An absorption spectrum calibration device and a calibration method thereof

Abstract

This invention relates to an absorption spectroscopy calibration device and method, belonging to the field of spectral parameter measurement. The device includes a furnace tube and light guide assemblies symmetrically arranged at both ends of the furnace tube. Each light guide assembly includes a light guide tube and windows sealingly connected to both ends of the light guide tube. One end of the light guide tube extends into the cavity of the furnace tube and is suspended in the middle region of the cavity, while the other end of the light guide tube is located outside the furnace tube. The light guide assembly provides a vacuum transmission optical path for spectral instrument calibration. This invention, by using the furnace tube and its inner cavity as a sealed cavity, the symmetrically arranged light guide assemblies at both ends of the furnace tube, and the arrangement of the light guide tube and the windows sealingly connected to both ends of the light guide tube, not only provides a sealed calibration environment but also, by using the sealed space of the light guide tube as a vacuum transmission optical path, replaces the optical path of laser light in these optical media with the optical path in a vacuum, reducing light intensity loss and improving the measurement signal-to-noise ratio.

Description

Technical Field

[0001] This invention belongs to the field of spectral parameter measurement, and specifically relates to an absorption spectrum calibration device and its calibration method. Background Technology

[0002] Based on the principle of infrared laser absorption, the technology for measuring gas composition and concentration is becoming increasingly mature and has a wide range of applications. Its measurement accuracy depends on the accuracy of spectral parameters. Currently, publicly available spectral parameter databases, such as HITRAN or HITEMP, have uncertainties of 10%-20% for some spectral parameters. The magnitude of these uncertainties directly affects the measurement accuracy of absorption spectrometers. Therefore, to improve the accuracy of spectral measurements, it is necessary to accurately measure spectral parameters and perform high-precision corrections on the spectral parameters in publicly available databases. One commonly used method for measuring spectral information of standard gases is to construct a standard high-temperature environment. For example, existing calibration devices typically use a light-transmitting rod (made of sapphire or ruby) as a light guide in the high-temperature environment. However, the transmittance of this light-transmitting rod decreases rapidly with increasing temperature, and its transmittance also decreases rapidly with increasing length, making the calibration device unsuitable for mid-infrared absorption spectrometers.

[0003] Therefore, in response to the above problems, we continue to provide calibration devices for absorption spectrometers that are applicable to the mid-infrared band. Summary of the Invention

[0004] To address the above problems, the present invention provides an absorption spectrum calibration device and a calibration method thereof.

[0005] The first objective of this invention is to provide an absorption spectrum calibration device, comprising a furnace tube and light guide components symmetrically arranged at both ends of the furnace tube;

[0006] The light guide assembly includes a light guide tube and a window that is sealed at both ends of the light guide tube. One end of the light guide tube extends into the cavity of the furnace tube and is suspended in the middle area of ​​the cavity. The other end of the light guide tube is located outside the furnace tube.

[0007] The light guide assembly is used to provide a vacuum transmission optical path for the calibration of the spectrometer.

[0008] In a specific embodiment of the present invention, a purging component is provided at the end of the light guide component located outside the furnace tube;

[0009] The purging assembly includes a first-stage sealed box and a second-stage sealed box, with the first-stage sealed box located inside the second-stage sealed box;

[0010] The first-stage sealed box is used to house the transmitting or receiving unit of the absorption spectrometer;

[0011] The first-stage sealed box is equipped with an air inlet pipe and an air outlet. The air inlet pipe penetrates the wall of the second-stage sealed box and extends to the outside of the second-stage sealed box. The second-stage sealed box is equipped with an air outlet.

[0012] In a specific embodiment of the present invention, the window near the transmitting unit is the first window, and the first window is located between the second-level sealed box and the light guide tube;

[0013] The second-stage sealed box is sealed with a first water-cooled flange, and the second-stage sealed box is pressed and connected to the first window through the first water-cooled flange;

[0014] The end of the light guide tube is sealed with a second water-cooled flange, and the light guide tube is pressed and connected to the first window through the second water-cooled flange.

[0015] In a specific embodiment of the present invention, a channel is provided on the second water-cooled flange, and the channel is connected to a first vacuum pump, which is connected to the light guide tube through the channel.

[0016] In a specific embodiment of the present invention, a third water-cooled flange is provided at the connection between the light guide tube and the furnace tube.

[0017] In a specific embodiment of the present invention, the third water-cooled flange near the launching unit is connected to an atmosphere generating component, and the atmosphere generating component is connected to the furnace tube.

[0018] The third water-cooled flange near the receiving unit is connected to a second vacuum pump, which is connected to the furnace tube;

[0019] A pressure gauge is also installed on the third water-cooled flange near the receiving unit.

[0020] In a specific embodiment of the present invention, the window located inside the furnace tube is a second window, and the second window and the light guide tube are sealed together by an ultra-smooth surface bonding process.

[0021] In a specific embodiment of the present invention, both the light guide tube and the window are made of sapphire.

[0022] The furnace tube contains a resistance wire and several thermocouples.

[0023] In a specific embodiment of the present invention, the device further includes an absorption spectrometer, which includes a transmitting unit and a receiving unit, and an adjustment frame is provided at the bottom of both the transmitting unit and the receiving unit.

[0024] A second objective of this invention is to provide a method for calibrating the absorption spectrum of the aforementioned absorption spectrum calibration device, comprising:

[0025] The furnace tube is heated until the temperature of the sealed cavity of the furnace tube reaches the preset temperature;

[0026] Vacuuming and purging of the furnace tubes; after completing vacuuming and purging, vacuuming of the light guide components;

[0027] A standard atmosphere is introduced into the sealed cavity of the furnace tube until the predetermined pressure is reached. After a certain period of time, the temperature and pressure changes inside the furnace tube are observed. When the temperature and pressure changes inside the furnace tube reach the calibration conditions, the absorption spectrum calibration at the preset temperature is completed.

[0028] The beneficial effects of this invention are:

[0029] This invention discloses an absorption spectrum calibration device and method. Using a furnace tube and its inner cavity as a sealed chamber, symmetrically arranged light guide components at both ends of the furnace tube, and the light guide tubes within these components with sealed windows at both ends, this not only provides a sealed calibration environment (sealed chamber), but also utilizes the sealed light guide tube space as a vacuum transmission optical path. This replaces the optical path of the laser in these optical media with the optical path in a vacuum, reducing light intensity loss, improving the measurement signal-to-noise ratio, and avoiding the situation where "when mid-infrared laser light passes through a certain length of optical material such as a sapphire rod, the light intensity attenuates due to the absorption characteristics of the optical material itself along its transmission path." This enables the calibration of mid-infrared absorption spectrometers under high-temperature conditions, solving the problem that ordinary devices cannot be used for mid-infrared absorption spectrometer calibration.

[0030] Moreover, the present invention also has the following advantages:

[0031] One end of the light guide tube is sealed in the calibration environment through a bonding process. The other end of the light guide tube is compressed and sealed through multiple water-cooled flanges and sealing rings, forming a sealed space inside the light guide tube, which lays the foundation for the subsequent vacuum transmission optical path. Secondly, air holes are started on the water-cooled flange (i.e., the second water-cooled flange) near the port of the light guide tube at the compression and sealing connection to connect the first vacuum pump, so that the first vacuum pump is connected to the light guide tube, realizing the design of the light guide tube as a vacuum transmission optical path. Moreover, while evacuating the vacuum, the absorption interference problem of stray gas in the light guide device is solved, and the measurement accuracy of spectral parameters is improved.

[0032] By incorporating a purging assembly, the absorption interference from stray gases in the environment at both the transmitter and receiver ends is resolved, thereby improving the accuracy of spectral parameter measurements.

[0033] By setting up a first vacuum pump and a purging assembly at the light guide tube, the absorption interference of stray gases in various stages of the calibration device is eliminated, achieving low-background target gas absorption and improving the measurement accuracy of spectral parameters.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of an absorption spectroscopy calibration device according to an embodiment of the present invention is shown;

[0037] Figure 2 A schematic diagram of the purge assembly near the transmitting unit is shown in an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of the purge assembly near the receiving unit according to an embodiment of the present invention is shown;

[0039] Figure 4 A schematic diagram of the structure near the light guide tube end of the emitting unit is shown in an embodiment of the present invention;

[0040] Figure 5 A schematic diagram of the structure of the light guide tube end near the receiving unit is shown in an embodiment of the present invention;

[0041] Figure 6 A schematic diagram of the furnace tube according to an embodiment of the present invention is shown;

[0042] In the diagram: 10. Absorption spectrometer; 11. Transmitting unit; 12. Receiving unit; 20. Purge assembly; 21. Gas cylinder; 22. First-stage sealed chamber; 23. Second-stage sealed chamber; 30. Adjustment frame; 40. Light guide assembly; 41. First vacuum pump; 42. Atmosphere generating assembly; 43. First water-cooled flange; 44. First sealing ring; 45. First window; 46. Second water-cooled flange; 47. Third water-cooled flange; 48. Light guide tube; 49. Second window; 410. Second vacuum pump; 50. Furnace tube; 51. Isostatic zone; 52. Heating zone; 53. Thermocouple; 60. Pressure gauge. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown, an absorption spectrum calibration device according to certain embodiments of the present invention includes a furnace tube 50 and light guide assemblies 40 symmetrically arranged at both ends of the furnace tube 50;

[0045] The light guide assembly 40 includes a light guide tube 48 and a window that is sealed at both ends of the light guide tube 48. One end of the light guide tube 48 extends into the cavity of the furnace tube 50 and is suspended in the middle region of the cavity. The other end of the light guide tube 48 is located outside the furnace tube 50.

[0046] The absorption spectrometer 10 includes an emitting unit 11 and a receiving unit 12. The light generated by the emitting unit 11 is transmitted to the cavity of the furnace tube 50 through the light guide tube 48 at one end of the furnace tube 50, and then transmitted to the receiving unit 12 through the light guide tube 48 at the other end of the furnace tube 50, forming a complete absorption spectrum calibration optical path.

[0047] The cavity of the furnace tube 50 serves as the calibration environment for the spectrometer. Filling the cavity of the furnace tube 50 with gas and heating the cavity of the furnace tube 50 are ways to set the temperature and standard atmosphere for the calibration environment of the spectrometer.

[0048] The light guide assembly 40 is used to provide the vacuum transmission optical path calibrated by the absorption spectrometer 10;

[0049] The light guide component 40 uses a light guide tube 48 to guide light. Compared with the traditional solid rod-shaped guide tube, the length of the light-structure interaction is greatly shortened, which improves the light transmittance in the mid-infrared band and solves the problem that ordinary devices cannot be used for the calibration of the mid-infrared absorption spectrometer 10.

[0050] By using a light guide tube 48 with sealed connections at both ends, a sealed light guide tube 48 is achieved, thus solving the sealing problem of the light guide tube 48.

[0051] like Figure 2 As shown, in some embodiments of the present invention, the end of the light guide component 40 located outside the furnace tube 50 is provided with a purging component 20;

[0052] The purging assembly 20 includes a first-stage sealed box 22 and a second-stage sealed box 23, with the first-stage sealed box 22 located inside the second-stage sealed box 23.

[0053] In some embodiments of the present invention, the first-stage sealed box 22 is used to house the transmitting unit 11, such as... Figure 2 As shown.

[0054] In some embodiments of the present invention, the first-stage sealed box 22 is used to house the receiving unit 12, such as... Figure 3 As shown.

[0055] In some embodiments of the present invention, the first-stage sealed box 22 is provided with an air inlet pipe and an air outlet. The air inlet pipe penetrates the box wall of the second-stage sealed box 23 and extends to the outside of the second-stage sealed box 23. The box wall of the first-stage sealed box 22 with the air inlet pipe is far away from the transmitting unit 11 or the receiving unit 12.

[0056] The second-stage sealed box 23 is equipped with an air outlet;

[0057] The air inlet pipe is used to provide a channel for the purge air source to directly enter the first-stage sealed box 22, and then enter the second-stage sealed box 23 through the air outlet on the first-stage sealed box 22.

[0058] The placement of the first-stage sealed box 22 with the air inlet pipe away from the transmitting unit 11 or the receiving unit 12 facilitates the slow filling of the first-stage sealed box 22 with the gas purged from the purge gas source, thereby reducing the impact of the gas purged from the purge gas source (such as low-temperature nitrogen) on the transmitting unit 11 or the receiving unit 12.

[0059] The air outlet is used to provide a channel for the purge air source to be discharged from the first-stage sealed box 22 and the first-stage sealed box 22;

[0060] The arrangement of the first-stage sealed box 22 and the second-stage sealed box 23 ensures the secondary sealing effect of the purging assembly 20 and avoids the following situation: during the purging process, due to poor sealing, air enters the first-stage sealed box 22 and becomes stray gas in the gap between the transmitting unit 11 or the receiving unit 12 and the first window 45, thereby affecting the transmitting signal or receiving signal and causing inaccurate calibration.

[0061] In some embodiments of the present invention, the first-stage sealed box 22 is connected to a purge gas source, such as a gas cylinder 21, which stores high-purity nitrogen.

[0062] The gas supplied by the purge gas source enters the first-stage sealed box 22 through the air inlet pipe, purging the first-stage sealed box 22 and the second-stage sealed box 23. With continuous purging, the purge gas source completely fills the first-stage sealed box 22 and the second-stage sealed box 23. At the same time, it fills the gap between the second-stage sealed box 23 and the window (i.e., the first window 45) at the end of the light guide tube 48 (the gap caused by the aging or loosening of the first sealing ring 44 at the connection between the second-stage sealed box 23 and the first window 45), so as to eliminate the absorption interference of stray gas in the gap between the transmitting unit 11 or the receiving unit 12 and the first window 45.

[0063] like Figure 4 As shown, in some embodiments of the present invention, the window near the transmitting unit 11 is a first window 45, and the first window 45 is located between the second-level sealed box 23 and the light guide tube 48;

[0064] The second-stage sealed box 23 is sealed with a first water-cooled flange 43, and the second-stage sealed box 23 is pressed and connected to the first window 45 through the first water-cooled flange 43;

[0065] The end of the light guide tube 48 is sealed with a second water-cooled flange 46, and the light guide tube 48 is pressed and connected to the first window 45 through the second water-cooled flange 46.

[0066] In some embodiments of the present invention, the second-stage sealed box 23 and the first water-cooled flange 43 are sealed together by a first sealing ring 44.

[0067] In some embodiments of the present invention, the light guide tube 48 and the second water-cooled flange 46 are sealed together by a first sealing ring 44.

[0068] In some embodiments of the present invention, a channel is provided on the second water-cooled flange 46, the channel is connected to a first vacuum pump 41, and the first vacuum pump 41 is connected to the light guide tube 48 through the channel.

[0069] The second water-cooled flange 46 not only serves to water-cool the first window 45 and press the first window 45, but also serves to connect the first vacuum pump 41.

[0070] The first vacuum pump 41 is used to evacuate the light guide tube 48. At the same time, during the evacuation process, the gap between the light guide tube 48 and the first window 45 (the gap caused by the aging or loosening of the first sealing ring 44 at the connection between the light guide tube 48 and the first window 45) is also evacuated to eliminate the interference of light absorption by stray gas in the light guide tube 48.

[0071] The compression and sealing connection between the first window 45 and the light guide tube 48 not only solves the sealing problem at one end of the light guide tube 48, but also takes into account the high calibration accuracy of the calibration device, which requires a vacuuming operation on the light guide tube 48. Therefore, the second water-cooled flange 46, which is connected by compression and sealing, serves as a component connecting the first vacuum pump 41 and the light guide tube 48, thus ensuring both the sealing and vacuuming effects of the light guide tube 48.

[0072] like Figure 4 As shown, in some embodiments of the present invention, a third water-cooled flange 47 is provided at the connection between the light guide tube 48 and the furnace tube 50;

[0073] A second sealing ring is provided inside the third water-cooled flange 47, and the light guide tube 48 and the furnace tube 50 are sealed together through the third water-cooled flange 47 and the second sealing ring.

[0074] like Figure 4 As shown, in some embodiments of the present invention, the third water-cooled flange 47 near the launching unit 11 is connected to an atmosphere generating assembly 42;

[0075] The atmosphere generating component 42 is connected to the furnace tube 50 and is used to inject a target gas of standard concentration into the cavity of the furnace tube 50 to provide a calibration atmosphere for the calibration device.

[0076] like Figure 5 As shown, in some embodiments of the present invention, the third water-cooled flange 47 near the receiving unit 12 is connected to a second vacuum pump 410;

[0077] A pressure gauge 60 is also provided on the third water-cooled flange 47 near the receiving unit 12;

[0078] The second vacuum pump 410 is connected to the furnace tube 50 and serves to remove stray gases from the cavity of the furnace tube 50.

[0079] The pressure gauge 60 is used to detect the pressure inside the furnace tube 50 cavity.

[0080] In some embodiments of the present invention, the window located inside the furnace tube 50 is a second window 49, and the second window 49 and the light guide tube 48 are sealed together by an ultra-smooth surface bonding process.

[0081] In some embodiments of the present invention, the light guide tube 48 and the window are both made of sapphire to adapt to the high temperature setting of the furnace tube 50.

[0082] In some embodiments of the present invention, a resistance wire and several thermocouples 53 are arranged in the inner cavity of the furnace tube 50;

[0083] The setting of the resistance wire facilitates heating of the inner cavity of the furnace tube 50, and the setting of several thermocouples 53 facilitates monitoring the temperature of multiple areas of the inner cavity of the furnace tube 50.

[0084] like Figure 6 As shown, in the inner cavity of the furnace tube 50, a uniform temperature zone 51 is formed between the second window 49 on the light guide tube 48 near the transmitting unit 11 and the second window 49 on the light guide tube 48 near the receiving unit 12. The remaining space in the inner cavity of the furnace tube 50 is a heating zone 52. Thermocouples are provided in the uniform temperature zone 51 and the heating zone 52.

[0085] The temperature equalization zone 51 is provided with at least two thermocouples 53, which are distributed on both sides of the temperature equalization zone 51.

[0086] For example, there are three thermocouples 53. One thermocouple 53 is arranged in the temperature uniform zone 51, and the remaining two thermocouples 53 are arranged on both sides of the temperature uniform zone 51, located in the heating zone 52.

[0087] In some embodiments of the present invention, both the transmitting unit 11 and the receiving unit 12 are provided with an adjustment bracket 30 at their bottom;

[0088] The adjustment frame 30 is located at the bottom of the first-stage sealed box 22 and is used to support the transmitting unit 11 and receiving unit 12 of the absorption spectrometer 10, and also to adjust the optical path.

[0089] When performing optical path alignment optimization, it is necessary to meet the requirements of the absorption spectroscopy temperature detection equipment for received light intensity or signal-to-noise ratio. When using fiber optic transmission, visible light output from the fiber can be used to assist alignment; when using spatial transmission, the output light source of the absorption spectroscopy temperature detection equipment can be adjusted to ensure that the indicated visible light is combined with the optical path before entering the furnace tube 50. When debugging the light source of the absorption spectroscopy temperature detection equipment, a photosensitive plate is used to assist in observing the position of the light spot in the non-visible band. Ensure that the light from the transmitting unit 11 completely passes through the light guide assembly 40 and can be received by the receiving unit 12.

[0090] The atmosphere generating component 42 in the above embodiments is a gas generating device commonly used in this technical field or a gas cylinder 21 storing standard gas, which will not be described in detail here.

[0091] A calibration method for an absorption spectral calibration device according to an embodiment of the present invention includes:

[0092] S1. Heat the furnace tube 50 until the temperature of the sealed cavity of the furnace tube 50 reaches the preset temperature;

[0093] S2. Vacuum and gas purging are performed on furnace tube 50. After vacuuming and gas purging are completed, vacuuming is performed on light guide component 40.

[0094] S3. Fill the sealed cavity of furnace tube 50 with standard atmosphere until the predetermined pressure is reached. Wait for a period of time and observe the temperature and pressure changes inside furnace tube 50 during the first period of time. When the temperature and pressure changes inside furnace tube 50 reach the calibration conditions, the absorption spectrum calibration at the preset temperature is completed.

[0095] In some embodiments of the present invention, the calibration conditions are: the furnace temperature deviates from the preset temperature point by no more than ±1℃, and the furnace temperature change does not exceed 0.2℃ / min, and the pressure gauge 60 change does not exceed 1Pa / min.

[0096] In some embodiments of the present invention, a purging step is further included between step S2 and step S3, including:

[0097] Open the purging assembly 20 to purge the first-stage sealed box 22 and the second-stage sealed box 23 where the emitting unit 11 and the receiving unit 12 of the spectrum are located, so as to eliminate the absorption interference of stray gas in the gap between the emitting unit 11, the receiving unit 12 and the sapphire window.

[0098] In some embodiments of the present invention, in step S2, during the gas washing process, high-purity nitrogen gas is introduced using the atmosphere generating component 42 as the gas source for the washing gas.

[0099] In some embodiments of the present invention, the calibration method of the calibration device includes:

[0100] (1) Heat the furnace tube 50 of the calibration device to the preset temperature and use a thermocouple to detect the temperature. After a period of stabilization, a high-temperature uniform temperature zone 51 is formed between the two sapphire tubes.

[0101] (2) Evacuate the temperature uniform zone 51 of the furnace tube 50 to below 10 Pa, and close the gas extraction valve; open the gas inlet valve and use the atmosphere generator to fill the gas with high-purity nitrogen to 0.1 MPa, close the gas inlet valve, stabilize for 1 min, open the gas extraction valve, and then perform vacuuming again. Use nitrogen to wash the gas twice to eliminate the interference of adsorbed gas.

[0102] (3) After the nitrogen gas washing is completed, the vacuum is evacuated to below 10 Pa, the target gas is introduced to 0.1 MPa, the inlet valve is closed, the gas is stabilized for 1 min, the gas extraction valve is opened, and the vacuum is evacuated again. The gas washing is repeated twice with the target gas to stabilize the gas concentration of the target gas.

[0103] (4) Turn on the vacuum pump on the light guide assembly 40 and evacuate to below 10Pa to eliminate the absorption interference of stray gas in the light guide tube 48; open the peripheral air purging valve between the window and the transmitting unit 11 and between the window and the receiving unit 12, and purge with high-purity nitrogen to eliminate the absorption interference of stray gas in the gap between the transmitting unit 11, the receiving unit 12 and the sapphire window.

[0104] (5) When the target gas is introduced into the uniform temperature zone 51 of the furnace tube 50 and reaches the near-predetermined pressure, close the gas inlet valve, then close the corresponding gas cylinder 21 and pipeline valve / switch, wait for 30 minutes, and when the furnace temperature deviates from the set temperature point by no more than ±1℃, and the furnace temperature change does not exceed 0.2℃ / min, and the pressure gauge 60 change does not exceed 1Pa / min, start collecting data and collect N sets of data, where N≥6;

[0105] (6) After completing the first temperature calibration point, you can skip to the next heating / cooling program and repeat steps (2) to (4) until all selected temperature range calibration points are tested;

[0106] (7) After calibration, shut down the equipment according to the requirements of the absorption spectrum temperature detection equipment.

[0107] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An absorption spectrum calibration device, characterized in that, It includes a furnace tube (50) and light guide assemblies (40) symmetrically arranged at both ends of the furnace tube (50); The light guide assembly (40) includes a light guide tube (48) and a window that is sealed at both ends of the light guide tube (48). One end of the light guide tube (48) extends into the cavity of the furnace tube (50) and is suspended in the middle area of ​​the cavity. The other end of the light guide tube (48) is located outside the furnace tube (50). The light guide assembly (40) is used to provide a vacuum transmission optical path for the spectral instrument calibration.

2. The absorption spectrum calibration device according to claim 1, characterized in that, The light guide component (40) is provided with a purging component (20) at the end outside the furnace tube (50); The purging assembly (20) includes a first-stage sealed box (22) and a second-stage sealed box (23), wherein the first-stage sealed box (22) is located inside the second-stage sealed box (23); The first-stage sealed box (22) is used to house the transmitting unit (11) or receiving unit (12) of the absorption spectrometer (10). The first-stage sealed box (22) is provided with an air inlet pipe and an air outlet. The air inlet pipe penetrates the wall of the second-stage sealed box (23) and extends to the outside of the second-stage sealed box (23). The second-stage sealed box (23) is provided with an air outlet.

3. The absorption spectrum calibration device according to claim 2, characterized in that, The window near the transmitting unit (11) is the first window (45), which is located between the second-level sealed box (23) and the light guide tube (48). The second-stage sealed box (23) is sealed with a first water-cooled flange (43), and the second-stage sealed box (23) is pressed and connected to the first window (45) through the first water-cooled flange (43); The end of the light guide tube (48) is sealed with a second water-cooled flange (46), and the light guide tube (48) is pressed and connected to the first window (45) through the second water-cooled flange (46).

4. The absorption spectrum calibration device according to claim 3, characterized in that, A channel is provided on the second water-cooled flange (46), and the channel is connected to a first vacuum pump (41). The first vacuum pump (41) is connected to the light guide tube (48) through the channel.

5. The absorption spectrum calibration device according to claim 1, characterized in that, A third water-cooled flange (47) is provided at the connection between the light guide tube (48) and the furnace tube (50).

6. The absorption spectrum calibration device according to claim 5, characterized in that, The third water-cooled flange (47) near the launching unit (11) is connected to an atmosphere generating assembly (42), which is connected to the furnace tube (50); The third water-cooled flange (47) near the receiving unit (12) is connected to a second vacuum pump (410), which is connected to the furnace tube (50). A pressure gauge (60) is also provided on the third water-cooled flange (47) near the receiving unit (12).

7. The absorption spectrum calibration device according to claim 1, characterized in that, The window located inside the furnace tube (50) is the second window (49), and the second window (49) and the light guide tube (48) are sealed together by an ultra-smooth surface bonding process.

8. The absorption spectrum calibration device according to claim 1, characterized in that, The light guide tube (48) and the window are both made of sapphire. The furnace tube (50) has a resistance wire and several thermocouples (53) arranged inside its cavity.

9. The absorption spectrum calibration device according to claim 1, characterized in that, It also includes an absorption spectrometer (10), which includes a transmitting unit (11) and a receiving unit (12), and both the transmitting unit (11) and the receiving unit (12) are provided with an adjustment frame (30) at the bottom.

10. A method for calibrating absorption spectra based on the absorption spectral calibration device according to any one of claims 1-9, characterized in that, include: The furnace tube (50) is heated until the temperature of the sealed cavity of the furnace tube (50) reaches the preset temperature; Vacuuming and purging of the furnace tube (50); after completing the vacuuming and purging, vacuuming of the light guide component (40); A standard atmosphere is introduced into the sealed cavity of the furnace tube (50) until the predetermined pressure is reached. After waiting for a period of time, the temperature and pressure changes inside the furnace tube (50) are observed. When the temperature and pressure changes inside the furnace tube (50) reach the calibration conditions, the absorption spectrum calibration at the preset temperature is completed.

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