Multi-reflection cell, analysis device and analysis method

Abstract

To achieve a short optical path with a reduced number of reflections of laser light without significantly changing the design of a multiple reflection cell, such as the optical system, the light transmission window, the cell length and / or the cell volume.SOLUTION: A multiple reflection cell, in which a sample is introduced into an internal space and light is reflected in the internal space, comprises a light-transmitting window that allows light to enter the internal space and exit the internal space, and a reflection mechanism that is provided in the internal space and causes the light entering through the light-transmitting window to be reflected multiple times by the reflective surfaces of multiple plane mirrors and then exited from the light-transmitting window.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a multi-reflection cell, an analyzer, and an analysis method.

Background Art

[0002] Conventional multi-reflection cells include, for example, as shown in Patent Document 1, a cell body into which a sample gas is introduced into an internal space, and a pair of mirrors provided facing the internal space, and laser light incident from an incident window of the cell body is multi-reflected between the pair of mirrors several tens to several hundreds of times and then emitted from an emission window of the cell body. By multi-reflecting between the pair of mirrors in this way, the optical path length becomes longer (that is, a long optical path is achieved), so the distance over which the laser light and the sample gas interact can be increased, and the sensitivity can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in such a multi-reflection cell, when the concentration of the component to be measured is high, if the measurement is performed with a long optical path, the concentration will saturate. Therefore, it is necessary to suppress the number of reflections of the laser light and realize a short optical path with a short optical path length. However, in the case of a short optical path, it was necessary to remake the optical system including the light emitting part and the light detecting part, the light transmission window, the cell length, and / or the cell volume for the short optical path.

[0005] Therefore, the present invention has been made in view of the above-described problems, and its main object is to realize a short optical path with the number of reflections of the laser light suppressed without significantly changing the design of the multi-reflection cell such as the optical system, the light transmission window, the cell length, and / or the cell volume.

Means for Solving the Problem

[0006] That is, the multi-reflection cell according to the present invention is a multi-reflection cell in which a sample is introduced into an internal space and light is reflected in the internal space, and includes a light transmission window for incident light into the internal space and emitting light from the internal space, and a reflection mechanism provided in the internal space for reflecting light incident from the light transmission window a plurality of times by the reflection surfaces of a plurality of planar mirrors and then emitting the light from the light transmission window.

[0007] In such a multi-reflection cell, since the reflection mechanism reflects light a plurality of times by the reflection surfaces of a plurality of planar mirrors and then emits the light toward the light transmission window, the incident and emission of light can be made through the same light transmission window. As a result, a short optical path with a small number of reflections can be realized without significantly changing the design of the multi-reflection cell. Here, the short optical path means an optical path in the internal space with a smaller number of reflections than the long optical path. In addition, since the reflection mechanism uses a plurality of planar mirrors when reflecting light a plurality of times, compared with the case of using other shaped mirrors, it is easier to adjust the direction in which light is reflected, and the optical design of the internal space can be simplified. Here, the optical design of the internal space refers to the arrangement of the mirrors and the selection of the types of mirrors when light incident from the light transmission window is reflected a plurality of times in the internal space and then emitted from the same light transmission window.

[0008] As a specific embodiment for realizing a short optical path, the reflection mechanism preferably has a first planar mirror and a second planar mirror provided in the internal space opposite to the light transmission window, the first planar mirror reflects light incident from the light transmission window toward the second planar mirror, and the second planar mirror reflects the light reflected by the first planar mirror toward the light transmission window.

[0009] With such a configuration, the first planar mirror reflects the light incident from the light transmission window toward the second planar mirror, and the second planar mirror reflects the light reflected by the first planar mirror toward the light transmission window. Therefore, it is possible to realize a short optical path of two reflections in the case where the light incident and emitted is the same light transmission window. In addition, since a short optical path of two reflections can be realized only with two planar mirrors, the optical design of the internal space can be further simplified, and the sensitivity in the case of measuring a high-concentration measurement target component, which is a measurement target component preferably analyzed with a short optical path length, can be improved.

[0010] Preferably, the reflection mechanism further includes a connecting portion that connects the first planar mirror and the second planar mirror in a state where the reflection surfaces of the first planar mirror and the second planar mirror face each other.

[0011] With such a configuration, since the first planar mirror and the second planar mirror are connected by the connecting portion and the reflection mechanism has an integrated structure, the reflection mechanism can be easily installed in the internal space as compared with the case where the first planar mirror and the second planar mirror are separate.

[0012] In order to further simplify the optical design of the internal space and facilitate miniaturization of the multiple reflection cell, it is preferable that the first planar mirror and the second planar mirror are provided symmetrically with respect to a central axis that is an axis passing through the center of the light transmission window in the internal space.

[0013] Preferably, the reflection mechanism further includes a pair of mirrors provided to face each other in the internal space, and the pair of mirrors includes one mirror in which the light transmission window is formed and the other mirror that emits light to the light transmission window after multiple-reflecting the light incident from the light transmission window between the one mirror.

[0014] With such a configuration, in addition to forming a short optical path in the internal space by means of a planar mirror, the reflection mechanism multiplies the reflection of light between a pair of mirrors, so that the optical path length in the internal space can be increased. Therefore, by simply changing the type of mirror that reflects light according to the length of the optical path, either a short optical path length or a long optical path length can be realized in the internal space of the same multiple reflection cell. In addition, even when both the light with a long optical path and the light with a short optical path are incident on the internal space, the light can be emitted from the same light transmission window. Therefore, in both the case of a long optical path and the case of a short optical path, since it is not necessary to greatly change the arrangement of the light emitting part and the light detecting part, the optical design of the multiple reflection cell can be simplified, and the size of the entire optical system and the number of components of the optical system can be reduced.

[0015] Specific examples of the pair of mirrors that multiply the reflection include spherical mirrors or toroidal mirrors.

[0016] Moreover, as an analyzer that irradiates light on a multiple reflection cell into which a sample gas is introduced, detects the light emitted from the multiple reflection cell, and analyzes the component to be measured contained in the sample gas, there is provided one including the multiple reflection cell, a light emitting part that emits light to the light transmission window, a light detecting part that detects the light emitted from the light transmission window, and a concentration calculation part that calculates the concentration of the component to be measured based on the output signals from these components. In addition, as an analysis method that irradiates light on a multiple reflection cell into which a sample is introduced, detects the light emitted from the multiple reflection cell, and analyzes the component to be measured contained in the sample, the cell includes one light transmission window that allows light to enter and exit from the internal space into which the sample is introduced, and a reflection mechanism provided in the internal space that reflects the light incident from the light transmission window a plurality of times by a plurality of planar mirrors and then emits the light to the light transmission window. The analysis method includes irradiating light on the light transmission window, detecting the light emitted from the light transmission window after being reflected by the reflection mechanism, and calculating the concentration of the component to be measured based on the detected light.

[0017] With such a configuration, the same operational effects as those of the above-described multiple reflection cell can be obtained.

[0018] In the analyzer, the reflection mechanism further includes a pair of mirrors provided to face each other in the internal space. One of the pair of mirrors has a light passage portion through which light from the light emitting portion enters and light is emitted to the light detecting portion, and the other mirror multiplies the light passing through the light passage portion between the one mirror and then emits the light to the light passage portion. The light emitting portion includes a light emitting portion for short optical path that emits light for short optical path to the plurality of plane mirrors, and a light emitting portion for long optical path that emits light for long optical path to the pair of mirrors. The light detecting portion includes a light detecting portion for short optical path that detects the light for short optical path emitted from the plurality of plane mirrors, and a light detecting portion for long optical path that detects the light for long optical path emitted from the pair of mirrors.

[0019] With such a configuration, in addition to forming a short optical path in the internal space by the plane mirror, the reflection mechanism multiplies the light between the pair of mirrors. Therefore, the analyzer can analyze a measurement target component that requires measurement with a long optical path length, such as when the measurement target component has a low concentration. As a result, since the analyzer can analyze both the measurement target component with a low concentration and the measurement target component with a high concentration, it can analyze the measurement target component in a wide concentration range. In addition, in both the case where the optical path length is short and the case where the optical path length is long, there is no need to change the structures of the light emitting portion and the light detecting portion, and it is only necessary to change the type of mirror that reflects the light according to the length of the optical path length. Therefore, the optical design of the entire optical system of the analyzer that irradiates the multiple reflection cell with light and detects the light of the multiple reflection cell can be simplified.

[0020] Specific examples of the measurement target component include water, ammonia, carbon monoxide, carbon dioxide, methane, ethane, ethylene, acetylene, or methanol.

Advantages of the Invention

[0021] According to the present invention configured as described above, it is possible to realize a short optical path with a reduced number of reflections of the laser light without significantly changing the design of the multi-reflection cell such as the optical system, the light transmission window, the cell length, and / or the cell volume.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0023] Hereinafter, an embodiment of an analyzer according to the present invention will be described with reference to the drawings. Note that, for the sake of clarity, any of the drawings shown below may be schematically drawn with appropriate omissions or exaggerations. The same reference numerals are given to the same components, and the description thereof will be omitted as appropriate.

[0024] <Configuration of the Analyzer> The analyzer 100 in the present embodiment analyzes a measurement target component contained in a sample gas such as combustion gas or process gas, such as gas during combustion or combustion exhaust gas.

[0025] Here, the gas during combustion refers to the gas during combustion in internal combustion engines such as automobiles, external combustion engines, industrial furnaces, incinerators, turbines, or power plants, etc. The combustion exhaust gas refers to the gas after combustion discharged from internal combustion engines such as automobiles, external combustion engines, industrial furnaces, incinerators, turbines, or power plants, etc. Further, the process gas refers to the gas in chemical plants such as petrochemical, coal chemical, natural gas chemical, petroleum refining, methanation, or gasification furnaces, etc. It includes, in addition to the raw material gas such as natural gas, the gas separated in the chemical plant, or the gas generated in the chemical plant, etc. Furthermore, the measurement target component is at least one of carbon dioxide (CO2), carbon monoxide (CO), ethylene (C2H4), ethane (C2H6), water (H2O), acetylene (C2H2), methane (CH4), ammonia (NH3), or methanol (CH3OH).

[0026] Specifically, as shown in FIG. 1, the analyzer 100 includes a multi-reflection cell 10 into which a sample gas is introduced, a light emitting unit 20 that irradiates light to the multi-reflection cell 10, a light detection unit 30 that detects the light emitted from the multi-reflection cell 10, an information processing device 40 that analyzes the measurement target component contained in the sample gas based on the light intensity signal detected by the light detection unit 30, and a display unit 50 such as a display that displays the analysis result analyzed by the information processing device 40. Note that the analyzer 100 may not include the display unit 50. Since the multi-reflection cell 10 is characteristic of the analyzer 100 according to the present invention, first, the other parts will be described.

[0027] The light emitting unit 20 is provided outside the multi-reflection cell 10. Specifically, the light emitting unit 20 is, for example, a semiconductor laser that emits laser light. In this embodiment, the laser light from the semiconductor laser is directly incident on the multi-reflection cell 10, but the laser light from the semiconductor laser may be introduced into the multi-reflection cell 10 via an optical element such as a mirror, for example.

[0028] The light detection unit 30 is provided outside the multiple reflection cell 10 on the same side as the light emission unit 20, and is provided at a position different from the optical path of the light emitted from the light emission unit 20 in order to avoid interference with the light emission unit 20. Here, a thermal type such as a relatively inexpensive thermopile is used, but other types such as quantum type photoelectric elements with good responsiveness such as HgCdTe, InGaAs, InAsSb, or PbSe may also be used. In this embodiment, the light emitted from the multiple reflection cell 10 is directly incident on the light detection unit 30, but the light emitted from the multiple reflection cell 10 may be incident on the light detection unit 30 via a detection optical element M such as a mirror.

[0029] The information processing device 40 includes an analog electric circuit composed of a buffer, an amplifier, etc., a digital electric circuit composed of a CPU, a memory, etc., and an AD converter, a DA converter, etc. that mediate between these analog / digital electric circuits. According to a predetermined program stored in a predetermined area of the memory, the CPU and its peripheral devices cooperate to receive the output signal from the light detection unit 30 and perform arithmetic processing on its value to calculate the concentration of the component to be measured, thereby at least exerting the function as a concentration calculation unit.

[0030] <Configuration of the multiple reflection cell> Next, the multiple reflection cell 10, which is a feature of the analyzer 100 according to the present invention, will be described in detail.

[0031] As shown in FIG. 2, the multiple reflection cell 10 includes a cell body 11 in which an internal space S into which the sample gas is introduced is formed, a light transmission window 12 through which the light from the light emission unit 20 passes, and a reflection mechanism 13 provided in the internal space S that reflects the light incident on the internal space S a plurality of times.

[0032] The cell body 11 forms a housing having a substantially rectangular parallelepiped shape, for example. The cell body 11 is provided with an introduction port P1 for introducing a sample gas into the internal space S and a derivation port P2 for deriving the sample gas from the internal space S. The sample gas is introduced into the internal space S through this introduction port P1. In the following, for convenience of explanation, the longitudinal direction of the cell body 11 is defined as the left-right direction.

[0033] The light transmission window 12 allows the light from the light emitting unit 20 to enter the internal space S and allows the light reflected by the reflection mechanism 13 to exit the internal space S. In the present embodiment, the angle at which the light enters the light transmission window 12 from the light emitting unit 20 is different from the angle at which the light exits from the light transmission window 12 to the outside of the internal space S. Further, in the present embodiment, one light transmission window 12 is provided on the side wall portion of the cell body 11. The light transmission window 12 is formed of a transparent material such as quartz, calcium fluoride, or barium fluoride that hardly absorbs light in the absorption wavelength band of the measurement target component contained in the sample gas.

[0034] The reflection mechanism 13 reflects the light incident on the internal space S from the light transmission window 12 a plurality of times by the reflecting surfaces of a plurality of plane mirrors and then emits it from the light transmission window 12. In the present embodiment, as shown in FIG. 3, the reflection mechanism 13 has an elongated shape with a small thickness, whereby the internal shape of the cell body 11 also becomes a flat shape with a small thickness. Here, the flat shape may be appropriately changed to a rectangular shape or an elliptical shape in a plan view. Further, the internal shape of the cell body 11 is not limited to the flat shape and may be other shapes.

[0035] In this embodiment, the reflection mechanism 13 includes a first planar mirror 131 and a second planar mirror 132 provided in the internal space S facing the light transmission window 12. The first planar mirror 131 has a reflecting surface that reflects the light incident from the light transmission window 12 toward the second planar mirror 132. The second planar mirror 132 has a reflecting surface that reflects the light reflected by the first planar mirror 131 toward the light transmission window 12. That is, the reflection mechanism 13 in this embodiment is configured to emit light from the light transmission window 12 after reflecting the light twice in the internal space S.

[0036] Further, in this embodiment, the reflection mechanism 13 is configured to cause the light to travel to and fro once in the internal space S using the first planar mirror 131 and the second planar mirror 132 and emit the light from the light transmission window 12. Here, the one round trip of the light in the internal space S means that when the optical path in which the light travels in the right direction is the forward path of the light and the optical path in which the light travels in the left direction is the return path of the light, the forward path and the return path of the light are each one when the light incident from the light transmission window 12 exits from the light transmission window 12.

[0037] The first planar mirror 131 and the second planar mirror 132 are provided symmetrically with respect to the central axis C which is the axis passing through the center of the light transmission window 12 in the internal space S. Specifically, the reflecting surface of the first planar mirror 131 and the reflecting surface of the second planar mirror 132 are provided facing each other via the central axis C of the light transmission window 12. Further, the reflecting surface of the first planar mirror 131 and the reflecting surface of the second planar mirror 132 are provided inclined with respect to the central axis C of the light transmission window 12 in a plan view so as to face the light transmission window 12. Thereby, the optical path from the first planar mirror 131 to the second planar mirror 132 becomes substantially parallel to the side surface of the cell body 11.

[0038] Furthermore, the reflection mechanism 13 may further include a connecting portion 133 that connects the first planar mirror 131 and the second planar mirror 132 in a state where the reflecting surfaces of the first planar mirror 131 and the second planar mirror 132 face each other. The connecting portion 133 is generally in the shape of a rectangular parallelepiped, and the side surface portion of the connecting portion 133 serves as a connecting surface 133a that connects the reflecting surface of the first planar mirror 131 and the reflecting surface of the second planar mirror 132. In the present embodiment, the connecting surface 133a is a flat surface so as not to obstruct the optical path from the first planar mirror 131 to the second planar mirror 132. However, the connecting surface 133a does not have to be a flat surface as long as it does not obstruct the optical path from the first planar mirror 131 to the second planar mirror 132.

[0039] <Effects of the present embodiment> In such a multiple reflection cell 10, after the reflection mechanism 13 reflects light a plurality of times by the reflecting surfaces of the plurality of planar mirrors 131 and 132, the light is emitted toward the light transmission window 12. Therefore, the light incident and emitted can be made through the same light transmission window 12. As a result, a short optical path can be realized without significantly changing the design of the multiple reflection cell 10, such as the optical system, the light transmission window 12, the cell length, and / or the cell volume. In addition, since the reflection mechanism 13 uses a plurality of planar mirrors when reflecting light a plurality of times, it is easier to adjust the direction in which the light is reflected compared to the case of using other shaped mirrors, and the optical design of the internal space S can be simplified.

[0040] Also, the first planar mirror 131 reflects the light incident from the light transmission window 12 toward the second planar mirror 132, and the second planar mirror 132 reflects the light reflected by the first planar mirror 131 toward the light transmission window 12. As a result, a short optical path for two reflections can be realized when the light incident and emitted are through the same light transmission window. In addition, since a short optical path for two reflections can be realized by using only the two planar mirrors 131 and 132, the optical design of the internal space S can be further simplified. Furthermore, the sensitivity when measuring a high-concentration measurement target component, which is a measurement target component for which it is preferable to analyze with a short optical path length, can be improved.

[0041] In addition, since the first planar mirror 131 and the second planar mirror 132 are connected by the connecting portion 133, the reflecting mechanism 13 has an integral structure. Therefore, the reflecting mechanism 13 can be easily installed in the internal space S as compared with the case where the first planar mirror 131 and the second planar mirror 132 are separate.

[0042] Moreover, since the first planar mirror 131 and the second planar mirror 132 are symmetrically provided with respect to the central axis C which is the axis passing through the center of the light transmission window 12 in the internal space S, the optical design of the internal space S can be further simplified and the multiple reflection cell 10 can be easily miniaturized.

[0043] <Other Embodiments> Note that the present invention is not limited to the above-described embodiments.

[0044] In the above-described embodiment, the reflecting mechanism 13 has two planar mirrors, i.e., the first planar mirror 131 and the second planar mirror 132. However, the number of planar mirrors included in the reflecting mechanism 13 is not limited to two, and it may have three or more planar mirrors. For example, as shown in FIG. 4, the reflecting mechanism 13 may have a third planar mirror 134 that reflects the light reflected by the first planar mirror 131 toward the second planar mirror 132.

[0045] In this case, the third planar mirror 134 is provided in the internal space S between the elongated members constituting the first planar mirror 131 and the second planar mirror 132 and the light transmission window 12. Further, the reflecting surface of the third planar mirror 134 is provided to face the reflecting surfaces of the first planar mirror 131 and the second planar mirror 132, and does not face the light transmission window 12. By using the third planar mirror 134 in addition to the first planar mirror 131 and the second planar mirror, the reflecting mechanism 13 is configured to cause the light to travel back and forth twice in the internal space S. Thereby, the optical path length in the internal space S can be made longer as compared with the configuration in which the light travels back and forth once in the internal space S.

[0046] In the above embodiment, the reflection mechanism 13 is configured such that the first plane mirror 131 and the second plane mirror 132 reflect light twice to form a short optical path in the internal space S. However, the reflection mechanism 13 may be configured to form a long optical path in the internal space S in addition to forming a short optical path in the internal space S. For example, as shown in FIG. 5, the reflection mechanism 13 may further include a pair of mirrors 135a and 135b provided opposite to each other in the internal space S, and may be configured to perform multiple reflections between the pair of mirrors 135a and 135b. In this case, a light emitting portion and a light detecting portion are provided corresponding to each of the short optical path and the long optical path. That is, a light emitting portion 20a for the short optical path and a light detecting portion 30a for the short optical path are provided, and a light emitting portion 20b for the long optical path and a light detecting portion 30b for the long optical path are provided. Note that the short optical path refers to an optical path having fewer reflection times in the internal space S than the long optical path. In the present embodiment, the short optical path is an optical path in which the number of reflections of the laser light in the internal space S is 10 or less.

[0047] Specifically, the pair of mirrors 135a and 135b includes one mirror 135a on which a light passing portion W through which light from the light emitting portion 20 is incident and which emits light to the light detecting portion 30 is formed, and the other mirror 135b which emits light to the light passing portion W after multiple-reflecting the light incident from the light passing portion W between the one mirror 135a. Here, the one mirror 135a is provided on the side wall portion side of the multiple reflection cell 10 provided with the light transmission window 12. Also, the other mirror 135b is obtained by changing the flat connection surface 133a in the above embodiment to an aspherical surface or a spherical surface. The reflection surfaces of the pair of mirrors 135a and 135b are provided opposite to each other.

[0048] In FIG. 5, the pair of mirrors 135a and 135b are aspherical mirrors such as toroidal mirrors with different radii of curvature for two mutually orthogonal axes, but they may also be spherical mirrors. Further, the multiple reflection cell may be a Herriott cell or a White cell. Additionally, in FIG. 5, the other mirror 135b is provided separately and detachably from the first plane mirror 131 and the second plane mirror 132, but the other mirror 135b may be integrally formed with the first plane mirror 131 and the second plane mirror 132. Also, the light passage portion W may be made of a transparent material such as quartz, calcium fluoride, or barium fluoride that has almost no light absorption in the absorption wavelength band of the component to be measured, or it may be a hole formed by penetrating through one of the mirrors 135a. Furthermore, in FIG. 5, the light passage portion W is provided separately from the light transmission window 12, but the light passage portion W and the light transmission window 12 may be common.

[0049] With such a configuration, in addition to forming a short optical path in the internal space S by the first plane mirror 131 and the second plane mirror 132, the reflection mechanism 13 causes light to be multiply reflected between the pair of mirrors 135a and 135b. In addition, corresponding to each of the short optical path and the long optical path, a light emission portion 20a for the short optical path and a light detection portion 30a for the short optical path are provided, and a light emission portion 20b for the long optical path and a light detection portion 30b for the long optical path are provided. As a result, by changing the mirror to be reflected, it is possible to both shorten and lengthen the optical path length of the internal space S, and it is possible to detect any light in the short optical path and the long optical path. Therefore, it is possible to analyze any measurement target component, whether it is a low-concentration measurement target component or a high-concentration measurement target component.

[0050] In addition, in both the case where the optical path length is short and the case where the optical path length is long, it is not necessary to change the arrangements of the light emitting unit 20a for short optical paths, the light detecting unit 30a for short optical paths, the light emitting unit 20b for long optical paths, and the light detecting unit 30b for long optical paths. When analyzing using a short optical path or a long optical path, the user only needs to change the type of mirror that reflects light according to the length of the optical path. Therefore, the optical design of the entire optical system of the analyzer 100 that irradiates the multi-reflection cell 10 with light and detects the light of the multi-reflection cell 10 can be simplified.

[0051] In the above embodiment, the sample introduced into the internal space S was the sample gas which is a gas, but it may be a sample liquid which is a liquid.

[0052] In the above embodiment, the reflection mechanism 13 was configured to include the connecting portion 133, but it may be configured not to include the connecting portion 133. In this case, the first planar mirror 131 and the second planar mirror 132 are respectively arranged separately in the internal space S.

[0053] In the above embodiment, the first planar mirror 131 and the second planar mirror 132 were provided symmetrically with respect to the central axis C of the light transmission window 12, but the locations where the first planar mirror 131 and the second planar mirror 132 are provided are not limited to this. As long as it is a location in the internal space S where at least the first planar mirror 131 reflects light toward the second planar mirror 132 and the second planar mirror 132 reflects the light toward the light transmission window 12, the first planar mirror 131 and the second planar mirror 132 may be provided anywhere in the internal space S.

[0054] In the above-described embodiment, the light-transmitting window 12 was provided singly on the side wall of the cell body 11. However, if it is not necessary to divide the optical path outside the multiple reflection cell 10 into a short optical path and a long optical path, a plurality of light-transmitting windows 12 may be provided. For example, as shown in FIG. 6, a partition wall W that divides the light-transmitting window 12 into two regions along the central axis C may be provided. In this case, the light-emitting unit 20 makes light incident on one region of the light-transmitting window 12, and the light is emitted from the other region of the light-transmitting window 12 to the light-detecting unit 30. Note that the partition wall W may divide the light-transmitting window 12 into three or more regions.

[0055] In addition, various modifications and combinations of the embodiments may be made as long as they do not depart from the spirit of the present invention.

Explanation of Reference Numerals

[0056] 100 ··· Analyzer 10 ··· Multiple reflection cell 11 ··· Cell body 12 ··· Light-transmitting window 13 ··· Reflection mechanism 131 ··· First planar mirror 132 ··· Second planar mirror 133 ··· Connecting portion 133a ··· Connecting surface 135 ··· Pair of mirrors 135a ··· One mirror 135b ··· The other mirror 20 ··· Light-emitting unit 30 ··· Light-detecting unit 40 ··· Information processing device S ··· Internal space C ··· Central axis

Claims

1. A multiple reflection cell in which a sample is introduced into an internal space and light is reflected in the internal space, one light transmission window for allowing light to enter and exit the internal space, and a reflection mechanism provided in the internal space for reflecting the light incident from the light transmission window a plurality of times by the reflecting surfaces of a plurality of planar mirrors and then allowing the light to exit from the light transmission window.

2. The reflection mechanism has a first planar mirror and a second planar mirror provided in the internal space facing the light transmission window, the first planar mirror reflects the light incident from the light transmission window toward the second planar mirror, and the second planar mirror reflects the light reflected by the first planar mirror toward the light transmission window. The multiple reflection cell according to claim 1.

3. The reflection mechanism further includes a connecting portion that connects the first planar mirror and the second planar mirror in a state where the reflecting surface of the first planar mirror and the reflecting surface of the second planar mirror face each other. The multiple reflection cell according to claim 2.

4. The first planar mirror and the second planar mirror are symmetrically provided with respect to a central axis that is an axis passing through the center of the light transmission window in the internal space. The multiple reflection cell according to claim 2 or 3.

5. The reflection mechanism further includes a pair of mirrors provided to face each other in the internal space, and the pair of mirrors includes one mirror on which the light transmission window is formed, and the other mirror that allows the light to exit from the light transmission window after multiple reflections of the light incident from the light transmission window between the one mirror. The multiple reflection cell according to any one of claims 1 or 4.

6. The pair of mirrors are spherical mirrors or toroidal mirrors. The multiple reflection cell according to claim 5.

7. An analyzer that irradiates light on a multi-reflection cell into which a sample gas is introduced, detects the light emitted from the multi-reflection cell, and analyzes a measurement target component contained in the sample gas, comprising: The multi-reflection cell according to any one of claims 1 to 6; A light emitting unit that emits light to the light transmission window; A light detection unit that detects the light emitted from the light transmission window; A concentration calculation unit that calculates the concentration of the measurement target component based on an output signal from the light detection unit.

8. The reflection mechanism further includes a pair of mirrors provided to face each other in the internal space, The pair of mirrors, One mirror in which a light passage portion is formed for allowing light from the light emitting unit to enter and for emitting light to the light detection unit; And the other mirror that multiplies and reflects the light that has passed through the light passage portion between the one mirror and then emits the light to the light passage portion. The light emitting unit, A short optical path light emitting unit that emits short optical path light to the plurality of plane mirrors; And a long optical path light emitting unit that emits long optical path light to the pair of mirrors. The light detection unit, A short optical path light detection unit that detects short optical path light emitted from the plurality of plane mirrors; And a long optical path light detection unit that detects long optical path light emitted from the pair of mirrors. The analyzer according to claim 7.

9. The measurement target component is water, ammonia, carbon monoxide, carbon dioxide, methane, ethane, ethylene, acetylene, or methanol. The analyzer according to claim 7 or 8.

10. A method for analyzing a component to be measured contained in a sample, comprising irradiating a multi-reflection cell into which the sample has been introduced with light, detecting the light emitted from the multi-reflection cell, and analyzing the component to be measured contained in the sample, wherein the multi-reflection cell includes, a light transmission window for allowing light to enter and exit an internal space into which the sample is introduced, and a reflection mechanism provided in the internal space for reflecting light incident from the light transmission window a plurality of times by reflection surfaces of a plurality of planar mirrors and then emitting the light to the light transmission window, and the analysis method includes, causing light to enter the light transmission window, detecting the light emitted from the light transmission window after being reflected by the reflection mechanism, and calculating the concentration of the component to be measured based on the detected light.

Images