Fourier infrared light path system

Abstract

A Fourier infrared light path system disclosed by the present invention comprises a light source, a coupling light path, a gas chamber and an infrared detector, a first reflector, a second reflector and a third reflector are installed in the gas chamber, and light beams of the coupling light path form eight first light spots on the mirror surface of the third reflector after being reflected by the first reflector. According to the invention, the path of the light path in the third reflector is designed to be distributed in an upper-seven-lower-eight mode, so that when the gas chamber is replaced, only the first reflector and the second reflector need to be adjusted, and the light path can be replaced, so that the light path can be replaced. The path of the light path in the third reflecting mirror returns to seven-up eight-down distribution again, so that the light path after the gas chamber is replaced is consistent, meanwhile, the light path has the effect of large light path in the gas chamber, and the precision of an instrument is improved.

Description

Technical Field

[0001] The present invention relates to an optical technology, in particular to a Fourier infrared optical path system. Background Art

[0002] Fourier transform infrared spectroscopy (FTIR) can measure spectra ranging from a few microns to more than ten microns. Each absorption peak in the spectrum corresponds to the vibration frequency of a specific chemical bond or functional group in the sample. By analyzing the position, intensity, and shape of these absorption peaks, the presence of chemical bonds, functional groups, and their relative abundance can be inferred. FTIR technology is widely used in chemistry, physics, biology, pharmacy, and environmental monitoring. The main components of an FTIR system are an interferometer, a light source, and a sample chamber. For a Fourier transform infrared gas analyzer, the sample chamber serves as both the gas chamber and the White cell. The optical pathlength of the White cell directly affects the measured gas concentration. Gas concentration is then calculated using the same set of standard spectra. Poor consistency between the gas chambers, resulting in different optical pathlengths, can lead to deviations in gas concentration measurements. Furthermore, when Fourier transform infrared equipment is used in flue gas monitoring applications, corrosive gases or improper on-site operation can reduce the reflectivity of the gas chamber's lenses, resulting in reduced light intensity and making it unsuitable for measurement. This necessitates replacement of the gas chamber, which must maintain the same optical pathlength as the previous one. Two factors influence the optical path length of the gas cell: the angle of the two small reflectors, and the angle of the incident light, or the angle of the infrared light entering the gas cell. The current gas cell positioning method uses single-unit debugging, meaning the coupled optical cell and gas cell are aligned one-to-one. This can cause the optical path length to change after replacing the gas cell. Furthermore, transport vibrations can cause the angle of the small reflectors within the gas cell to shift, necessitating increased reliability in securing the small reflectors. Summary of the Invention

[0003] In order to solve the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a Fourier infrared optical path system, which can ensure the consistency of the optical path after replacing the gas chamber and at the same time increase the optical path.

[0004] The technical solution adopted by the present invention to solve its technical problem is: a Fourier infrared optical path system, including a light source, a coupling optical path, an air chamber and an infrared detector; wherein a first reflector, a second reflector and a third reflector are installed in the air chamber, the first reflector and the second reflector are arranged in the same row, and the first reflector and the second reflector have the same structure and specifications, and the third reflector is arranged on the opposite side of the first reflector and the second reflector, so that the light beam reflected by the first reflector is reflected to the third reflector, and the light beam reflected by the third reflector is then reflected to the second reflector;

[0005] The first reflector, the second reflector, and the third reflector are all concave mirrors, and the first reflector, the second reflector, and the third reflector have the same curvature radius, so that the light beam of the coupled optical path, after being reflected by the first reflector for the first time, just falls on the first edge position of the third reflector, and then returns to the first reflector after being reflected by the third reflector; the light beam, after being reflected by the first reflector for the last time, falls on the second edge position of the third reflector, and then enters the second reflector after being reflected by the third reflector; the light beam, after being reflected by the second reflector for the first time, just falls on the third edge position of the third reflector; and the light beam, after being reflected by the second reflector for the last time, exits the gas chamber;

[0006] There is an interlaced angle between the first reflector and the second reflector, so that after the light beam is reflected by the first reflector, eight first light spots are formed on the mirror surface of the third reflector, and after the light beam is reflected by the second reflector, seven second light spots are formed on the mirror surface of the third reflector, and the second light spots are located above the first light spots.

[0007] Optionally, the first reflector includes a base, a mirror body, a pressure ring, a corrugated washer, a gasket, a screw and a top screw. The mirror body is installed in the base through the pressure ring, screws and top screws. The corrugated washer and gasket are also provided between the mirror body and the base.

[0008] Optionally, the gasket is wedge-shaped.

[0009] Optionally, an outer ring of the third reflector is provided with an identification piece, and a small hole is provided in the identification piece.

[0010] Optionally, the light source is made of silicon carbide, and the light emitting band of the light source is 2~14um.

[0011] The present invention employs the above-described technical solution, employing a first reflector, a second reflector, and a third reflector to design the optical path through the third reflector into a seven-up, eight-down pattern. When replacing the air chamber, simply adjusting the first and second reflectors to return the optical path through the third reflector to the seven-up, eight-down pattern ensures a consistent optical path after replacing the air chamber. Furthermore, the optical path of the present invention has a longer optical path within the air chamber, thereby improving the accuracy of the instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the optical path system structure of the present invention;

[0013] Figure 2 is a schematic structural diagram of the first reflector of the present invention;

[0014] Figure 3 Schematic diagram of the distribution of the first reflector, the second reflector, and the third reflector in the air chamber of the present invention;

[0015] Figure 4 It is a schematic structural diagram of the third reflector of the present invention. DETAILED DESCRIPTION

[0016] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0017] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] like Figure 1 As shown, the present invention discloses a Fourier infrared optical path system, including a light source 1, a coupling optical path, a gas chamber 2 and an infrared detector 3. Among them, the light source 1 is an infrared light source, and its material can be made of silicon carbide material, and the light emission band is 2~14um. The coupling optical path is the optical path of the Fourier infrared interferometer, wherein the coupling optical path includes an infrared interference optical path and a laser interference optical path. Various optical path elements for transmitting light beams are provided in the optical path system. The light source 1 can emit infrared divergent light, and the infrared divergent light propagates in the optical path elements and forms interference light. The interference light is irradiated into the sample and finally received by the infrared detector 3. In addition, the laser light source in the laser interference optical path emits laser light with a wavelength of 500~850nm. The optical path elements in the infrared interference optical path include a first off-axis parabolic mirror 4, a beam splitter 5, a first plane reflector 6, a first corner mirror 7, a second plane reflector 8, a second corner mirror 9, a second off-axis parabolic mirror 10 and a third plane reflector 11, wherein the off-axis angle of the first off-axis parabolic mirror 4 is 60°, the off-axis angle of the second off-axis parabolic mirror 10 is 90°, and the focal length of both is 33 mm. The infrared light beam emitted by light source 1 is reflected and collimated by first off-axis parabolic mirror 4 and then transmitted to beam splitter 5. Beam splitter 5 splits the infrared light into transmitted light and reflected light. The reflected light passes through first plane reflector 6 and first angle mirror 7 and returns to beam splitter 5. The transmitted light passes through second plane reflector 8 and second angle mirror 9 and returns to beam splitter 5. The transmitted and reflected light interfere with each other when returning to beam splitter 5 to form interference light, which is then transmitted to second off-axis parabolic mirror 10. The interference light converges after second off-axis parabolic mirror 10 to form a light spot and is emitted to third plane reflector 11. Third plane reflector 11 reflects the light beam into gas chamber 2. In the present invention, beam splitter 220 includes two working areas: the first working area is used to reflect and transmit infrared light, and the second working area is used to reflect and transmit laser light. In addition, in the present invention, laser light source 12 in the laser interference optical path emits a laser beam of 500-850nm. After interference through an interference path similar to the infrared interference optical path, it is received by laser detector 13.

[0019] In the present invention, the first and second prisms 7 and 9 are fixed to the bracket via voice coil motors. These motors respectively drive the first and second prisms 7 and 9 to rotate, thereby creating an optical path difference between the reflected and transmitted light, resulting in the output of interference light. Furthermore, a compensating sheet is attached to the beam splitter 5 on the side closest to the first plane reflector 6 and first prism 7, providing phase compensation.

[0020] In the present invention, a first reflector 14, a second reflector 15, and a third reflector 16 are installed in the air chamber 2. The first reflector 14 and the second reflector 15 are arranged in the same row. The first reflector 14 and the second reflector 15 have the same structure and specifications. The width of the first reflector 14 and the second reflector 15 is smaller than the width of the third reflector 16. In one embodiment of the present invention, the sum of the widths of the first reflector 14 and the second reflector 15 can be set to be equal to the width of the third reflector 16. The third reflector 16 is arranged on the opposite side of the first reflector 14 and the second reflector 15, so that the light beam reflected by the first reflector 14 is reflected to the third reflector 16, and the light beam reflected by the third reflector 16 is then reflected to the second reflector 15, and finally emitted from the air chamber 2 through the second reflector 15.

[0021] In the present invention, the first reflector 14, the second reflector 15, and the third reflector 16 are all concave mirrors, and the curvature radius of the first reflector 14, the second reflector 15, and the third reflector 16 are the same. For example, the curvature radius of the three is 150 mm. The light beam in the coupled optical path, after the first reflection by the first reflector 14, falls exactly on the first edge position of the third reflector 16. Then, it is reflected by the third reflector 16 and returns to the first reflector 14. After the final reflection by the first reflector 14, the light beam falls on the second edge position of the third reflector 16. Then, it is reflected by the third reflector 16 and enters the second reflector 15. Then, after the first reflection by the second reflector 15, the light beam falls exactly on the third edge position of the third reflector 16. After the final reflection by the second reflector 15, the light beam exits the gas chamber. The first edge position is symmetrically distributed with the second edge position, and the third edge position is located above the first edge position.

[0022] In the present invention, there is an interlaced angle between the first reflector 14 and the second reflector 15, so that the light beam forms eight first light spots on the mirror surface of the third reflector 16 after being reflected by the first reflector 14, and forms seven second light spots on the mirror surface of the third reflector 16 after being reflected by the second reflector 15, and the second light spots are located above the first light spots. Figure 4As shown, in order to ensure that the light spots are arranged in an order of seven at the top and eight at the bottom each time, an identification plate 17 can be provided on the outer ring of the third reflector 16, and a small hole can be provided in the identification plate 17. The small hole is used for the light beam reflected by the first reflector 14 to reach the first edge position after passing through. The position of the small hole is determined by forming eight first light spots in the third reflector 16 after the first reflector 14 is debugged for positioning. The position is then fixed by the identification plate 17. In subsequent debugging, it is only necessary to hit the light beam reflected by the first reflector 14 into the small hole. Figure 3 and Figure 4 As shown, when adjusting the interleaving angle between the first reflector 14 and the second reflector 15, the HeNe laser 18 is used as an indicator, and the output light beam of the HeNe laser 18 is adjusted to be emitted along the light path reflected by the third plane reflector 11, and then the first reflector 14 is adjusted so that the light beam reflected by the first reflector 14 hits the small hole, and then the inclination angle of the second reflector and the angle between the second reflector and the first reflector 14 are adjusted so that seven second light spots are formed on the third reflector 16.

[0023] In the present invention, the first reflector 14 and the second reflector 15 have the same structure. Taking the first reflector 14 as an example, the components of the two will be described.

[0024] like Figure 2 As shown, the first reflector 14 includes a base 19, a mirror body 20, a pressure ring 21, a corrugated washer 22, a gasket 23, a screw 24 and a top screw 25. The mirror body 20 is installed in the base 19 through the pressure ring 21 and the top screw 24. A corrugated washer 22 and a gasket 23 are also provided between the mirror body 20 and the base 19. The gasket 23 is wedge-shaped to leave adjustment space for the mirror body 20. The pressure ring 21 has three threaded holes and three through holes, which are respectively used to connect the top screw 25 and the screw 24. The corrugated washer 22 is used to provide adjustment space for the mirror body 20. In order to enhance stability, the greater the compression of the corrugated washer 22 by the mirror body 20, the more stable it is. Therefore, a gasket 23 is added between the corrugated washer 22 and the base 19. The gasket 23 has a wedge angle, is thick at the top and thin at the bottom, is 2.58mm thick at the top and 0.33mm thick at the bottom. Because when the mirror body 20 is adjusted, the adjustment amount at the bottom is larger, and the compression amount of the corrugated washer 22 is larger. The middle of the gasket 23 protrudes from a table with a diameter of 25mm and a thickness of 0.5mm, which is used to limit the corrugated gasket 22 and prevent the corrugated gasket 22 from shifting. There is a through hole in the center of the table, and the gasket is fixed to the base 19 with a flat head screw. The screw 24 passes through the pressure ring 21 and the gasket 23 and is fixed in the threaded hole of the base 19. By adjusting the three screws 24, the angle of the mirror body 20 can be changed, thereby changing the position of the light spot. After adjusting the position, use the top screw 25 to pass through the pressure ring 21 and support the gasket 23 to fix the position of the pressure ring 21.

[0025] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

[0026] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A Fourier infrared optical system, characterized in that: The invention comprises a light source, a coupling optical path, an air chamber, and an infrared detector; wherein a first reflector, a second reflector, and a third reflector are installed in the air chamber, the first reflector and the second reflector are arranged in the same row, and the first reflector and the second reflector have the same structure and specifications, and the third reflector is arranged on the opposite side of the first reflector and the second reflector, so that the light beam reflected by the first reflector is reflected to the third reflector, and the light beam reflected by the third reflector is then reflected to the second reflector; The first reflector, the second reflector, and the third reflector are all concave mirrors, and the first reflector, the second reflector, and the third reflector have the same curvature radius, so that the light beam of the coupled optical path, after being reflected by the first reflector for the first time, just falls on the first edge position of the third reflector, and then returns to the first reflector after being reflected by the third reflector; the light beam, after being reflected by the first reflector for the last time, falls on the second edge position of the third reflector, and then enters the second reflector after being reflected by the third reflector; the light beam, after being reflected by the second reflector for the first time, just falls on the third edge position of the third reflector; and the light beam, after being reflected by the second reflector for the last time, exits the gas chamber; There is an interlaced angle between the first reflector and the second reflector, so that after the light beam is reflected by the first reflector, eight first light spots are formed on the mirror surface of the third reflector, and after the light beam is reflected by the second reflector, seven second light spots are formed on the mirror surface of the third reflector, and the second light spots are located above the first light spots.

2. The Fourier infrared optical path system according to claim 1, characterized in that: The first reflector includes a base, a mirror body, a pressure ring, a corrugated washer, a gasket, a screw and a top screw. The mirror body is installed in the base through the pressure ring, screws and top screws. The corrugated washer and gasket are also provided between the mirror body and the base.

3. The Fourier infrared optical path system according to claim 2, characterized in that: The shape of the gasket is wedge-shaped.

4. The Fourier infrared optical path system according to claim 3, characterized in that: An outer ring of the third reflector is provided with an identification piece, and a small hole is provided in the identification piece.

5. The Fourier infrared optical path system according to claim 1, characterized in that: The light source is made of silicon carbide, and the light emission wavelength range of the light source is 2-14 μm.

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