JP6283291B2 - Gas analyzer and gas cell - Google Patents

Description

  Embodiments described herein relate generally to a gas analyzer and a gas cell.

  Gas analyzers using gas cells are used for various purposes such as breath diagnosis, environmental measurement, and exhaust analysis. A highly accurate analysis is required.

JP 2010-243269 A

  Embodiments of the present invention provide a highly accurate gas analyzer and gas cell.

According to the embodiment of the present invention, the gas analyzer includes a gas cell, a light source unit, a detection unit, a first reflection unit, and a second reflection unit. The gas cell includes a space into which a sample gas is introduced. The light source unit makes measurement light incident on the sample gas introduced into the space. The detection unit detects the measurement light emitted from the space. The surface of the first reflecting portion that faces the second reflecting portion and the surface of the second reflecting portion that faces the first reflecting portion are in a direction from the first reflecting portion toward the second reflecting portion. Concave and continuous around the axis. The space is disposed between the first reflecting portion and the second reflecting portion. The first optical path length of the measurement light until it enters the space in the first state and exits from the space is the length of the measurement light that enters the space and exits from the space in the second state. Different from the second optical path length. The wavelength of the measurement light in the first state is different from the wavelength of the measurement light in the second state.
According to another embodiment of the present invention, the gas cell includes a container including a space into which the sample gas is introduced, a first reflective portion including a light reflective first reflective region and a light transmissive first transparent region. And a second reflection part including a light reflective second reflective region and a light transmissive second transparent region. The surface of the first reflecting portion that faces the second reflecting portion and the surface of the second reflecting portion that faces the first reflecting portion are in a direction from the first reflecting portion toward the second reflecting portion. Concave and continuous around the axis. The space is disposed between the first reflecting portion and the second reflecting portion. Measurement light enters the space from the first transmission region, is reflected by the first reflection region and the second reflection region, and exits from the second transmission region. The relative position of the second transmission region in the first state with respect to the first transmission region is different from the relative position of the second transmission region in the second state with respect to the first transmission region. The first optical path length of the measurement light from entering the first transmission region in the first state to exiting from the second transmission region is incident on the first transmission region in the second state and 2 is different from the second optical path length of the measurement light until it is emitted from the transmission region.

FIG. 1A and FIG. 1B are schematic views illustrating the gas analyzer according to the first embodiment. FIG. 2A and FIG. 2B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment. FIG. 3A and FIG. 3B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment. FIG. 4A and FIG. 4B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment. It is a schematic diagram which illustrates another gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates another gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates another gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates another gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates another gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates the gas analyzer which concerns on 2nd Embodiment. It is a schematic diagram which illustrates the gas analyzer which concerns on 3rd Embodiment. FIG. 12A and FIG. 12B are schematic views illustrating characteristics of the gas analyzer according to the embodiment. It is a mimetic diagram which illustrates a part of gas analyzer concerning an embodiment. It is a mimetic diagram which illustrates a part of gas analyzer concerning an embodiment. FIG. 15A and FIG. 15B are schematic views illustrating a part of the gas analyzer according to the embodiment. FIG. 16A to FIG. 16C are schematic views illustrating a part of the gas analyzer according to the embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
It should be noted that the disclosure is merely an example, and those skilled in the art can easily correspond to appropriate changes while maintaining the gist of the invention, and are naturally included in the scope of the present invention. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited.
In addition, in the present specification and each drawing, elements similar to those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description may be omitted as appropriate.

(First embodiment)
FIG. 1A and FIG. 1B are schematic views illustrating the gas analyzer according to the first embodiment.
As shown in FIG. 1A, the gas analyzer 110 according to the present embodiment includes a gas cell 20, a light source unit 30, a detection unit 40, a calculation unit 45, and a rotation drive unit 53.

  A sample gas 50 is introduced into the gas cell 20. The gas cell 20 includes a container 23. A space 23 s is formed by the container 23. The sample gas 50 is introduced into the space 23s. The gas cell 20 is further provided with a first reflecting portion 21 and a second reflecting portion 22. A space 23 s into which the sample gas 50 is introduced is disposed between the first reflecting portion 21 and the second reflecting portion 22. In this example, the first reflecting portion 21 and the second reflecting portion 22 are disposed in the container 23. In the embodiment, the first reflecting part 21 and the second reflecting part 22 may be disposed outside the container 23. At least a part of the space 23 s is disposed between the first reflecting part 21 and the second reflecting part 22. The surface of the first reflecting portion 21 that faces the second reflecting portion 22 and the surface of the second reflecting portion 22 that faces the first reflecting portion 21 are concave. Each of these surfaces is, for example, a spherical surface or an aspherical surface. The first reflecting portion 21 and the second reflecting portion 22 may be included in the gas cell 20 or may be separate from the gas cell 20.

  The light source unit 30 causes light (measurement light 30L) to enter the space 23s. In this example, the light source unit 30 includes a light emitting unit 30a and a driving unit 30b. The drive unit 30b is electrically connected to the light emitting unit 30a. The drive unit 30b supplies power for light emission to the light emitting unit 30a. As will be described later, for example, an external resonator (EC) type quantum cascade laser (QCL) is used as the light emitting unit 30a. An example of the light emitting unit 30a will be described later.

  The measurement light 30L passes through the space 23s in a state where the sample gas 50 is introduced into the space 23s. A part of the measurement light 30 </ b> L is absorbed by the substance contained in the sample gas 50. Of the measurement light 30L, a component having a wavelength specific to the substance contained in the sample gas 50 is absorbed. The degree of absorption depends on the concentration of the substance and the optical path length. Examples of substances will be described later.

  The detection unit 40 detects the measurement light 30L that has passed through the space 23s in a state where the sample gas 50 is introduced into the space 23s. The detection unit 40 detects the intensity of the light (measurement light 30L) that has passed through the space 23s. For the detection unit 40, for example, an element having sensitivity in the infrared region is used. For the detection unit 40, for example, a thermopile or a semiconductor sensor element (for example, MCT (HgCdTe)) is used.

  The detection unit 40 measures the intensity of light transmitted through the sample gas 50. In this example, the measured light intensity is input to the calculation unit 45 as a signal. Based on this signal, the calculation unit 45 calculates the partial pressure of the substance contained in the sample gas 50. The amount (concentration) of the substance is determined based on the partial pressure of the substance. An example of a method for calculating the concentration of the substance contained in the sample gas 50 will be described later.

  As described above, the degree of absorption of a substance depends on the concentration of the substance and the optical path length. Depending on the concentration of the substance and the absorption rate (absorbance) of the substance, if the optical path length is short, the result of the substance concentration may be inaccurate. In the embodiment, the first reflecting unit 21 and the second reflecting unit 22 are used to reflect the measurement light 30L to increase the optical path length.

  The gas cell 20 is, for example, a multipass cell. The first reflection unit 21 includes a first reflection region 21a and a first transmission region 21b. The second reflection part 22 includes a second reflection region 22a and a second transmission region 22b. The first reflection region 21a and the second reflection region 22a are reflective to the measurement light 30L. The first transmission region 21b and the second transmission region 22b are transmissive to the measurement light 30L. These transmissive areas are, for example, areas of holes provided in the reflecting portion.

  In the gas cell 20, the measurement light 30L is incident from the first transmission region 21b. The incident measurement light 30L is reflected by the second reflection region 22a and reflected by the first reflection region 21a. The incident measurement light 30L repeatedly reciprocates between the first reflecting portion 21 and the second reflecting portion 22 (space 23s) and is emitted from the second transmitting region 22b. The number of passes (the number of passes) of the incident measurement light 30L through the space 23s is determined by the relative position between the first transmission region 21b and the second transmission region 22b.

  The optical path length of the incident measurement light 30L is calculated by “the distance between the first reflection unit 21 and the second reflection unit 22” × the number of passes. For example, when the distance between the first reflecting unit 21 and the second reflecting unit 22 is 37 cm and the number of passes is 25, the optical path length is 925 cm (= 37 cm × 25).

  It is preferable that the optical path length is set so that appropriate detection sensitivity can be obtained according to the type of substance. For example, if the optical path length is excessively short, the absorption is small and the calculation of the concentration of the substance becomes difficult. If the optical path length is excessively long, it is excessively absorbed and it becomes difficult to calculate the concentration of the substance. For this reason, in a reference example in which the concentration of a plurality of substances is detected using a gas cell having a constant optical path length, the optical path length may not be suitable for the substance depending on the type of the substance. In this reference example, it may be difficult to calculate the concentrations of a plurality of substances.

  In the embodiment, an appropriate optical path length is used in accordance with each of a plurality of target substances. A plurality of optical path lengths are formed in one gas cell. The degree of absorption of measurement light can be made appropriate for each of a plurality of substances. Thereby, it is possible to obtain the concentration with high accuracy for each of the plurality of substances.

  As shown in FIG. 1B, the gas analyzer 110 is provided with a rotation drive unit 53. The rotation drive unit 53 rotates the second reflection unit 22 with the direction from the first reflection unit 21 toward the second reflection unit 22 as an axis (rotation axis 53a), whereby the second transmission region 22b moves. The relative position of the first transmission region 21b and the second transmission region 22b changes. That is, the position of the second transmission region 22b in the first state ST1 is different from the position of the second transmission region 22b in the second state ST2. As a result, the number of paths, that is, the optical path length changes.

  In the first state ST1 and the second state ST2, for example, the sample gas 50 contains different substances, and the absorption coefficients of the plurality of substances are different from each other. For example, in the first state ST1, the sample gas 50 contains the first substance, and in the second state ST2, the sample gas 50 contains the second substance. The absorption coefficient of the first substance is different from the absorption coefficient of the second substance.

  In the first state ST1 and the second state ST2, for example, the concentrations of substances contained in the sample gas 50 are different from each other. For example, the concentration of the first substance in the sample gas 50 in the first state ST1 is the first concentration. The concentration of the first substance in the sample gas 50 in the second state ST2 is the second concentration. The first concentration is different from the second concentration.

  In this example, a rotation angle sensor 54 is further provided. The rotation angle θ of the second reflection unit 22 is measured by the rotation angle sensor 54. A signal related to the measured rotation angle θ is input to the calculation unit 45. In the calculation unit 45, the number of passes is calculated based on the rotation angle θ.

  Thus, in the embodiment, a derivation unit (in this example, the rotation angle sensor 54) that derives a value (for example, the rotation angle θ) according to the difference between the first optical path length and the second optical path length is provided. The concentration of the substance may be calculated based on a value (for example, a rotation angle θ) corresponding to the difference in optical path length derived by the deriving unit.

  That is, in the calculation unit 45, for example, based on the detection result of the measurement light 30L detected by the detection unit 40 and the above value estimated by the derivation unit (in this example, the rotation angle sensor 54), The concentration of the substance contained in the sample gas 50 is calculated.

  In the embodiment, a rotation control unit 54 a that controls the operation of the rotation driving unit 53 may be provided. The rotation control unit 54 a monitors the rotation angle of the second reflecting unit 22 and controls the operation of the rotation driving unit 53. Thereby, the rotation angle θ of the second reflecting portion 22 is controlled. The rotation control unit 54a may include a rotation angle sensor 54.

  In this example, the rotation drive unit 53 also rotates the detection unit 40 around the rotation shaft 53a. That is, the rotation driving unit 53 rotates the detection unit 40 in conjunction with the rotation of the second reflection unit 22. The detection unit 40 rotates together with the second reflection unit 22. Thereby, when the 2nd reflection part 22 rotates and the 2nd transmission region 22b moves, the detection part 40 is located on the optical path of the measurement light 30L emitted from the 2nd transmission region 22b.

  Thus, in the gas analyzer 110, the gas cell 20 including the container 23 including the space 23s into which the sample gas 50 is introduced, and the light source unit 30 that makes the measurement light 30L incident on the sample gas 50 introduced into the space 23s. And a detection unit 40 for detecting the measurement light 30L emitted from the gas cell 20. The measurement light 30L enters the space 23s from the first transmission region 21b, is reflected by the first reflection region 21a and the second reflection region 22a, and exits from the second transmission region 22b.

  The relative position of the second transmission region 22b with respect to the first transmission region 21b in the first state ST1 is different from the relative position of the second transmission region 22b with respect to the first transmission region 21b in the second state ST2. In the first state ST1, the first optical path length of the measurement light 30L from entering the first transmissive region 21b to being emitted from the second transmissive region 22b is incident on the first transmissive region 21b in the second state ST2. This is different from the second optical path length of the measurement light L until it is emitted from the transmission region 22b. By changing the optical path length, highly accurate gas analysis can be performed for a plurality of substances.

FIG. 2A and FIG. 2B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment.
These drawings illustrate the case where a plurality of substances (for example, the first substance G1 and the second substance G2) are included in the sample gas 50. These figures correspond to the first state ST1.

  FIG. 2A is a schematic view illustrating the relationship between the relative position of the first transmission region 21b and the second transmission region 22b and the number of passes. FIG. 2B is a graph illustrating the relationship between transmittance and wavelength. The vertical axis in FIG. 2B is the transmittance Tr. The horizontal axis is the wavelength λ.

  As shown in FIG. 2A, in this example, the position of the first transmission region 21b is a predetermined position P0. The position of the second transmission region 22b is the first position P1. The measurement light 30L enters from the first transmission region 21b. The number of passes when the incident measurement light 30L is emitted from the second transmission region 22b is 25.

  As shown in FIG.2 (b), the transmittance | permeability of the light of the wavelength of the range of 1st wavelength range (lambda) R1 is reduced moderately by the 1st substance G1. The partial pressure PP1 (concentration) of the first substance G1 is calculated with high accuracy. The optical path length at this time is appropriate in detecting the concentration of the first substance G1. On the other hand, in the second substance G2, light having a wavelength in the second wavelength range λR2 is excessively absorbed. For this reason, the accuracy of calculation of the partial pressure PP2 is low.

FIG. 3A and FIG. 3B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment.
These figures correspond to the second state ST2.

  FIG. 3A is a schematic view illustrating the relationship between the relative position of the first transmission region 21b and the second transmission region 22b and the number of passes. FIG. 3B is a graph illustrating the relationship between transmittance and wavelength.

  As shown in FIG. 3A, in this example, the position of the first transmission region 21b is a predetermined position P0. The position of the second transmission region 22b is the second position P2. The measurement light 30L enters from the first transmission region 21b. The number of passes when the incident measurement light 30L exits from the second transmission region 22b is 11.

  As shown in FIG. 3B, the transmittance of light having a wavelength in the second wavelength range λR2 is moderately decreased by the second material G2. For example, the partial pressure PP2 of the second substance G2 is calculated with high accuracy. The optical path length at this time is appropriate in detecting the concentration of the second substance G2. On the other hand, the degree of absorption of the first substance G1 is excessively low, and the calculation accuracy of the partial pressure PP1 is low.

  The absorption rate of the first substance G1 is significantly different from the absorption rate of the second substance G2. For this reason, there is a reference example in which a cell for detecting the first substance G1 and a cell for detecting the second substance G2 are separately provided. In this reference example, since detection is performed using different cells, the stability of detection cannot be sufficiently high, and the accuracy is low. Furthermore, the size of the gas analyzer is increased. As the size increases, the cost increases.

  In contrast, in the embodiment, the absorption of both the first substance G1 and the second substance G2 is detected in one space 23s (one container 23). Thereby, stable detection can be performed and the accuracy is high. Then, by changing the optical path length to obtain appropriate absorption suitable for each of a plurality of substances, the accuracy of analysis is high.

FIG. 4A and FIG. 4B are schematic views illustrating characteristics of the gas analyzer according to the first embodiment.
These figures are graphs illustrating characteristics relating to gas analysis. The vertical axis | shaft of Fig.4 (a) and FIG.4 (b) is the transmittance | permeability Tr. The horizontal axis is the wavelength λ (nm).

In this example, CH ₄ and NH ₃ exist in the gas cell 20. The concentration of CH ₄ is 150 ppm. The concentration of NH ₃ is 10 ppm. In the example shown in FIG. 4A, the optical path length is 36 m, and in the example shown in FIG. 4B, the optical path length is 5.34 m. For example, CH ₄ absorbs light having a wavelength in the third wavelength range λR3 in the measurement light 30L.

As shown in FIG. 4 (a), the intensity of the wavelength range of the fourth wavelength range λR4 decreases by NH _3, NH ₃ partial pressure can be calculated with high accuracy. As shown in FIG. 4 (b), the intensity of the wavelength range of the third wavelength range λR3 decreases by CH _4, the partial pressure of CH ₄ can be calculated with high accuracy.

FIG. 5 is a schematic view illustrating another gas analyzer according to the first embodiment.
As shown in FIG. 5, in the gas analyzer 111, a wedge substrate 55 is provided in addition to the light source unit 30, the gas cell 20, the rotation drive unit 53, and the detection unit 40. The wedge substrate 55 is provided between the second transmission region 22b and the detection unit 40. The wedge substrate has a wedge-shaped cross section. The wedge substrate 55 rotates around the direction from the first reflecting portion 21 toward the second reflecting portion 22. In this example, the wedge substrate 55 includes a first substrate 55a and a second substrate 55b. The cross section of these substrates is wedge-shaped. That is, the thickness changes. These substrates rotate.

  The measurement light 30L emitted from the second transmission region 22b is incident on the first substrate 55a and the second substrate 55b. The measurement light 30L is refracted to change the traveling direction. The measurement light 30L is incident on the detection unit 40. The measurement light 30L can be incident on the detection unit 40 even when the position of the second transmission region 22b is rotated and changed by the rotation of the first substrate 55a and the second substrate 55b. The detection unit 40 may be fixed, or the movement distance of the detection unit 40 may be small. Since the number of moving parts can be reduced, the detection stability can be increased.

FIG. 6 is a schematic view illustrating another gas analyzer according to the first embodiment.
As shown in FIG. 6, the gas analyzer 112 is provided with a light receiving side galvanometer mirror unit 56 in addition to the light source unit 30, the gas cell 20, the rotation driving unit 53, and the detection unit 40. The light-receiving-side galvanometer mirror unit 56 is provided on the optical path between the second transmission region 22b and the detection unit 40.

  In this example, the light-receiving side galvanometer mirror part 56 includes a mirror part 56a and a mirror part 56b. The measurement light 30L emitted from the second transmission region 22b is reflected by the mirror part 56a and the mirror part 56b to change the traveling direction. By changing the traveling direction, the measurement light 30 </ b> L can enter the detection unit 40. Since the number of movable parts can be reduced, the detection stability can be increased.

FIG. 7 is a schematic view illustrating another gas analyzer according to the first embodiment.
As shown in FIG. 7, the gas analyzer 113 is provided with a lens 57 in addition to the light source unit 30, the gas cell 20, the rotation drive unit 53, and the detection unit 40. The lens 57 is provided between the second transmission region 22b and the detection unit 40. The measurement light 30L emitted from the second transmission region 22b is refracted to change the traveling direction and is incident on the detection unit 40. The diameter of the lens 57 is, for example, equal to or larger than the size of the second reflecting unit 22. Even when the position of the second transmission region 22b changes due to rotation, the measurement light 30L enters the detection unit 40.

FIG. 8 is a schematic view illustrating another gas analyzer according to the first embodiment.
As shown in FIG. 8, the gas analyzer 114 is provided with a light source unit 30, a gas cell 20, a rotation drive unit 53, and a detection unit 40. The detection unit 40 has a light receiving surface 40a. The area of the light receiving surface 40a is equal to or larger than the area of the movable region accompanying the rotation of the second transmission region 22b. For example, the area of the light receiving surface 40a is equal to or larger than the area of a circle having the radius of rotation of the second transmission region 22b. The area of the light receiving surface 40a is, for example, equal to or larger than the area of the second reflecting portion 22. Thereby, even when the position of the second transmission region 22b is changed by rotation, the measurement light 30L can be incident on the light receiving surface 40a.

FIG. 9 is a schematic view illustrating another gas analyzer according to the first embodiment.
As shown in FIG. 9, the gas analyzer 115 includes a light source unit 30, a gas cell 20, a rotation drive unit 53, and a detection unit 40. The detection unit 40 includes a plurality of detectors (such as a first detector 42a and a second detector 42b). The first detector 42a corresponds to the first position P1, for example. The second detector 42b corresponds to, for example, the second position P2. For example, the first detector 42a detects the intensity of the measurement light 30L emitted from the second transmission region 22b in the first state ST1. The second detector 42b detects the intensity of the measurement light 30L emitted from the second transmission region 22b in the second state ST2.

  According to the embodiment, for example, the number of passes is changed by rotationally moving the second transmission region 22b of the second reflection unit 22. That is, the optical path length is changed. In the present embodiment, the first reflection unit 21 may be rotated without rotating the second reflection unit 22. In conjunction with this, the light source unit 30 is rotated. That is, in the present embodiment, at least one of the first reflecting portion 21 and the second reflecting portion 22 rotates around the direction from the first reflecting portion 21 toward the second reflecting portion 22. Thereby, the optical path length is changed.

(Second Embodiment)
FIG. 10 is a schematic view illustrating a gas analyzer according to the second embodiment.
As shown in FIG. 10, the gas analyzer 120 includes a light source unit 30, a gas cell 20, a light source side galvano mirror unit 58, and a light receiving side galvano mirror unit 56. The light source side galvanometer mirror part 58 includes a mirror part 58a and a mirror part 58b. The light-receiving side galvanometer mirror part 56 includes a mirror part 56a and a mirror part 56b.

  The light source side galvanometer mirror unit 58 changes the direction of the measurement light 30L emitted from the light source unit 30 to enter the first reflection unit 21, and changes the incident angle of the measurement light 30L incident on the space 23s. The light source side galvanometer mirror unit 58 controls the direction of the measurement light 30L so as to enter the gas cell 20 from the first transmission region 21b.

  The inclination of the mirror part 58a and the mirror part 58b can be changed. The inclination angle of the light source side galvanometer mirror 58 changes, and the direction (angle) of the measurement light 30L changes.

  The measurement light 30 </ b> L emitted from the light source unit 30 enters the gas cell 20 (space 23 s) via the light source side galvanometer mirror unit 58. The incident angle of the measurement light 30L incident on the first transmission region 21b is changed. For example, the first incident angle of the measurement light 30L incident on the space 23s in the first state is different from the second incident angle of the measurement light L30 incident on the space 23s in the second state. By changing the incident angle, the number of passes changes. As a result, the optical path length changes. That is, for example, in the first state, the distance (first optical path length) from entering the first transmission region 21b at the first incident angle to exiting from the second transmission region 22b is equal to the second incidence in the second state. This is different from the distance (second optical path length) required to enter the first transmission region 21b at the corner and exit from the second transmission region 22b.

  On the other hand, the inclination of the mirror part 56a and the mirror part 56b of the light-receiving side galvanometer mirror part 56 can be changed. The inclination angle of the light-receiving-side galvanometer mirror unit 56 changes, and the measurement light 30L emitted from the second transmission region 22b enters the detection unit 40 via the light-receiving-side galvanomirror unit 56.

  In the present embodiment, the number of passes is changed by changing the inclination of the light source side galvanometer mirror unit 58. That is, the optical path length is changed. Thereby, an appropriate optical path length can be applied to various substances. According to the embodiment, highly accurate detection can be performed on various substances.

  In the gas analyzer according to the embodiment, a pass number monitor 68 for imaging the first reflection unit 21 or the second reflection unit 22 may be provided. You can check the number of passes.

(Third embodiment)
FIG. 11 is a schematic view illustrating a gas analyzer according to the third embodiment.
As shown in FIG. 11, the gas analyzer 121 includes a light source unit 30, a gas cell 20, a light source side galvano mirror unit 58, and a light receiving side galvano mirror unit 56.

  The measurement light 30L emitted from the light source unit 30 enters the gas cell 20 (space 23s) from the first transmission region 21b via the light source side galvanometer mirror unit 58. The measurement light 30L incident from the first transmission region 21b repeatedly reciprocates between the first reflection unit 21 and the second reflection unit 22 (space 23s) and is emitted from the first transmission region 21b. The measurement light 30 </ b> L emitted from the first transmission region 21 b is incident on the detection unit 40 via the light receiving side galvanomirror unit 56.

  By changing the inclination angle of the light source side galvanometer mirror 58, the direction (angle) of the measurement light 30L changes. As a result, the optical path length changes. That is, the first reflection unit 21 includes a light-reflective reflective region (first reflective region 21a) and a light-transmissive transmissive region (first transmissive region 21b). In this example, the first optical path length is a distance from the incident to the transmission region at the first incident angle, the reflection from the second reflecting portion 22 and the emission from the transmission region. The second optical path length is a distance from the light incident on the transmissive region at the second incident angle, reflected by the second reflecting portion 22 and emitted from the transmissive region. The first optical path length is different from the second optical path length.

  In the embodiment, an appropriate optical path length can be applied to various substances, and highly accurate detection can be performed on various substances.

A plurality of transmissive regions may be provided in the first reflecting portion 21. By changing the tilt angle of the light source side galvanometer mirror 58, the transmission region from which the measurement light 30L is emitted varies depending on the tilt angle. Thereby, the optical path length can be changed.
That is, the first reflection unit 21 includes a light-reflective reflective region (first reflective region 21a) and a plurality of light-transmissive regions. The first optical path length is a distance from one of the plurality of transmission regions that is incident on the first incident angle, reflected from the first reflection unit 21 and the second reflection unit 22, and emitted from one of the plurality of transmission regions. It is. The second optical path length is from the incident angle to one of the plurality of transmission regions at the second incident angle, the reflection from the first reflection unit and the second reflection unit 22, and the emission from another one of the plurality of transmission regions. Distance. The first optical path length is different from the second optical path length. Thus, a plurality of optical path lengths are provided. Accordingly, an appropriate optical path length can be applied to various substances, and highly accurate detection can be performed on various substances.

FIG. 12A and FIG. 12B are schematic views illustrating characteristics of the gas analyzer according to the embodiment.
These drawings illustrate an image of the first reflecting unit 21 captured by the pass number monitor 68. In FIG. 12A, the number of paths is 182. In FIG. 12B, the number of passes is 28. In this way, the number of passes (number of reflections) can be known by imaging.

In the embodiment, an example of a substance to be measured will be described.
The gas analyzer is used for diagnosis of exhalation, for example. The substance is, for example, a carbon dioxide isotope. In this case, for example, information on H. pylori is obtained. The substance is, for example, methane. In this case, for example, information on intestinal anaerobic bacteria is obtained. The substance is, for example, ethanol. In this case, for example, information about drinking is obtained. The substance is, for example, acetaldehyde. In this case, for example, information on alcohol consumption metabolites and lung cancer can be obtained. The substance is, for example, acetone. In this case, for example, information on diabetes is obtained. The substance is, for example, nitric oxide. In this case, for example, information about asthma is obtained. The substance is, for example, ammonia. In this case, for example, information on hepatitis is obtained. The substance is, for example, nonanal. In this case, for example, information on lung cancer is obtained. In the embodiment, the substance to be measured included in exhaled breath is arbitrary. The gas analyzer may be used, for example, for industrial gas analysis. For example, it can be used for monitoring an exhaust gas processing system of a processing apparatus such as a semiconductor factory. For example, in the case of an exhaust gas for etching, the substance is, for example, fluoride. The fluoride, for _{example, CF 4, C 2 F 6} , C 3 F 8, c-C 4 F 8, CHF 3, NF 3, SF 6 , and the like.

In the embodiment, an example of a method for calculating a partial pressure of a substance will be described.
In this example, the gas analyzer is used as an expiration diagnosis device.
In the gas analyzer, for example, a first operation is performed in a state where exhaled air is introduced into the space 23s. And the 2nd 2nd operation in the state which does not introduce exhalation into space 23s (air is introduced) is performed. The first operation is, for example, a detection operation for detecting the concentration of a target substance contained in exhaled air (sample gas 50). The second operation is, for example, a calibration operation (preparation operation) for obtaining a reference signal.

  A difference ΔVs between the signal Vs in the first operation and the signal Vs in the second operation is used as a value of the detection result of the detection unit 40.

  For example, a ratio is used as the difference ΔVs. For example, the signal Vs obtained in the first operation is the first signal Vs1. The signal Vs obtained in the second operation is set as a reference signal Vs0. For example, the ratio of the first signal Vs1 to the reference signal Vs0 (that is, Vs1 / Vs0) corresponds to the degree of absorption of the measurement light 30L in the space 23s. The degree of absorption is the ratio of the light intensity (I1) in the first operation to the light intensity (I0) in the second operation. At this time, I1 / I0 = e (−αLP). “E” is the base of the natural logarithm. “Α” is a constant (absorption coefficient). “L” is the optical path length of the measurement light 30L passing through the space 23s. “P” is the partial pressure of the target substance. The degree of absorption is obtained from the detected signal Vs. From this result, the partial pressure P of the target substance is known. The concentration is obtained from the partial pressure P.

  For the light source unit 30, for example, an external resonator type tunable quantum cascade laser is used. A plurality of distributed feedback (DFB) quantum cascade lasers that are coaxially coupled to each other may be used for the light source unit 30.

  Furthermore, when a distributed feedback type (DFB type) quantum cascade laser is used for the light source unit 30, the light source unit 30 modulates the wavelength of the measurement light 30L with a control signal. Then, the signal detected by the detection unit 40 may be frequency-detected corresponding to this control signal. In this case, a band pass filter may be provided between the second transmission region 22b and the detection unit 40. Thereby, light of a desired wavelength can be selectively observed.

Hereinafter, an example of the light emitting unit 30a of the light source unit 30 will be described.
FIG. 13 is a schematic view illustrating a part of the gas analyzer according to the embodiment.
As illustrated in FIG. 13, the light source unit 30 (light emitting unit 30a) includes a semiconductor light emitting element 30aL and a wavelength control unit 30aC. As will be described later, the semiconductor light emitting element 30aL emits emitted light by energy relaxation of electrons in subbands of a plurality of quantum wells, for example. For example, the wavelength control unit 30aC adjusts the wavelength of the emitted light to generate the first light L1 and the second light L2.

  For example, the wavelength control unit 30aC includes a first adjustment mechanism. The first adjustment mechanism shifts the wavelength of the infrared laser light emitted from the semiconductor light emitting element 30aL into the absorption spectrum of one kind of gases among a plurality of gases included in exhaled breath. The wavelength control unit 30aC may further include a second adjustment mechanism. For example, the second adjustment mechanism adjusts the wavelength by shifting the wavelength in the absorption spectrum of one kind of gas.

  For example, the first adjustment mechanism includes a diffraction grating 71. The diffraction grating 71 is provided so as to intersect with the optical axis 31Lx of the semiconductor light emitting element 30aL. The diffraction grating 71 forms an external resonator. The incident angle of the infrared laser light to the diffraction grating 71 is changed according to the absorption spectra of the plurality of substances contained in the sample gas 50. The incident angle is changed to, for example, angles β1 to β4. Thereby, the wavelength of infrared laser light is changed.

  For example, a stepping motor 99 and a drive control unit 98 are provided. The drive control unit 98 controls (drives) the stepping motor 99. The diffraction grating 71 is rotationally controlled by the stepping motor 99 and the drive control unit 98 around an axis that intersects the optical axis 31Lx.

  It is preferable to provide an antireflection coating film AR on the end face of the semiconductor light emitting element 30aL on the diffraction grating 71 side. A partially reflective coating film PR (Perfect Reflection) may be provided. The semiconductor light emitting element 30aL is disposed between the partial reflection coating film PR and the antireflection coating film AR. An external resonator is formed between the partially reflective coating film PR and the diffraction grating 71.

  In the embodiment, the wavelength may be further accurately adjusted by the second adjustment mechanism. For example, the drive part 30b (refer FIG. 1) can be used as a 2nd adjustment mechanism. The drive unit 30b changes at least one of the operating current value and the duty of the semiconductor light emitting element 30aL. The temperature control unit 90 may be used as the second adjustment mechanism. The temperature control unit 90 changes the temperature of the semiconductor light emitting element 30aL. For example, a Peltier element or the like is used as the temperature control unit 90. For example, a stress generating element may be used as the second adjustment mechanism. The stress generating element changes the external resonator length. As the stress generating element, for example, a piezo element or the like can be used.

FIG. 14 is a schematic view illustrating a part of the gas analyzer according to the embodiment.
FIG. 14 shows another example of the light emitting unit 30a.
In this example, a diffraction grating 71a is used as the first adjustment mechanism. The diffraction grating 71a moves in an XY plane that intersects the optical axis 31Lx of the semiconductor light emitting element 30aL at a predetermined incident angle γ. The diffraction grating 71 a is moved by, for example, the stepping motor 99 and the drive control unit 98. An external resonator (EC) is formed by the diffraction grating 71a and the partially reflective coating film PR of the semiconductor light emitting element 30aL. The measurement light 30L emitted from the partially reflective coating film PR enters the gas cell 20.

FIG. 15A and FIG. 15B are schematic views illustrating a part of the gas analyzer according to the embodiment.
These drawings are schematic plan views showing examples of the diffraction grating 71a.
As illustrated in FIGS. 15A and 15B, the diffraction grating 71 has a plurality of regions. In a plurality of regions, the pitch of the grating is different.

  In the example shown in FIG. 15A, the pitch of the grating differs along the X direction. A plurality of regions having different pitches are provided. The resonance wavelength is region rg2> region rg1> region rg3. For example, the wavelength can be adjusted by moving in the X direction.

  In the example shown in FIG. 15B, the resonance wavelengths are region rg5> region rg6> region rg7> region rg4. For example, the diffraction grating 71a is moved along the arrow direction SD illustrated in FIG. Thereby, a wavelength can be adjusted. The cross-sectional shape of the diffraction grating 71a may be asymmetric.

FIG. 16A to FIG. 16C are schematic views illustrating a part of the gas analyzer according to the embodiment.
FIG. 16A is a schematic perspective view. FIG. 16B is a cross-sectional view taken along line A1-A2 of FIG. FIG. 16C is a schematic view illustrating the operation of the light source unit 30.
In this example, a semiconductor light emitting element 30 aL is used as the light source unit 30. A laser is used as the semiconductor light emitting element 30aL. In this example, a quantum cascade laser is used.

  As shown in FIG. 16A, the semiconductor light emitting element 30aL includes a substrate 35, a stacked body 31, a first electrode 34a, a second electrode 34b, a dielectric layer 32 (first dielectric layer), and And an insulating layer 33 (second dielectric layer).

  A substrate 35 is provided between the first electrode 34a and the second electrode 34b. The substrate 35 includes a first portion 35a, a second portion 35b, and a third portion 35c. These parts are arranged in one plane. This plane intersects (for example, parallel) with respect to the direction from the first electrode 34a to the second electrode 34b. A third portion 35c is disposed between the first portion 35a and the second portion 35b.

  The stacked body 31 is provided between the third portion 35c and the first electrode 34a. The dielectric layer 32 is provided between the first portion 35a and the first electrode 34a and between the second portion 35b and the first electrode 34a. An insulating layer 33 is provided between the dielectric layer 32 and the first electrode 34a.

  The stacked body 31 has a stripe shape. The stacked body 31 functions as a ridge waveguide RG. The two end surfaces of the ridge waveguide RG become mirror surfaces. The light 31L emitted from the stacked body 31 is emitted from the end face (light emission surface). The light 31L is an infrared laser beam. The optical axis 31Lx of the light 31L is along the extending direction of the ridge waveguide RG.

  As illustrated in FIG. 16B, the stacked body 31 includes, for example, a first cladding layer 31a, a first guide layer 31b, an active layer 31c, a second guide layer 31d, and a second cladding layer 31e. ,including. These layers are arranged in this order along the direction from the substrate 35 toward the first electrode 34a. Each of the refractive index of the first cladding layer 31a and the refractive index of the second cladding layer 31e is based on the refractive index of the first guide layer 31b, the refractive index of the active layer 31c, and the refractive index of the second guide layer 31d. Is also low. The light 31L generated in the active layer 31c is confined in the stacked body 31. The first guide layer 31b and the first cladding layer 31a may be collectively referred to as a cladding layer. The second guide layer 31d and the second cladding layer 31e may be collectively referred to as a cladding layer.

  The stacked body 31 has a first side surface 31sa and a second side surface 31sb that are perpendicular to the optical axis 31Lx. A distance 31w (width) between the first side surface 31sa and the second side surface 31sb is, for example, not less than 5 μm (micrometer) and not more than 20 μm. Thereby, for example, the control in the horizontal / horizontal mode is facilitated, and the output is easily improved. If the distance 31w is excessively long, a high-order mode is likely to occur in the horizontal and transverse mode, and the output is difficult to increase.

  The refractive index of the dielectric layer 32 is lower than the refractive index of the active layer 31c. Thereby, the ridge waveguide RG is formed by the dielectric layer 32 along the optical axis 31Lx.

  As illustrated in FIG. 16C, the active layer 31c has, for example, a cascade structure. In the cascade structure, for example, the first regions r1 and the second regions r2 are alternately stacked. The unit structure r3 includes a first region r1 and a second region r2. A plurality of unit structures r3 are provided.

  For example, a first barrier layer BL1 and a first quantum well layer WL1 are provided in the first region r1. A second barrier layer BL2 is provided in the second region r2. For example, the third barrier layer BL3 and the second quantum well layer WL2 are provided in another first region r1a. The fourth barrier layer BL4 is provided in another second region r2a.

  In the first region r1, an intersubband optical transition of the first quantum well layer WL1 occurs. Thereby, for example, light 31La having a wavelength of 3 μm or more and 18 μm or less is emitted.

  In the second region r2, the energy of carriers c1 (for example, electrons) injected from the first region r1 can be relaxed.

  In the quantum well layer (for example, the first quantum well layer WL1), the well width WLt is, for example, 5 nm or less. When the well width WLt is so narrow, the energy levels are discrete, and for example, the first subband WLa (high level Lu) and the second subband WLb (low level Ll) are generated. Carriers c1 injected from the first barrier layer BL1 are effectively confined in the first quantum well layer WL1.

  When the carrier c1 transitions from the high level Lu to the low level Ll, light 31La corresponding to the energy difference (difference between the high level Lu and the low level Ll) is emitted. That is, an optical transition occurs.

  Similarly, light 31Lb is emitted from the second quantum well layer WL2 in another first region r1a.

  In the embodiment, the quantum well layer may include a plurality of wells with overlapping wave functions. The high levels Lu of the plurality of quantum well layers may be the same. The low levels Ll of the plurality of quantum well layers may be the same as each other.

  For example, the intersubband optical transition occurs in either the conduction band or the valence band. For example, recombination of holes and electrons by a pn junction is not necessary. For example, an optical transition is caused by either the hole or electron carrier c1, and light is emitted.

  In the active layer 31c, for example, the voltage applied between the first electrode 34a and the second electrode 34b causes the carrier c1 (for example, electrons) to be quantum via the barrier layer (for example, the first barrier layer BL1). Implanted into the well layer (for example, the first quantum well layer WL1). This causes an intersubband optical transition.

  The second region r2 has, for example, a plurality of subbands. The subband is, for example, a miniband. The energy difference in the subband is small. The subband is preferably close to a continuous energy band. As a result, the energy of the carrier c1 (electrons) is relaxed.

  In the second region r2, for example, light (for example, infrared rays having a wavelength of 3 μm to 18 μm) is not substantially emitted. The carriers c1 (electrons) of the low level L1 in the first region r1 pass through the second barrier layer BL2 and are injected into the second region r2 and relaxed. The carrier c1 is injected into another first region r1a that is cascade-connected. An optical transition occurs in this first region r1a.

  In the cascade structure, an optical transition occurs in each of the plurality of unit structures r3. This makes it easy to obtain a high light output in the entire active layer 31c.

  As described above, the light source unit 30 includes the semiconductor light emitting element 30aL. The semiconductor light emitting device 30aL emits the measurement light 30L by energy relaxation of electrons in subbands of a plurality of quantum wells (for example, the first quantum well layer WL1 and the second quantum well layer WL2).

For example, GaAs is used for the quantum well layers (for example, the first quantum well layer WL1 and the second quantum well layer WL2). For example, Al _x Ga _1-x As (0 <x <1) is used for the barrier layer (for example, the first to fourth barrier layers BL1 to BL4, etc.), for example. At this time, for example, when GaAs is used as the substrate 35, good lattice matching is obtained in the quantum well layer and the barrier layer.

The first cladding layer 31a and the second cladding layer 31e include, for example, Si as an n-type impurity. The impurity concentration in these layers is, for example, 1 × 10 ¹⁸ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less (for example, about 6 × 10 ¹⁸ cm ⁻³ ). The thickness of each of these layers is, for example, not less than 0.5 μm and not more than 2 μm (for example, about 1 μm).

The first guide layer 31b and the second guide layer 31d include, for example, Si as an n-type impurity. The impurity concentration in these layers is, for example, 1 × 10 ¹⁶ cm ⁻³ or more and 1 × 10 ¹⁷ cm ⁻³ or less (for example, about 4 × 10 ¹⁶ cm ⁻³ ). The thickness of each of these layers is, for example, 2 μm or more and 5 μm or less (for example, 3.5 μm).

  The distance 31w (the width of the stacked body 31, that is, the width of the active layer 31c) is, for example, 5 μm or more and 20 μm or less (for example, about 14 μm).

  The length of the ridge waveguide RG is, for example, 1 mm or more and 5 mm or less (for example, about 3 mm). The semiconductor light emitting element 30aL operates at an operating voltage of 10 V or less, for example. The current consumption is lower than that of a carbon dioxide laser device or the like. Thereby, operation with low power consumption is possible.

(Third embodiment)
The present embodiment relates to a gas cell. The gas cells described with respect to the above embodiments and modified gas cells thereof are used.

  That is, the gas cell according to the present embodiment (see, for example, FIG. 1A and FIG. 1B) includes a container 23 including a space 23s into which the sample gas 50 is introduced, a light reflective first reflective region 21a, and the like. A first reflective portion 21 including a light transmissive first transmissive region 21b; and a second reflective portion 22 including a light transmissive second reflective region 22a and a light transmissive second transmissive region 22b. . The space 23 s is disposed between the first reflecting portion 21 and the second reflecting portion 22.

  The measurement light 30L enters the space 23s from the first transmission region 21b, is reflected by the first reflection region 21a and the second reflection region 22a, and exits from the second transmission region 22b.

  The relative position of the second transmission region 22b with respect to the first transmission region 21b in the first state ST1 is different from the relative position of the second transmission region 22b with respect to the first transmission region 21b in the second state ST2.

In the first state ST1, the first optical path length of the measurement light 30L from entering the first transmissive region 21b to being emitted from the second transmissive region 22b is incident on the first transmissive region 21b and second transmitted in the second state ST1. This is different from the second optical path length of the measurement light 30L until it exits from the region 22b.
A gas cell capable of dealing with a plurality of substances and capable of highly accurate analysis can be provided.

  In the present embodiment, for example, at least one of the first reflecting unit 21 and the second reflecting unit 22 rotates around the direction from the first reflecting unit 21 toward the second reflecting unit 22 as an axis.

  According to the embodiment, a highly accurate gas analyzer and gas cell can be provided.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, a specific configuration of each element such as a light source unit, a gas cell, a detection unit, a rotation drive unit, a rotation angle sensor, a calculation unit, a wedge substrate, a galvano mirror, and a lens is appropriately selected by those skilled in the art from a known range. Thus, the present invention is included in the scope of the present invention as long as the same effects can be obtained and similar effects can be obtained.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  Based on the gas cell and gas analyzer described above as an embodiment of the present invention, all gas cells and gas analyzers that can be implemented by those skilled in the art with appropriate design changes are also included in the present invention as long as they include the gist of the present invention. Belongs to the range.

In the scope of the idea of the present invention, those skilled in the art can conceive various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention.
For example, those in which the person skilled in the art appropriately added, deleted, or changed the design of the above-described embodiments, or those in which the process was added, omitted, or changed the conditions are also included in the gist of the present invention. As long as it is provided, it is included in the scope of the present invention.

  In addition, other functions and effects brought about by the aspects described in the present embodiment, which are apparent from the description of the present specification, or can be appropriately conceived by those skilled in the art, are naturally understood to be brought by the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 20 ... Gas cell 21, 22 ... 1st, 2nd reflection part, 21a ... 1st reflection area, 21b ... 1st transmission area, 22a ... 2nd reflection area, 22b ... 2nd transmission area, 23 ... Container, 23s ... 30, light source unit, 30L, measuring light, 30a, light emitting unit, 30aC, wavelength control unit, 30aL, semiconductor light emitting element, 30b, drive unit, 31 ... laminate, 31L, 31La, 31Lb, light, 31Lx, light Axis, 31a ... first cladding layer, 31b ... first guide layer, 31c ... active layer, 31d ... second guide layer, 31e ... second cladding layer, 31sa ... first side surface, 31sb ... second side surface, 31w ... distance 32 ... Dielectric layer, 33 ... Insulating layer, 34a ... First electrode, 34b ... Second electrode, 35 ... Substrate, 35a-35c ... First to third parts, 40 ... Detector, 40a ... light-receiving surface, 42a, 42b ... first and second detectors, 45 ... calculation unit, 50 ... sample gas, 53 ... rotation drive unit, 53a ... rotating shaft, 54 ... rotation angle sensor (derivation unit), 54a ... rotation Control unit, 55 ... wedge substrate, 55a, 55b ... first and second substrate, 56: light receiving side galvano mirror unit, 56a, 56b ... mirror unit, 57 ... lens, 58 ... light source side galvano mirror unit, 58a, 58b ... Mirror section, 68 ... pass number monitor, 71 ... diffraction grating, 71a ... diffraction grating, 90 ... temperature control section, 98 ... drive control section, 99 ... stepping motor, ΔVs ... difference, β1-β4 ... angle, γ ... incident angle , Θ: rotation angle, λ: wavelength, λR1 to λR4 ... first to fourth wavelength ranges, 110 to 115, 120, 121 ... gas analyzer, AR ... antireflection coating film, BL1 L4 ... first to fourth barrier layers, Cx ... concentration, G1, G2 ... first and second materials, L1, L2 ... first and second light, Ll ... low level, Lu ... high level, P0 ... Predetermined position, P1, first position, P2, second position, PR, partially reflective coating film, RG, ridge waveguide, SD, arrow direction, ST1, ST2, first, second state, Tr, transmittance, WL1 , WL2 ... first and second quantum well layers, WLa ... first subband, WLb ... second subband, WLt ... well width, c1 ... carriers, r1, r1a ... first reflection region, r2, r2a ... first Transmission region, r3 ... unit structure, rg1-rg7 ... region

Claims (20)

A gas cell including a space into which a sample gas is introduced;
A light source unit for injecting measurement light into the sample gas introduced into the space;
A detection unit for detecting the measurement light emitted from the space;
A first reflecting portion;
A second reflecting portion;
With
The surface of the first reflecting portion that faces the second reflecting portion and the surface of the second reflecting portion that faces the first reflecting portion are in a direction from the first reflecting portion toward the second reflecting portion. Concave and continuous around the axis,
The space is disposed between the first reflecting portion and the second reflecting portion,
The first optical path length of the measurement light until it enters the space in the first state and exits from the space is the second length of the measurement light that enters the space and exits from the space in the second state. Unlike the optical path length,
The gas analyzer according to claim 1, wherein the wavelength of the measurement light in the first state is different from the wavelength of the measurement light in the second state .   The gas analyzer according to claim 1, further comprising a derivation unit that derives a value corresponding to a difference between the first optical path length and the second optical path length.   A calculation unit that further calculates a concentration of a substance contained in the sample gas based on the detection result of the measurement light detected by the detection unit and the value estimated by the deriving unit. Item 3. The gas analyzer according to Item 2. The first reflection unit includes a light reflective first reflective region and a light transmissive first transparent region,
The second reflective portion includes a light reflective second reflective region and a light transmissive second transparent region,
The measurement light enters the space from the first transmission region, is reflected by the first reflection region and the second reflection region, and exits from the second transmission region,
The relative position of the second transmission region in the first state with respect to the first transmission region is different from the relative position of the second transmission region in the second state with respect to the first transmission region,
The first optical path length is a distance from entering the first transmission region and exiting from the second transmission region in the first state,
The gas analysis according to any one of claims 1 to 3, wherein the second optical path length is a distance from entering the first transmission region to exiting from the second transmission region in the second state. apparatus.   5. The gas analyzer according to claim 4, wherein at least one of the first reflection unit and the second reflection unit rotates about a direction from the first reflection unit toward the second reflection unit.   6. The gas analyzer according to claim 4, further comprising a rotation driving unit configured to rotate the second reflecting unit about a direction from the first reflecting unit toward the second reflecting unit.   The gas analyzer according to claim 6, wherein the derivation unit includes a rotation control unit that monitors a rotation angle of the second reflection unit and controls an operation of the rotation driving unit.   The gas analyzer according to claim 6 or 7, wherein the rotation drive unit rotates the detection unit in conjunction with rotation of the second reflection unit. A wedge substrate provided between the second transmission region and the detection unit and having a wedge-shaped cross section;
The wedge substrate rotates around the direction,
The gas analyzer according to claim 6 or 7, wherein the measurement light emitted from the second transmission region passes through the wedge substrate and enters the detection unit. A light receiving side galvanometer mirror provided on the optical path between the second transmission region and the detection unit;
The gas analyzer according to claim 6 or 7, wherein the measurement light emitted from the second transmission region is reflected by the light-receiving side galvanometer mirror unit and is incident on the detection unit. A lens provided on an optical path between the second transmission region and the detection unit;
The gas analyzer according to claim 6 or 7, wherein the measurement light emitted from the second transmission region passes through the lens and enters the detection unit.   The gas analyzer according to claim 6 or 7, wherein an area of a light receiving surface of the detection unit is equal to or larger than an area of a movable region accompanying the rotation of the second transmission region. The detector is
A first detector for detecting the intensity of the measurement light emitted from the second transmission region in the first state;
A second detector for detecting the intensity of the measurement light emitted from the second transmission region in the second state;
The gas analyzer according to claim 6 or 7, comprising:   The first incident angle of the measurement light incident on the space in the first state is different from the second incident angle of the measurement light incident on the space in the second state. The gas analyzer according to one. The first reflection unit includes a light reflective first reflective region and a light transmissive first transparent region,
The second reflective portion includes a light reflective second reflective region and a light transmissive second transparent region,
The measurement light enters the space from the first transmission region, is reflected by the first reflection region and the second reflection region, and exits from the second transmission region,
The first optical path length is a distance from entering the first transmission region at the first incident angle to exiting from the second transmission region,
The gas analyzer according to claim 14, wherein the second optical path length is a distance from entering the first transmission region at the second incident angle to exiting from the second transmission region. The first reflecting part includes a light-reflective reflective region and a light-transmissive transmissive region,
The first optical path length is a distance from entering the transmission region at the first incident angle, reflecting from the second reflection unit, and exiting from the transmission region,
15. The gas analyzer according to claim 14, wherein the second optical path length is a distance from entering the transmission region at the second incident angle, reflecting from the second reflection unit, and exiting from the transmission region. The first reflecting portion includes a light-reflective reflective region and a plurality of light-transmissive transmissive regions,
The first optical path length is incident on one of the plurality of transmission regions at the first incident angle, is reflected by the first reflection unit and the second reflection unit, and is emitted from one of the plurality of transmission regions. Is the distance to
The second optical path length is incident on the one of the plurality of transmission regions at the second incident angle and is reflected by the first reflection unit and the second reflection unit, and is any one of the plurality of transmission regions. The gas analyzer according to claim 14, wherein the gas analyzer is a distance from which the light is emitted.   The light source side galvanometer mirror part which changes the incidence angle of the measurement light which changes the direction of the measurement light radiate | emitted from the said light source part, enters into the said 1st reflection part, and injects into the said space is further provided. Item 18. The gas analyzer according to any one of Items 14 to 17. A container including a space into which a sample gas is introduced;
A first reflective portion including a light reflective first reflective region and a light transmissive first transparent region;
A second reflective portion including a light reflective second reflective region and a light transmissive second transparent region;
With
The surface of the first reflecting portion that faces the second reflecting portion and the surface of the second reflecting portion that faces the first reflecting portion are in a direction from the first reflecting portion toward the second reflecting portion. Concave and continuous around the axis,
The space is disposed between the first reflecting portion and the second reflecting portion,
Measurement light is incident on the space from the first transmission region, reflected by the first reflection region and the second reflection region, and emitted from the second transmission region,
The relative position of the second transmission region in the first state with respect to the first transmission region is different from the relative position of the second transmission region in the second state with respect to the first transmission region,
The first optical path length of the measurement light from entering the first transmission region in the first state to exiting from the second transmission region is incident on the first transmission region in the second state and 2 A gas cell different from the second optical path length of the measurement light until it exits from the transmission region.   20. The gas cell according to claim 19, wherein at least one of the first reflecting portion and the second reflecting portion rotates around a direction from the first reflecting portion toward the second reflecting portion.