiment", or "exemplary" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine different embodiments or examples described in the present application and the features of different embodiments or examples without contradiction.

[0127] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A gas Raman enhancement cell, characterized in that: include: Entrance mirror; Reflector; A housing component, wherein the housing component has an air inlet and a light through hole, the incident mirror is arranged at one end of the housing component having the light through hole, and the reflector is arranged at one end of the housing component away from the light through hole; the incident mirror and the reflector are located in the housing component to form an optically stable cavity at intervals, the light through hole is used for laser to enter the optically stable cavity, and the air inlet is communicated with the optically stable cavity to allow sample gas to enter the optically stable cavity; The optical stabilization cavity is used for allowing the laser to be reflected at least once between the incident mirror and the reflector, and the gas Raman enhancement cell forms an optical path from the light through hole, the optical stabilization cavity to the light through hole, so that the Raman scattered light generated by the laser passing through the sample gas propagates along the optical path.

2. The gas Raman enhancement cell according to claim 1, characterized in that: At least one of a side of the incident mirror close to the optically stable cavity and a side of the reflective mirror close to the optically stable cavity is coated with a dielectric film.

3. The gas Raman enhancement cell according to claim 2, characterized in that: The incident mirror has a light-transmitting hole, the dielectric film avoids the light-transmitting hole, and the light-transmitting hole is connected with the light-through hole to allow the laser to enter the optical stabilization cavity.

4. The gas Raman enhancement cell according to claim 1, characterized in that: The housing assembly comprises a housing, a first fixing ring and a second fixing ring, wherein the first fixing ring and the second fixing ring are arranged at opposite ends of the housing, the incident mirror is fixed in the first fixing ring, and the reflecting mirror is fixed in the second fixing ring.

5. The gas Raman enhancement cell according to claim 4, characterized in that: The shell assembly includes a first blind flange, a second blind flange, a first internal welding flange and a second internal welding flange, the opposite ends of the first internal welding flange are respectively connected to the shell and the first fixing ring, the end of the first fixing ring facing away from the first internal welding flange is connected to the first blind flange, the opposite ends of the second internal welding flange are respectively connected to the shell and the second fixing ring, and the end of the second fixing ring facing away from the second internal welding flange is connected to the second blind flange.

6. The gas Raman enhancement cell according to claim 5, characterized in that: The first blind flange has the gas inlet, and the gas inlet is used for supplying the sample gas into the optical stabilization cavity; and / or, The first blind plate flange has the light-through hole, the incident mirror has a light-transmitting hole, and the light-through hole is connected with the light-transmitting hole to allow the laser to enter the optical stabilization cavity.

7. The gas Raman enhancement cell according to any one of claims 1 to 6, characterized in that: The gas Raman enhancement cell comprises a window, and the window is arranged at the light-through hole; and / or, At least one of the incident mirror and the reflecting mirror is a concave mirror.

8. The gas Raman enhancement cell according to any one of claims 4 to 6, characterized in that: The material type of the shell is quartz; and / or, The housing is transparent; and / or The shell is cylindrical.

9. The gas Raman enhancement cell according to any one of claims 1 to 6, characterized in that: At least one of the incident mirror and the reflector is made of K7 glass; and / or, The gas Raman enhancement cell comprises an adjustment bracket, and the shell assembly is detachably arranged on the adjustment bracket.

10. The gas Raman enhancement cell according to any one of claims 1 to 6, characterized in that: The gas Raman enhancement cell comprises a light source assembly, and the light source assembly is arranged at the light through hole so that the laser generated by the light source assembly is incident into the optical stabilization cavity; and / or, The gas Raman enhancement cell comprises a laser protection cover having a laser passage, wherein the laser protection cover is arranged between the light source assembly and the light through hole so that the laser passes through the laser passage and enters the optical stabilization cavity.

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