Gas Raman signal detection system matched with receiving slit and use method

Abstract

The invention discloses a gas Raman signal detection system matched with a receiving slit. The system comprises a laser area and an imaging area, the imaging area comprises a Raman signal, one end of the Raman signal is received by a receiving slit of the spectrograph in the length direction of the receiving slit, the other end of the Raman signal is emitted from a reflection focus of the laser area, and during application, the imaging area of the Raman signal in the imaging area is parallel to the receiving slit of the spectrograph; a Raman signal is imaged on a receiving slit of the spectrometer through the lens and the light path, and is efficiently received by the receiving slit; the receiving slit is parallel to the direction of the Raman signal, so that the receiving range of the receiving slit for the Raman signal is large, and compared with the prior art that only the Raman signal within the focus range can be received, the receiving efficiency is greatly improved. Therefore, the receiving range of the Raman signal is relatively large, and the receiving efficiency is relatively high.

Description

Technical Field

[0001] The invention relates to a Raman signal detection system, belongs to the field of Raman gas detection, and in particular to a gas Raman signal detection system with a matching receiving slit and a use method thereof. Background Art

[0002] Raman spectroscopy is a powerful gas sensing method that can overcome the weaknesses of traditional non-spectral methods such as long detection time and poor repeatability, and can also make up for the defect that absorption spectroscopy cannot directly measure homonuclear diatomic molecules; at the same time, it can also use a single-frequency laser to perform qualitative and quantitative analysis on multi-component mixed gases, which is more convenient. However, in the detection process of Raman spectroscopy, due to the inherent weak Raman effect of the substance, and the fact that the Raman effect of gas is usually much lower than that of solids and liquids, there is a problem of low gas Raman signal intensity, which leads to certain limitations of gas Raman detection method.

[0003] A Chinese patent with application number 202022629335.3 and application date of November 13, 2020 discloses a Raman spectroscopy excitation enhancement module, in which the laser light emitted by the laser is reflected by the first reflector and the second reflector in turn, converged by the first lens and reflected by the third reflector, and then passes through the small hole of the first concave reflector and the first window piece in turn and focuses on a focus of the detection point, and then is reflected by the second concave reflector and focuses on another focus of the detection point. In this way, the laser light is reflected multiple times between the first concave reflector and the second concave reflector, and each reflection is focused on two focal points at the detection point. The interior of the chamber surrounded by the first window piece, the second window piece, the third window piece, and the fourth window piece contains the liquid or gas to be tested. In this way, the Raman signal generated by the laser excitation sample at the two focal points can be enhanced by 50-100 times. After the Raman signals at the two focal points are collected by the second lens, the Rayleigh scattering of the laser is filtered out by the filter, and the Raman light signal is concentrated at the slit of the spectrometer. Although this design achieves the effect of enhancing the intensity of the gas Raman signal by enhancing the laser intensity at the focal point, it still has the following defects: In this design, the width of the receiving slit of the spectrometer is small, and it can only receive Raman signals within the focal range, so the receiving range for Raman signals is small, which will result in low receiving efficiency of the receiving slit for Raman signals.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and problems of the prior art in that the receiving range of Raman signals is relatively small, and to provide a gas Raman signal detection system with a matching receiving slit having a larger receiving range of Raman signals.

[0006] To achieve the above objectives, the technical solution of the present invention is: A gas Raman signal detection system matching a receiving slit, the system comprising a laser area and an imaging area; The imaging area includes a Raman signal, one end of which is received by a receiving slit of a spectrometer along its length direction, and the other end of which is emitted from a reflection focus of a laser area.

[0007] The imaging area includes a collecting lens group, which includes a front lens, a rear lens and a Dove prism in the same plane. The angle between the Dove prism and the horizontal plane is a certain angle. The Dove prism is provided with a rear lens on the side close to the receiving slit, and the Dove prism is provided with a front lens on the side away from the receiving slit. The focus of the front lens coincides with the reflection focus of the reflecting lens group.

[0008] The laser zone includes a reflector group; The reflector group includes a first lens and a second lens which are symmetrical along the reflection focus, the focus of the first lens coincides with the reflection focus, the axis of the first lens is perpendicular to the axis of the front lens, and the first lens is provided with a first reflector and a laser emitter in a direction away from the reflection focus; the axis of the second lens is perpendicular to the axis of the front lens, and the second lens is provided with a second reflector in a direction away from the reflection focus; a concave mirror is provided at the reflection focus in a direction away from the front lens.

[0009] The angle between the Dove prism and the horizontal plane is forty-five degrees or one hundred and thirty-five degrees.

[0010] The focal length ratio of the front lens to the rear lens ranges from one-half to two times.

[0011] The distance from the concave mirror to the reflection focus is twice the focal length of the concave mirror.

[0012] The first reflector has a width dimension of one-half inch to two inches, and the second reflector has a width dimension of one-half inch to two inches.

[0013] The clear aperture of the Dove prism is ten to fifty millimeters, and the length of the receiving slit is two to eight millimeters.

[0014] The first reflector includes a first transverse surface and a first vertical surface, one end of the first vertical surface is perpendicularly connected to one end of the first transverse surface, and the angle between the first transverse surface and the vertical surface is forty-five degrees; the second reflector includes a second transverse surface and a second vertical surface, one end of the second vertical surface is perpendicularly connected to one end of the second transverse surface, and the angle between the second transverse surface and the vertical surface is forty-five degrees.

[0015] A method for using a gas Raman signal detection system with a matching receiving slit, characterized in that the method comprises the following steps: The first step: first make a large number of laser signals converge at the reflection focus multiple times; Step 2: The laser signal at the reflection focus reacts with the gas to be measured at the reflection focus to generate a Raman signal; Step 3: The imaging area of ​​the Raman signal in the imaging area is parallel to the receiving slit of the spectrometer. The Raman signal is imaged on the receiving slit of the spectrometer through the lens and the optical path and is received by the receiving slit.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In a gas Raman signal detection system and a method for using a matching receiving slit of the present invention, the system includes a laser area and an imaging area, the imaging area includes a Raman signal, one end of the Raman signal is received by the receiving slit of the spectrometer along its length direction, and the other end of the Raman signal is emitted from the reflection focus of the laser area. When used, the Raman signal is emitted from the reflection focus, and the Raman signal imaging area is changed to a direction parallel to the receiving slit of the spectrometer by a certain method, and is imaged on the receiving slit of the spectrometer through a lens and an optical path, and is efficiently received by the receiving slit. The advantages of the present invention also include: First point: In the prior art, the vertical receiving slit is aligned with the focus of the Raman signal, so the Raman signal can be received only within the focus range. Since the width of the receiving slit is only ten microns, the receiving range of the Raman signal is small. In the present invention, the receiving slit is aligned with the Raman signal parallel to it, and the length of the receiving slit is six millimeters, so the receiving range of the Raman signal is larger. The receiving range of the Raman signal is expanded from the focus to the length of the receiving slit, so the receiving efficiency of the Raman signal is higher. Second point: the Raman signal can be parallel to the shape of the receiving slit to expand the receiving range of the Raman signal by the receiving slit. The present invention includes but is not limited to making the optical path a vertical optical path to match the vertical receiving slit, or rotating the spectrometer to make the receiving slit horizontal to match the horizontal optical path, etc., and is not limited to the type and number of prisms. Third point: Since the present invention has a high efficiency in receiving Raman signals, when the content of the gas to be measured is low, the Raman signals generated by the gas to be measured can be collected, so the present invention can improve the limit of gas detection; Fourth point: In the prior art, although the detection limit of the reflective cavity based on this structure can reach the ppb level, there are problems such as complex system structure and large system volume; in the present invention, the detection limit can not only reach the ppb level, but also the system structure is simple and the system volume is small; Therefore, the present invention has a larger receiving range for Raman signals and a higher receiving efficiency.

[0017] 2. In a gas Raman signal detection system and a method for using a matching receiving slit of the present invention, the system includes a collecting mirror group and a reflecting mirror group, the collecting mirror group includes a front lens, a Dove prism and a rear lens arranged in sequence, the Dove prism has a certain angle with the horizontal plane, the focus of the rear lens is provided with a receiving slit of a spectrometer, the focus of the front lens is the reflection focus of the reflecting mirror group, when used, the laser signal reacts with the gas to be measured to generate a horizontally distributed Raman signal, and then the horizontally distributed Raman signal is reflected once in the Dove prism and becomes a vertically distributed Raman signal, and then the vertically distributed Raman signal is imaged in the receiving slit of the spectrometer to be received by the spectrometer, and the advantages of the present invention also include: First point: the horizontally distributed Raman signal is converted into a vertically distributed Raman signal through the Dove prism. The vertical Raman signal matches the shape of the rectangular receiving slit, so most of the Raman signal can enter the receiving slit, which improves the receiving efficiency of the receiving slit for the Raman signal. Second point: the laser signal converges at the reflection focus many times, so the intensity of the laser signal at the reflection focus is the largest, and the intensity of the Raman signal generated at the reflection focus is the largest; the concave mirror converts the backscattered Raman signal into a Raman signal toward the front lens, which further increases the intensity of the Raman signal; Third point: During the detection process, although the first lens and other optical elements will generate spherical noise, the noise is outside the receiving range of the receiving slit, so the noise will not be received, so the signal-to-noise ratio of the present invention is relatively high; Therefore, in the present invention, most of the Raman signals can enter the receiving slit, and the intensity of the received Raman signals is relatively large. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] Figure 2 It is a structural schematic diagram of Example 2.

[0020] Figure 3 yes Figure 2 Schematic diagram of the structure of the collecting mirror group.

[0021] Figure 4 yes Figure 2 Schematic diagram of the laser signal.

[0022] Figure 5 yes Figure 2 Schematic diagram of the Raman signal.

[0023] Figure 6 yes Figure 5 Magnified view of the reflection focus.

[0024] Figure 7 yes Figure 6 Schematic diagram of the horizontal distribution of Raman signals in the image.

[0025] Figure 8 yes Figure 6 Schematic diagram of the structure of the Zhongdaowei prism.

[0026] Fig. 9 yes Figure 6 Schematic diagram of the vertical distribution of Raman signals.

[0027] Fig.10 yes Figure 2 Schematic diagram of the structure of the receiving slit.

[0028] Fig.11 It is a schematic diagram of the application results of the present invention.

[0029] Fig.12 The schematic diagram of the Dove prism in Example 2 is 45 degrees.

[0030] Fig.13 This is a schematic diagram of the Dove prism in Example 2 with an angle of 135 degrees.

[0031] In the figure: collecting mirror group 1, front lens 11, rear lens 12, Dove prism 13, reflecting mirror group 2, reflection focus 21, first lens 22, second lens 23, first reflecting mirror 24, first transverse surface 241, first vertical surface 242, laser emitter 25, second reflecting mirror 26, second transverse surface 261, second vertical surface 262, receiving slit 3, spectrometer 31, concave mirror 4, laser signal 5, Raman signal 6, horizontally distributed Raman signal 61, vertically distributed Raman signal 62, laser area 7, imaging area 8, conversion area 81. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0033] See also Figure 1 — Fig.13 , a gas Raman signal detection system matching a receiving slit, the system comprising a laser area 7 and an imaging area 8; The imaging area 8 includes a Raman signal 6 , one end of which is received by the receiving slit 3 of the spectrometer 31 along its length direction, and the other end of which is emitted from the reflection focus 21 of the laser area 7 .

[0034] The imaging area 8 includes a collecting lens group 1, which includes a front lens 11, a rear lens 12 and a Dove prism 13 in the same plane. The angle between the Dove prism 13 and the horizontal plane is a certain angle. The rear lens 12 is arranged on the side of the Dove prism 13 close to the receiving slit 3, and the front lens 11 is arranged on the side of the Dove prism 13 away from the receiving slit 3. The focus of the front lens 11 coincides with the reflection focus 21 of the reflecting lens group 2.

[0035] The laser zone 7 includes a reflector group 2; The reflector group 2 includes a first lens 22 and a second lens 23 which are symmetrical along a reflection focus 21. The focus of the first lens 22 coincides with the reflection focus 21. The axis of the first lens 22 is perpendicular to the axis of the front lens 11. The first lens 22 is provided with a first reflector 24 and a laser emitter 25 in a direction away from the reflection focus 21. The axis of the second lens 23 is perpendicular to the axis of the front lens 11. The second lens 23 is provided with a second reflector 26 in a direction away from the reflection focus 21. A concave mirror 4 is provided at the reflection focus 21 in a direction away from the front lens 11.

[0036] The angle between the dove prism 13 and the horizontal plane is 45 degrees or 135 degrees.

[0037] The focal length ratio of the front lens 11 to the rear lens 12 ranges from one half to two times.

[0038] The distance from the concave mirror 4 to the reflection focus 21 is twice the focal length of the concave mirror 4 .

[0039] The width of the first reflector 24 is between one-half inch and two inches, and the width of the second reflector 26 is between one-half inch and two inches.

[0040] The light aperture of the Dove prism 13 is 10 to 50 millimeters, and the length of the receiving slit 3 is 2 to 8 millimeters.

[0041] The first reflector 24 includes a first transverse surface 241 and a first vertical surface 242, one end of the first vertical surface 242 is vertically connected to one end of the first transverse surface 241, and the angle between the first transverse surface 241 and the vertical surface is forty-five degrees; the second reflector 26 includes a second transverse surface 261 and a second vertical surface 262, one end of the second vertical surface 262 is vertically connected to one end of the second transverse surface 261, and the angle between the second transverse surface 261 and the vertical surface is forty-five degrees.

[0042] A method for using a gas Raman signal detection system matching a receiving slit, the method comprising the following steps: The first step: firstly, a large number of laser signals 5 are converged at the reflection focus 21 for multiple times; Step 2: The laser signal 5 at the reflection focus 21 reacts with the gas to be measured at the reflection focus 21 to generate a Raman signal 6; Step 3: The imaging area of ​​the Raman signal 6 in the imaging area 8 becomes parallel to the receiving slit 3 of the spectrometer 31 , and the Raman signal 6 is imaged on the receiving slit 3 of the spectrometer 31 through the lens and the optical path and is received by the receiving slit 3 .

[0043] The supplementary description of the present invention is as follows: The dove prism 13 of the present invention is: Figure 1 — Fig.13 The light in the dove prism 13 usually propagates along the longitudinal axis of the dove prism 13. During the propagation process, the light is reflected once at the bottom surface of the dove prism 13, and an inverted image is formed on the other side of the dove prism 13. When the dove prism 13 is rotated along the longitudinal axis, the image will rotate at twice the rotation angle of the dove prism 13. For example, in the present invention, when the dove prism 13 is rotated forty-five degrees, the Raman signal 6 rotates ninety degrees, and when the dove prism 13 is rotated one hundred and thirty-five degrees, the Raman signal 6 rotates two hundred and seventy degrees, that is, the Raman signal 6 is vertically distributed.

[0044] Embodiment 1: See also Figure 1 — Fig.13 , a gas Raman signal detection system matching a receiving slit, the system includes a laser area 7 and an imaging area 8; the imaging area 8 includes a Raman signal 6, one end of the Raman signal 6 is received by the receiving slit 3 of the spectrometer 31 along its length direction, and the other end of the Raman signal 6 is emitted from the reflection focus 21 of the laser area 7.

[0045] A method for using a gas Raman signal detection system matching a receiving slit, the method comprising the following steps: The first step: firstly, a large number of laser signals 5 are converged at the reflection focus 21 for multiple times; Step 2: The laser signal 5 at the reflection focus 21 reacts with the gas to be measured at the reflection focus 21 to generate a Raman signal 6; Step 3: The imaging area of ​​the Raman signal 6 in the imaging area 8 becomes parallel to the receiving slit 3 of the spectrometer 31 , and the Raman signal 6 is imaged on the receiving slit 3 of the spectrometer 31 through the lens and the optical path and is received by the receiving slit 3 .

[0046] Embodiment 2: The basic content is the same as that of Example 1, except that: See also Figure 1 — Fig.13 The imaging area 8 includes a collecting lens group 1, and the collecting lens group 1 includes a front lens 11, a rear lens 12 and a Dove prism 13 in the same plane. The angle between the Dove prism 13 and the horizontal plane is a certain angle. The Dove prism 13 is provided with a rear lens 12 on the side close to the receiving slit 3, and the Dove prism 13 is provided with a front lens 11 on the side away from the receiving slit 3. The focus of the front lens 11 coincides with the reflection focus 21 of the reflecting lens group 2. The laser zone 7 includes a reflector group 2; the reflector group 2 includes a first lens 22 and a second lens 23 symmetrically along a reflection focus 21, the focus of the first lens 22 coincides with the reflection focus 21, the axis of the first lens 22 is perpendicular to the axis of the front lens 11, and the first lens 22 is provided with a first reflector 24 and a laser emitter 25 in a direction away from the reflection focus 21; the axis of the second lens 23 is perpendicular to the axis of the front lens 11, and the second lens 23 is provided with a second reflector 26 in a direction away from the reflection focus 21; the reflection focus 21 is provided with a concave mirror 4 in a direction away from the front lens 11. The angle between the dove prism 13 and the horizontal plane is forty-five degrees or one hundred and thirty-five degrees. The focal length ratio of the front lens 11 to the rear lens 12 ranges from one-half to two times. The distance from the concave mirror 4 to the reflection focus 21 is twice the focal length value of the concave mirror 4. The width of the first reflector 24 is between one-half inch and two inches, and the width of the second reflector 26 is between one-half inch and two inches. The light aperture of the Dove prism 13 is between ten and fifty millimeters, and the length of the receiving slit 3 is between two and eight millimeters. The first reflector 24 includes a first transverse surface 241 and a first vertical surface 242, one end of the first vertical surface 242 is vertically connected to one end of the first transverse surface 241, and the angle between the first transverse surface 241 and the vertical surface is forty-five degrees; the second reflector 26 includes a second transverse surface 261 and a second vertical surface 262, one end of the second vertical surface 262 is vertically connected to one end of the second transverse surface 261, and the angle between the second transverse surface 261 and the vertical surface is forty-five degrees.

[0047] When in use, the laser signal 5 is converged at the reflection focus 21 through the first lens 22, and then becomes parallel light through the second lens 23, and then reflects multiple times in the second reflector 26 and the first reflector 24; the concave mirror 4 is used to collect the backscattered Raman signal 6; the laser signal 5 located at the reflection focus 21 reacts with the gas to be measured to generate a horizontally distributed Raman signal 61, and the horizontally distributed Raman signal 61 is then reflected once in the Dove prism 13, and then becomes a vertically distributed Raman signal 62, and the vertically distributed Raman signal 62 is then received by the receiving slit 3.

[0048] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A gas Raman signal detection system with a matching receiving slit, characterized in that: The system comprises a laser area (7) and an imaging area (8); The imaging area (8) includes a Raman signal (6), one end of which is received by a receiving slit (3) of a spectrometer (31) along its length direction, and the other end of which is emitted from a reflection focus (21) of a laser area (7).

2. A gas Raman signal detection system with a matching receiving slit according to claim 1, characterized in that: The imaging area (8) comprises a collecting lens group (1), the collecting lens group (1) comprises a front lens (11), a rear lens (12) and a Dove prism (13) in the same plane, the angle between the Dove prism (13) and the horizontal plane is a certain angle, the Dove prism (13) is provided with a rear lens (12) on a side close to the receiving slit (3), the Dove prism (13) is provided with a front lens (11) on a side away from the receiving slit (3), and the focal point of the front lens (11) coincides with the reflection focal point (21) of the reflecting lens group (2).

3. A gas Raman signal detection system with a matching receiving slit according to claim 2, characterized in that: The laser zone (7) comprises a reflector group (2); The reflector group (2) comprises a first lens (22) and a second lens (23) which are symmetrical along a reflection focus (21); the focus of the first lens (22) coincides with the reflection focus (21); the axis of the first lens (22) is perpendicular to the axis of the front lens (11); a first reflector (24) and a laser emitter (25) are arranged on the first lens (22) in a direction away from the reflection focus (21); the axis of the second lens (23) is perpendicular to the axis of the front lens (11); a second reflector (26) is arranged on the second lens (23) in a direction away from the reflection focus (21); and a concave mirror (4) is arranged on the reflection focus (21) in a direction away from the front lens (11).

4. A gas Raman signal detection system with a matching receiving slit according to claim 3, characterized in that: The angle between the Dove prism (13) and the horizontal plane is forty-five degrees or one hundred and thirty-five degrees.

5. A gas Raman signal detection system with a matching receiving slit according to claim 4, characterized in that: The focal length ratio of the front lens (11) to the rear lens (12) ranges from one-half to two times.

6. A gas Raman signal detection system with a matching receiving slit according to claim 5, characterized in that: The distance from the concave mirror (4) to the reflection focus (21) is twice the focal length of the concave mirror (4).

7. A gas Raman signal detection system with a matching receiving slit according to claim 6, characterized in that: The width of the first reflector (24) is between one-half inch and two inches, and the width of the second reflector (26) is between one-half inch and two inches.

8. The gas Raman signal detection system with matching receiving slit according to claim 7, characterized in that: The light aperture of the Dove prism (13) is ten to fifty millimeters, and the length of the receiving slit (3) is two to eight millimeters.

9. A gas Raman signal detection system with matching receiving slit according to claim 8, characterized in that: The first reflector (24) comprises a first transverse surface (241) and a first vertical surface (242), one end of the first vertical surface (242) being vertically connected to one end of the first transverse surface (241), and the angle between the first transverse surface (241) and the vertical surface is forty-five degrees; the second reflector (26) comprises a second transverse surface (261) and a second vertical surface (262), one end of the second vertical surface (262) being vertically connected to one end of the second transverse surface (261), and the angle between the second transverse surface (261) and the vertical surface is forty-five degrees.

10. The method for using the gas Raman signal detection system with a matching receiving slit according to claim 1, characterized in that: The method of use comprises the following steps: The first step is to converge a large number of laser signals (5) at the reflection focus (21) multiple times; Step 2: The laser signal (5) at the reflection focus (21) reacts with the gas to be measured at the reflection focus (21) to generate a Raman signal (6); Step 3: The imaging area of ​​the Raman signal (6) in the imaging area (8) is changed to a direction parallel to the receiving slit (3) of the spectrometer (31), and the Raman signal (6) is imaged on the receiving slit (3) of the spectrometer (31) through the lens and the optical path, and is received by the receiving slit (3).

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