Two-point calibration multi-pass cell supporting single-point gas tagging

Abstract

This invention relates to the field of optical detection technology and discloses a dual-point calibration multi-pass cell supporting single-point calibration gas. It includes a cylindrical body and two end caps, with the cylindrical body positioned between the two end caps. A third cavity mirror is disposed inside the cylindrical body and fixedly mounted to one end of one of the end caps. When the second cavity mirror moves closer to the first cavity mirror, it causes a fourth cavity mirror to extend from a second through-hole. When the second cavity mirror touches the outer surface of the first cavity mirror, the fourth cavity mirror inserts into the first hole. At this point, the end face of the fourth cavity mirror is flush with the outer surface of the first cavity mirror on the side closest to the third cavity mirror. This design allows the second cavity mirror to move as needed, avoiding disassembly and reassembly of the first cavity mirror, reducing scratches on the mirror surface caused by disassembly and reassembly, ensuring accurate gas detection and resulting in more accurate detection results.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and more particularly to a two-point calibration multipass cell that supports single-point calibration gas. Background Technology

[0002] Multipass cell technology is a method used in optical detection to increase the interaction distance between a laser beam and a gas sample, thereby improving detection sensitivity. It mainly consists of a specific number of mirrors. When a laser beam enters the multipass cell through the outer optical path, it is constrained between the mirrors and reflected multiple times before exiting the cell from the entrance, achieving an optical path of several meters to tens of meters. Multipass cell technology, combined with Tunable Semiconductor Laser Absorption Spectroscopy (TDLAS), has been widely applied in various fields due to its high sensitivity, high selectivity, and fast response. These applications include environmental monitoring for air quality detection and greenhouse gas detection; combustion diagnostics for combustion efficiency assessment and pollutant emission monitoring; medical diagnostics for respiratory gas analysis and blood gas analysis; industrial control for monitoring reaction processes and leak detection; and agriculture for greenhouse gas management and soil gas analysis. With continuous technological advancements, its application potential in even more fields will be further explored.

[0003] An existing multi-channel cavity structure for rapid dual-point calibration with a single-concentration standard gas (publication number: CN119779987A) alters the original optical path by adding a double-sided cavity mirror between two spherical cavity mirrors, resulting in two possible scenarios: one with half the optical path and the other with twice the optical path. Since spherical cavity mirrors one, two, and the double-sided cavity mirror are all installed inside a transparent glass tube, the user must open the transparent glass tube and install the double-sided cavity mirror when it is needed. Because the surfaces of spherical cavity mirrors one and two need to reflect light, frequent disassembly and reassembly can easily scratch the mirror surfaces, leading to severe light scattering in subsequent use and affecting the accuracy of the test results. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a dual-point calibration multi-pass cell that supports single-point calibration gas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: Supports dual-point calibration multi-pass cells with single-point standard gas, including: A cylindrical body and two end caps, wherein the cylindrical body is disposed between the two end caps; The third endoscope is located inside the cylinder and is fixedly installed on one end of one of the end caps; The second cavity mirror is located inside the cylinder and close to another end cap. The second cavity mirror is configured to move along the central axis of the cylinder, and a second through hole is provided on the outer surface of the second cavity mirror. The first cavity mirror is fixedly installed inside the cylinder and positioned between the third cavity mirror and the second cavity mirror. A first hole is provided through the outer surface of the first cavity mirror. The fourth cavity mirror is disposed inside the second through hole. The fourth cavity mirror is coupled to the second cavity mirror. The fourth cavity mirror is configured to move along the central axis of the cylinder when the second cavity mirror moves along the central axis of the cylinder. The outer surface of the third cavity mirror has a second hole through it, and the outer surface of the third cavity mirror has a third hole through it. A laser and a detector are fixedly installed on the outer surface of the end cap near the second hole, and an air inlet pipe is fixedly installed on the outer surface of the end cap near the third hole.

[0006] As a further embodiment of the present invention, the fourth cavity mirror and the first hole are arranged on the same axis, and the fourth cavity mirror and the first hole are matched.

[0007] As a further embodiment of the present invention, a circular plate is slidably installed on the inner wall of the cylinder, and the second cavity mirror is fixedly installed on the outer surface of the circular plate near the first cavity mirror. A circular sleeve is fixedly connected to the outer surface of the circular plate opposite to the second cavity mirror. A hollow rod is sleeved on the outer surface of the circular sleeve. The hollow rod and the second cavity mirror are arranged on the same axis. The other end of the hollow rod passes through the outer surface of one of the end caps and is slidably installed therewith.

[0008] As a further embodiment of the present invention, the outer surface of the circular plate is provided with the same second through hole, the fourth cavity mirror is fixedly installed with a first support rod at one end near the hollow rod, a guide post is fixedly connected to one end of the first support rod, a ring is fixedly connected to the outer circumference of the hollow rod, a guide groove is provided on the outer circumference of the ring, the guide groove is spirally arranged, the guide post is slidably installed with the inner wall of the guide groove, and the hollow rod is rotatably installed with the circular sleeve.

[0009] As a further embodiment of the present invention, a first C-shaped limiting post is fixedly connected to the outer surface of the circular plate near the circular ring, and a first limiting post is fixedly connected to the lower surface of the first support rod. A first C-shaped opening is opened on the outer surface of the first C-shaped limiting post, and the first limiting post is slidably inserted between the inner walls of the first C-shaped opening.

[0010] As a further embodiment of the present invention, a first through hole is provided on the outer surface of the circular plate and the center of the second cavity mirror. A push rod is slidably inserted into the inner wall of the first through hole. The push rod is located inside the circular sleeve. Two second support rods are symmetrically fixedly connected to one end of the push rod near the circular ring.

[0011] As a further embodiment of the present invention, two vertical grooves are symmetrically formed on the outer circumference of the hollow rod, and two horizontal grooves are symmetrically formed on the outer circumference of the hollow rod. The adjacent horizontal grooves and vertical grooves are connected. The horizontal grooves and vertical grooves are arranged in an L-shape. One end of the second support rod passes through the outer surface of the hollow rod and is disposed between the inner walls of the horizontal grooves and vertical grooves. A circular hole is formed through the interior of the hollow rod, and the horizontal grooves and vertical grooves are connected to the circular hole.

[0012] As a further embodiment of the present invention, two second C-shaped limiting posts are fixedly connected to the outer surface of the circular plate near the annulus. The lower surfaces of the two second support rods at opposite ends are each fixedly equipped with a second limiting post. The outer surface of the second limiting post is provided with a second C-shaped opening, and the second limiting post is slidably inserted between the inner walls of the second C-shaped opening.

[0013] As a further embodiment of the present invention, a tension spring is sleeved on the outer surface of the second limiting post, one end of the tension spring is fixedly connected to the lower surface of the second support rod, and the other end of the tension spring is fixedly connected to the top end of the second C-shaped limiting post.

[0014] As a further embodiment of the present invention, the inner wall of the cylinder is provided with a strip-shaped protrusion along its axial direction, and the circumferential surface of the circular plate is provided with a groove that matches the strip-shaped protrusion, and the strip-shaped protrusion and the groove are slidably installed.

[0015] As a further embodiment of the present invention, a second hole is provided through the outer surface of the third cavity mirror so that the laser can enter the inside of the cylinder, and a third hole is provided through the outer surface of the third cavity mirror so that the gas can enter the inside of the cylinder.

[0016] When the second cavity mirror moves closer to the first cavity mirror, it causes the fourth cavity mirror to extend out from the second through hole. When the second cavity mirror touches the outer surface of the first cavity mirror, the fourth cavity mirror is inserted into the first hole. At this time, the end face of the fourth cavity mirror is flush with the outer surface of the first cavity mirror on the side closer to the third cavity mirror. This setting allows the second cavity mirror to move as needed, thereby avoiding the need to disassemble the first cavity mirror, reducing scratches on the mirror surface caused by disassembly and ensuring that the gas can be correctly detected subsequently, making the detection results more accurate. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the dual-point calibration multi-pass cell that supports single-point calibration gas proposed in this invention. Figure 2 This is a schematic diagram of the left-side structure of the dual-point calibration multi-pass cell that supports single-point calibration gas proposed in this invention. Figure 3 This is a cross-sectional view of the multi-pass cell for dual-point calibration that supports single-point calibration gas, as proposed in this invention. Figure 4 This is a schematic diagram of the end cap of the dual-point calibration multi-pass cell that supports single-point calibration gas as proposed in this invention. Figure 5 This is a cross-sectional view of the end cap of the multi-pass cell for dual-point calibration that supports single-point calibration gas proposed in this invention. Figure 6 This is a schematic diagram of a circular plate for a dual-point calibration multi-pass cell that supports single-point calibration gas, as proposed in this invention. Figure 7 This is a schematic diagram of the fourth endoscope for a dual-point calibration multi-pass cell that supports single-point calibration gas, as proposed in this invention. Figure 8 This is a cross-sectional schematic diagram of the circular plate of the multi-pass cell for dual-point calibration that supports single-point calibration gas as proposed in this invention. Figure 9 This is a top view of the circular plate of the multi-pass cell for dual-point calibration that supports single-point calibration gas, as proposed in this invention. Figure 10 A schematic diagram of the hollow rod of the dual-point calibration multi-pass cell supporting single-point calibration gas proposed in this invention; Figure 11 for Figure 6 Enlarged view of a portion of point A in the middle; Figure 12 This is a schematic diagram of the light spot distribution of the dual-point calibration multi-pass cell that supports single-point standard gas as proposed in this invention. Figure 13 This is a schematic diagram showing the reflection of light from the third cavity mirror and the first cavity mirror in the dual-point calibration multi-pass cell that supports single-point standard gas proposed in this invention. Figure 14 This is a schematic diagram showing the reflection of light from the third cavity mirror, the first cavity mirror, and the second cavity mirror in the dual-point calibration multi-pass cell that supports single-point calibration gas proposed in this invention.

[0018] In the picture: 100. Cylinder body; 200. End cap; 300. First cavity mirror; 310. First hole; 400. Second cavity mirror; 500. Third cavity mirror; 510. Second hole; 520. Third hole; 600, Circular plate; 610, First C-type limiting post; 620, Second C-type limiting post; 630, Circular sleeve; 700, Hollow rod; 710, Vertical groove; 720, Horizontal groove; 800, Circular ring; 810, Guide groove; 900, Fourth cavity mirror; 1000, Push rod; 1100, First support rod; 1110, First limiting post; 1120, Guide post; 1200, Second support rod; 1210, Second limiting post; 1300, Tension spring; 1400, First through hole; 1500, Second through hole. Detailed Implementation

[0019] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0020] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" 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; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In order to adjust the position of the internal cavity mirror and change the optical path without disassembling the multi-pass cell, such as... Figure 1 and Figure 2 As shown, this invention proposes a dual-point calibration multi-pass cell supporting single-point calibration gas, comprising: a cylinder 100, two end caps 200, a third cavity mirror 500, a first cavity mirror 300, and a fourth cavity mirror 900. Specifically, the cylinder 100 is disposed between the two end caps 200. The cylinder 100 is made of transparent glass. The two end caps 200 clamp the cylinder 100 in the middle by connecting rods, firmly fixing the position of the cylinder 100, and sealing both ends of the cylinder 100 by the two end caps 200 to prevent gas leakage during subsequent use.

[0023] To achieve gas detection, such as Figure 1 and Figure 2As shown, the third cavity mirror 500 is disposed inside the cylinder 100 and fixedly installed at one end of one of the end caps 200. The second cavity mirror 400 is disposed inside the cylinder 100 and close to the other end cap 200. The laser beam is reflected inside the cylinder 100 through the cooperation of the third cavity mirror 500 and the second cavity mirror 400, thereby coming into contact with the gas. Finally, the reflected laser beam is received by a receiver. In order to change the optical path distance, the first cavity mirror 300 is fixedly disposed inside the cylinder 100 and positioned between the third cavity mirror 500 and the second cavity mirror 400. When the laser beam is reflected inside the cylinder 100, the optical path distance can be changed by two times or half as needed.

[0024] In this embodiment, in order to avoid disassembling the first laparoscope 300, such as Figure 9 As shown, a second through hole 1500 is provided through the outer surface of the second cavity mirror 400, such as... Figure 1 and Figure 2 As shown, the outer surface of the first cavity mirror 300 has a first hole 310 through it, and the fourth cavity mirror 900 is disposed inside the second through hole 1500. In actual application, the mirror surface of the fourth cavity mirror 900 is flush with the mirror surface of the second cavity mirror 400 to ensure that the trajectory of light reflection will not have a large error. When the second cavity mirror 400, the fourth cavity mirror 900 and the third cavity mirror 500 are located at both ends and the first cavity mirror 300 is located in the middle, such as Figure 14 As shown, after being refracted by the third cavity mirror 500 and the first cavity mirror 300, the laser light enters through the first hole 310 and is refracted between the second cavity mirror 400, the fourth cavity mirror 900, and the first cavity mirror 300, thus doubling the optical path. To achieve the above objective, the second cavity mirror 400 is configured to move along the central axis of the cylinder 100 (the specific movement method is detailed below). The fourth cavity mirror 900 is coupled to the second cavity mirror 400, and is configured to move along the central axis of the cylinder 100 when the second cavity mirror 400 moves along the central axis of the cylinder 100. In actual use, when the second cavity mirror 400 moves closer to the first cavity mirror 300, it will cause the fourth cavity mirror 900 to extend out from the second through hole 1500. When the second cavity mirror 400 is attached to the outer surface of the first cavity mirror 300, the fourth cavity mirror 900 will be inserted into the first hole 310. At this time, the end face of the fourth cavity mirror 900 is flush with the outer surface of the first cavity mirror 300 on the side closer to the third cavity mirror 500. This setting allows the second cavity mirror 400 to move as needed, thereby avoiding disassembly and assembly of the first cavity mirror 300, reducing scratches on the mirror surface caused by disassembly and assembly, ensuring that the gas can be correctly detected subsequently, and making the detection results more accurate; Figure 13 As shown, when the surfaces of the fourth cavity mirror 900 and the first cavity mirror 300 are flush, light is reflected between the two.

[0025] It is important to note that, in order for the fourth cavity mirror 900 to be smoothly inserted into the first hole 310, the fourth cavity mirror 900 and the first hole 310 are arranged on the same axis and are matched. When the second cavity mirror 400 and the first cavity mirror 300 are in repeated contact during use, it is easy for friction to occur between their surfaces, resulting in scratches and particle peeling, which will affect subsequent testing. To avoid this problem, in the actual design, an annular protective film is attached to the surface of the refractive mirror of the second cavity mirror 400. The thickness of the annular protective film is 0.05 mm and the width is 0.15 mm, so that there is a 0.05 mm gap between the second cavity mirror 400 and the first cavity mirror 300, which will not cause friction and collision due to contact. In addition, the annular protective film has a hole in the middle, so it will not cover the effective refractive mirror surface of the second cavity mirror 400.

[0026] In this embodiment, in order to enable the second cavity mirror 400 to move along the central axis of the cylinder 100, such as... Figure 3 , Figure 4 and Figure 5 As shown, a circular plate 600 is slidably mounted on the inner wall of the cylinder 100. The second cavity mirror 400 is fixedly mounted on the outer surface of the circular plate 600 near the first cavity mirror 300. In actual application, the second cavity mirror 400 and the circular plate 600 are fixedly bonded together with glue. A circular sleeve 630 is fixedly connected to the outer surface of the circular plate 600 opposite to the second cavity mirror 400. A hollow rod 700 is fitted on the outer surface of the circular sleeve 630. The hollow rod 700 and the second cavity mirror 400 are located on the same axis. The other end of the hollow rod 700 passes through the outer surface of one of the end caps 200 and is slidably mounted thereto. In actual operation, the operator manually pushes the hollow rod 700 to push the circular plate 600 closer to the first cavity mirror 300, and the circular plate 600 drives the second cavity mirror 400 closer to the first cavity mirror 300.

[0027] In this embodiment, in order to cause the fourth cavity mirror 900 to extend from the inside of the second through hole 1500 when the second cavity mirror 400 moves closer to the first cavity mirror 300, as shown in the example... Figure 6 and Figure 7As shown, the outer surface of the circular plate 600 is provided with the same second through hole 1500. The fourth cavity mirror 900 is fixedly installed with a first support rod 1100 at one end near the hollow rod 700. A guide post 1120 is fixedly connected to one end of the first support rod 1100. A ring 800 is fixedly connected to the outer circumference of the hollow rod 700. A guide groove 810 is provided on the outer circumference of the ring 800. The guide groove 810 is spirally arranged. The guide post 1120 is slidably installed with the inner wall of the guide groove 810. The hollow rod 700 is rotatably installed with the circular sleeve 630. In actual use, when the operator manually rotates the hollow rod 700, it will drive the ring 800 to rotate. The ring 800, through the cooperation of the guide post 1120 and the guide groove 810, drives the fourth cavity mirror 900 to move closer to the first cavity mirror 300, so that the fourth cavity mirror 900 extends out of the second through hole 1500 and is then inserted into the first hole 310.

[0028] In order to prevent the circular plate 600 from rotating when the hollow rod 700 rotates, thereby ensuring that the circular plate 600 can only move along the central axis of the cylinder 100, a strip-shaped protrusion is provided on the inner wall of the cylinder 100. A groove matching the strip-shaped protrusion is formed on the circumferential surface of the circular plate 600. The strip-shaped protrusion and the groove are slidably installed, and the circular plate 600 is restricted from rotating by the cooperation of the strip-shaped protrusion and the groove.

[0029] To restrict the fourth cavity mirror 900 to move only along the central axis of the cylinder 100 and prevent it from rotating, such as Figure 8 As shown, a first C-shaped limiting post 610 is fixedly connected to the outer surface of the circular plate 600 near the ring 800, and a first limiting post 1110 is fixedly connected to the lower surface of the first support rod 1100. A first C-shaped opening is provided on the outer surface of the first C-shaped limiting post 610. The first limiting post 1110 is slidably inserted between the inner walls of the first C-shaped opening. By setting the first C-shaped opening, air can flow when the first limiting post 1110 slides on its inner wall, and the first limiting post 1110 will not be unable to slide due to changes in air pressure.

[0030] Because the fourth cavity mirror 900 needs to keep its end face flush with the surface of the second cavity mirror 400 when it is not protruding from the second through hole 1500, and when the fourth cavity mirror 900 protrudes from the second through hole 1500 and is inserted into the first hole 310, the end face of the fourth cavity mirror 900 needs to be flush with the mirror surface of the first cavity mirror 300. Therefore, when the second cavity mirror 400 moves close to the first cavity mirror 300, it needs to be completely in contact with the surface of the first cavity mirror 300. To check whether it is completely in contact, such as... Figure 9 As shown, a first through hole 1400 is provided through the outer surface of both the circular plate 600 and the second cavity mirror 400 at their center positions. Figure 4 and Figure 8As shown, a push rod 1000 is slidably inserted into the inner wall of the first through hole 1400. The push rod 1000 is disposed inside the circular sleeve 630, as... Figure 10 and Figure 11 As shown, two second support rods 1200 are symmetrically fixed to one end of the push rod 1000 near the ring 800. Two vertical grooves 710 and two horizontal grooves 720 are symmetrically formed on the outer circumference of the hollow rod 700. Adjacent horizontal grooves 720 and vertical grooves 710 are connected, and the horizontal grooves 720 and vertical grooves 710 are arranged in an L-shape. One end of the second support rod 1200 penetrates the outer surface of the hollow rod 700 and is positioned between the inner walls of the horizontal grooves 720 and vertical grooves 710. When the second cavity mirror 400 moves closer to the first cavity mirror 300, it will cause the end face of the push rod 1000 to abut against the first cavity mirror 300. At this time, if the second cavity mirror 400 continues to move closer to the first cavity mirror 300, it will press the push rod 1000 back into the first through hole 140. Inside the cavity 310, the top rod 1000 moves away from the first cavity mirror 300 relative to the hollow rod 700, thereby causing the second support rod 1200 to slide out of the vertical groove 710. When the second cavity mirror 400 and the first cavity mirror 300 come into contact, the second support rod 1200 slides completely out of the vertical groove 710. At this time, the vertical groove 710 releases the restriction on the second support rod 1200. When the user rotates the hollow rod 700, the hollow rod 700 can be rotated, and the second support rod 1200 will slide into the horizontal groove 720 until the second support rod 1200 comes into contact with the inner wall of the other end of the horizontal groove 720. At this time, the hollow rod 700 stops rotating. Through this setting, the fourth cavity mirror 900 can remain flush with the mirror surface of the first cavity mirror 300 when it is inserted into the first hole 310, ensuring that the path of subsequent light refraction is accurate.

[0031] To limit the installation position of the top rod 1000 and prevent it from rotating, such as Figure 8 and Figure 11 As shown, two second C-shaped limiting posts 620 are fixedly connected to the outer surface of the circular plate 600 near the circular ring 800, and two second limiting posts 1210 are fixedly installed on the lower surfaces of the two second support rods 1200 at their opposite ends. Figure 9As shown, the outer surface of the second limiting post 1210 is provided with a second C-shaped opening. The second limiting post 1210 is slidably inserted between the inner walls of the second C-shaped opening. The installation position of the top rod 1000 is limited by the cooperation of the second limiting post 1210 and the second C-shaped opening. At the same time, the setting of the second C-shaped opening allows air to flow when the second limiting post 1210 moves within the inner wall of the second C-shaped opening, and the second limiting post 1210 will not be unable to slide due to changes in air pressure. Meanwhile, in order for the cavity inside the cylinder 100 to adapt to pressure changes when the second cavity mirror 400 moves, a circular hole is provided through the interior of the hollow rod 700, and the horizontal groove 720 and the vertical groove 710 are connected to the circular hole.

[0032] In order for the circular plate 600 to move back to its original position after moving away from the first cavity mirror 300, the operator can rotate the hollow rod 700 in the opposite direction to allow the push rod 1000 to reset. Figure 8 As shown, a tension spring 1300 is sleeved on the outer surface of the second limiting post 1210. One end of the tension spring 1300 is fixedly connected to the lower surface of the second support rod 1200, and the other end of the tension spring 1300 is fixedly connected to the top end of the second C-shaped limiting post 620. The elastic force of the tension spring 1300 enables the top rod 1000 to be reset and extend out of the first through hole 1400.

[0033] It should be noted that the contact surface between the circular plate 600 and the inner wall of the cylinder 100 needs to be sealed with a sealing strip to prevent gas leakage. The friction between the sealing strip and the cylinder 100 ensures that the circular plate 600 can maintain its current position when it is not pushed.

[0034] In this embodiment, a second hole 510 is formed through the outer surface of the third cavity mirror 500, and a third hole 520 is formed through the outer surface of the third cavity mirror 500. A laser and a detector are fixedly installed on the outer surface of the end cap 200 near the second hole 510, and an air inlet pipe is fixedly installed on the outer surface of the end cap 200 near the third hole 520. In actual use, the gas to be measured is injected through the air inlet pipe, and the gas enters the cylinder 100 through the third hole 520. The laser emits a laser beam that enters the cylinder 100 through the second hole 510. The light beam is reflected by the first cavity mirror 300, the second cavity mirror 400, the third cavity mirror 500, and the fourth cavity mirror 900, and then emitted from the second hole 510. It is received and analyzed by the detector.

[0035] In this embodiment, the inner wall of the cylinder 100 is provided with a strip-shaped protrusion along the axial direction, and the circumferential surface of the circular plate 600 is provided with a groove that matches the protrusion. This arrangement restricts the circular plate 600 to move only along the axial direction of the cylinder 100.

[0036] In this embodiment, as Figure 12 The diagram shows the light spot distribution of the first cavity mirror 300.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A multi-pass cell supporting dual-point calibration with single-point standard gas, characterized in that, include: A cylindrical body (100) and two end caps (200), wherein the cylindrical body (100) is disposed between the two end caps (200); The third endoscope (500) is located inside the cylinder (100) and is fixedly installed on one end of one of the end caps (200); The second cavity mirror (400) is disposed inside the cylinder (100) and close to another end cap (200). The second cavity mirror (400) is configured to be movable along the central axis of the cylinder (100). A second through hole (1500) is provided on the outer surface of the second cavity mirror (400). The first cavity mirror (300) is fixedly disposed inside the cylinder (100) and between the third cavity mirror (500) and the second cavity mirror (400). A first hole (310) is provided through the outer surface of the first cavity mirror (300). A fourth cavity mirror (900) is disposed inside the second through hole (1500). The fourth cavity mirror (900) is coupled to the second cavity mirror (400). The fourth cavity mirror (900) is configured to move along the central axis of the cylinder (100) when the second cavity mirror (400) moves along the central axis of the cylinder (100). The outer surface of the third cavity mirror (500) is provided with a second hole (510) and a third hole (520). A laser and a detector are fixedly installed on the outer surface of the end cap (200) near the second hole (510), and an air inlet pipe is fixedly installed on the outer surface of the end cap (200) near the third hole (520).

2. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 1, characterized in that, The fourth cavity mirror (900) and the first hole (310) are located on the same axis and are matched with each other.

3. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 1, characterized in that, A circular plate (600) is slidably installed on the inner wall of the cylinder (100). The second cavity mirror (400) is fixedly installed on the outer surface of the circular plate (600) near the first cavity mirror (300). A circular sleeve (630) is fixedly connected to the outer surface of the circular plate (600) opposite to the second cavity mirror (400). A hollow rod (700) is sleeved on the outer surface of the circular sleeve (630). The hollow rod (700) and the second cavity mirror (400) are located on the same axis. The other end of the hollow rod (700) passes through the outer surface of one of the end caps (200) and is slidably installed therewith.

4. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 3, characterized in that, The outer surface of the circular plate (600) is provided with the same second through hole (1500). The fourth cavity mirror (900) is fixedly installed with a first support rod (1100) at one end near the hollow rod (700). A guide post (1120) is fixedly connected to one end of the first support rod (1100). A ring (800) is fixedly connected to the outer circumference of the hollow rod (700). A guide groove (810) is provided on the outer circumference of the ring (800). The guide groove (810) is spirally arranged. The guide post (1120) is slidably installed with the inner wall of the guide groove (810). The hollow rod (700) is rotatably installed with the circular sleeve (630).

5. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 4, characterized in that, The outer surface of the circular plate (600) near the ring (800) is fixedly connected to a first C-shaped limiting post (610), and the lower surface of the first support rod (1100) is fixedly connected to a first limiting post (1110). The outer surface of the first C-shaped limiting post (610) is provided with a first C-shaped opening, and the first limiting post (1110) is slidably inserted between the inner walls of the first C-shaped opening.

6. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 4, characterized in that, The outer surface of the circular plate (600) and the second cavity mirror (400) at the center position is provided with a first through hole (1400). A push rod (1000) is slidably inserted into the inner wall of the first through hole (1400). The push rod (1000) is located inside the circular sleeve (630). Two second support rods (1200) are symmetrically fixedly connected to one end of the push rod (1000) near the circular ring (800).

7. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 6, characterized in that, The hollow rod (700) has two vertical grooves (710) symmetrically opened on its outer circumference surface, and two horizontal grooves (720) symmetrically opened on its outer circumference surface. The adjacent horizontal grooves (720) and vertical grooves (710) are connected. The horizontal grooves (720) and vertical grooves (710) are arranged in an L-shape. One end of the second support rod (1200) passes through the outer surface of the hollow rod (700) and is located between the inner walls of the horizontal grooves (720) and vertical grooves (710). A circular hole is opened through the interior of the hollow rod (700), and the horizontal grooves (720) and vertical grooves (710) are connected to the circular hole.

8. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 7, characterized in that, Two second C-shaped limiting posts (620) are fixedly connected to the outer surface of the circular plate (600) near the circular ring (800). Two second limiting posts (1210) are fixedly installed on the lower surfaces of the two second support rods (1200) at opposite ends. The outer surface of the second limiting post (1210) is provided with a second C-shaped opening. The second limiting post (1210) is slidably inserted between the inner walls of the second C-shaped opening.

9. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 8, characterized in that, A tension spring (1300) is fitted on the outer surface of the second limiting post (1210). One end of the tension spring (1300) is fixedly connected to the lower surface of the second support rod (1200), and the other end of the tension spring (1300) is fixedly connected to the top end of the second C-shaped limiting post (620).

10. The dual-point calibration multi-pass cell supporting single-point calibration gas as described in claim 3, characterized in that, The inner wall of the cylinder (100) is provided with a strip-shaped protrusion along its axial direction, and the circumferential surface of the circular plate (600) is provided with a groove that matches the strip-shaped protrusion. The strip-shaped protrusion and the groove are slidably installed.

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