Analysis device, analysis method, and program

Abstract

[Problem] To provide a means capable of calibrating an analysis device without being affected by a sample gas or the like in a measurement cell. [Solution] An analysis device 10 comprises a measurement cell 13, a light source 12, a light receiving unit 14, a calculation unit 16, and a calibration mechanism 19. The calibration mechanism 19 includes: a first mirror 41 that reflects light before entering the measurement cell 13; a second mirror 42 that reflects the light reflected by the first mirror 41 toward the light receiving unit 14; and a movement mechanism 45 that moves the first mirror 41 and the second mirror 42 to a first position where, when analyzing the component to be measured, the first mirror 41 and the second mirror 42 do not reflect the light and the light emitted by the light source 12 enters the measurement cell 13, and a second position where, when calibrating the analysis device 10, the first mirror 41 and the second mirror 42 reflect the light from the light source and the light receiving unit receives the light.　

Description

Analysis Device, Analysis Method, and Program

[0001] The present invention relates to an analysis device that irradiates light from a light source to a measurement cell to analyze a sample gas in the measurement cell, an analysis method of the analysis device, and a program.

[0002] Conventionally, a gas analysis device using laser absorption spectroscopy technology has been known (Patent Document 1). In this analysis device, a measurement gas cell for a sample gas is arranged on the optical path of laser light from a laser light source to a photodetector, and the concentration of a measurement target component in the sample gas is calculated based on the detection signal of the photodetector. Further, a calibration gas cell is detachably arranged on the optical path. The calibration gas cell is filled with a measurement target component gas having a known concentration. The wavelength fluctuation data is calibrated based on the detection signal of the photodetector when the calibration gas cell is arranged.

[0003] International Publication No. 2009 / 128138

[0004] The calibration gas cell arranged on the optical path is irradiated with the laser light that has passed through the measurement gas cell. In order to prevent the laser light passing through the measurement gas cell from being affected by the sample gas, it is necessary to replace the sample gas in the measurement gas cell with nitrogen gas or to discharge the sample gas and make the inside of the measurement gas cell in a vacuum state. For example, when continuously analyzing a sample gas in an analysis device, in order to calibrate the wavelength fluctuation data, if the inside of the measurement gas cell is replaced with nitrogen gas or the like, the time required for calibration is long, so there is a problem that the time for continuously analyzing the sample gas also becomes long.

[0005] The present invention has been made in view of these circumstances, and an object thereof is to provide a means capable of calibrating an analysis device without being affected by a sample gas or the like in a measurement cell.

[0006] (1) The present invention relates to an analytical apparatus for analyzing a target component contained in a sample gas. The analytical apparatus comprises a measuring cell into which the sample gas is introduced, a light source for irradiating the measuring cell with light, a light receiving unit for receiving the light emitted from the measuring cell, a calculation unit for calculating the concentration of the target component based on the light received by the light receiving unit, and a calibration mechanism for calibrating the analytical apparatus. The calibration mechanism includes a first mirror for reflecting light before it enters the measuring cell, a second mirror for reflecting the light reflected by the first mirror toward the light receiving unit, a moving mechanism for moving the first mirror and the second mirror to a first position in which the light irradiated by the light source enters the measuring cell without being reflected by the first mirror and the second mirror, and a second position in which the light emitted by the light source is reflected by the first mirror and the second mirror, and the light reflected by the second mirror is received by the light receiving unit.

[0007] When the first and second mirrors are in the first position, light emitted from the light source enters the measurement cell, exits the measurement cell, and reaches the light receiving unit. The light that reaches the light receiving unit undergoes wavelength fluctuations in the measurement cell according to the concentration of the target component contained in the sample gas, so the calculation unit calculates the concentration of the target component based on the light received by the light receiving unit.

[0008] When the first and second mirrors are in the second position, light emitted from the light source is reflected by the first mirror towards the second mirror before it enters the measurement cell. The second mirror reflects the light reflected by the first mirror towards the light receiving unit. Since the light receiving unit receives light that has not passed through the measurement cell, the calculation unit performs calibration based on the light received by the light receiving unit.

[0009] (2) The calibration mechanism may further include an attenuation unit that attenuates the light reflected by the first mirror and the second mirror and received by the light receiving unit.

[0010] The attenuation unit adjusts the intensity of the light that reaches the light-receiving unit without passing through the measurement cell.

[0011] (3) The calculation unit may perform zero calibration based on the output from the light receiving unit when the first mirror and the second mirror are in the second position.

[0012] (4) The calibration mechanism further includes a reference section through which the light reflected by the first mirror is transmitted, and the reference section may have a known absorption peak.

[0013] The reference unit allows light for wavenumber calibration to reach the light receiving unit without passing through the measurement cell.

[0014] (5) The moving mechanism may, when zero-calibrating the analyzer, position the first mirror and the second mirror in the second position and move the reference unit to a third position through which the light reflected by the first mirror does not pass; and when wavenumber-calibrating the analyzer, position the first mirror and the second mirror in the second position and move the reference unit to a fourth position through which the light reflected by the first mirror passes.

[0015] Zero calibration can be performed when the reference unit is in the third position, and wavenumber calibration can be performed when the reference unit is in the fourth position.

[0016] (6) The reference section may be a cell filled with a predetermined gas.

[0017] (7) The calculation unit may perform wavenumber calibration based on the output from the light receiver when the first mirror and the second mirror are in the second position and the reference unit is in the fourth position.

[0018] (8) The measurement cell may be a white cell.

[0019] (9) The measurement cell may be a heliot cell.

[0020] (10) The light source has a plurality of light sources that emit light of different wavelengths, and the reference section may contain a plurality of gases with different absorption peaks.

[0021] (11) The analyzer further comprises a control unit that controls the operation of the moving mechanism, and the control unit may use the moving mechanism to position the first mirror and the second mirror in a first position when analyzing the target component, and use the moving mechanism to position the first mirror and the second mirror in a second position when calibrating the analyzer.

[0022] The operation of the moving mechanism is controlled by the control unit.

[0023] (12) The present invention may also be understood as an analytical method for an analytical apparatus, comprising: a calculation step of introducing a sample gas into a measuring cell, irradiating the measuring cell with light from a light source, having a light receiving unit receive the light emitted from the measuring cell, and calculating the concentration of a target component to be measured contained in the sample gas based on the light received by the light receiving unit; and a calibration step of reflecting the light before it enters the measuring cell with a first mirror, reflecting the light reflected by the first mirror towards the light receiving unit with a second mirror, having the light reflected by the second mirror receive the light receiving unit, and performing calibration based on the light received by the light receiving unit.

[0024] (13) The present invention may also be understood as a program for controlling an analytical device that analyzes a target component contained in a sample gas. The analytical device comprises a measuring cell into which the sample gas is introduced, a light source that irradiates the measuring cell with light, a light receiving unit that receives light emitted from the measuring cell, a calculation unit that calculates the concentration of the target component based on the light received by the light receiving unit, a calibration mechanism for calibrating the analytical device, and a control unit that executes the above program. The calibration mechanism comprises a first mirror that reflects light before it enters the measuring cell, a second mirror that reflects the light reflected by the first mirror toward the light receiving unit, a moving mechanism that moves the first mirror and the second mirror to a first position in which, when analyzing the target component, the light irradiated by the light source enters the measuring cell without being reflected by the first mirror and the second mirror, and to a second position in which, when calibrating the analytical device, the light emitted by the light source is reflected by the first mirror and the second mirror, and the light reflected by the second mirror is received by the light receiving unit. The program causes the control unit to perform an analysis process in which the moving mechanism positions the first mirror and the second mirror at a first position when analyzing the component to be measured, and a calibration process in which the moving mechanism positions the first mirror and the second mirror at a second position when calibrating the analytical device.

[0025] According to the present invention, the analytical instrument can be calibrated without being affected by the sample gas in the measurement cell.

[0026] Figure 1 is a block diagram showing the configuration of the analytical apparatus 10 according to the embodiment. Figure 2(A) is a schematic diagram of the calibration mechanism 19 at the first position viewed from the direction of the path of light, and Figure 2(B) is a schematic diagram showing the II-II cross section of the calibration mechanism 19 at the first position. Figure 3(A) is a schematic diagram of the calibration mechanisms 19 at the second and third positions viewed from the direction of the path of light, and Figure 3(B) is a schematic diagram showing the III-III cross section of the calibration mechanisms 19 at the second and third positions. Figure 4(A) is a schematic diagram of the calibration mechanisms 19 at the second and fourth positions viewed from the direction of the path of light, and Figure 3(B) is a schematic diagram showing the IV-IV cross section of the calibration mechanisms 19 at the second and fourth positions. Figure 5 is a schematic diagram showing a modified calibration mechanism 19 and a heliot cell 60. Figure 6 is a schematic diagram showing a light source having a plurality of semiconductor lasers 71, 72, 73, 74. Figure 7 is a flowchart of the program executed by the control unit 18.

[0027] Preferred embodiments of the present invention will be described below. It goes without saying that these embodiments represent only one aspect of the present invention, and the embodiments can be modified without altering the essence of the invention.

[0028] The analyzer 10 according to this embodiment measures the concentration of a target component contained in a sample gas, and is, for example, an FTIR. As shown in Figure 1, the analyzer 10 includes an interferometer 11, a light source 12, a measurement cell 13, a light receiving unit 14, a plurality of parabolic mirrors 15, a calculation unit 16, a display unit 17, a control unit 18, and a calibration mechanism 19. Although not shown in each figure, the interferometer 11, light source 12, measurement cell 13, light receiving unit 14, the plurality of parabolic mirrors 15, and the calibration mechanism 19 are arranged and fixed in the internal space of the housing of the analyzer 10. The control unit 18 controls the operation of the interferometer 11, light source 12, light receiving unit 14, calculation unit 16, display unit 17, calibration mechanism 19, and / or the movement mechanism 24 of the interferometer 11. The control unit 18 includes, for example, a calculation unit, memory, input unit, display, etc. The memory stores a program that the control unit 18 can execute. The calculation unit 16 may also be implemented as a control unit 18.

[0029] The light source 12 emits infrared light as continuous light with many wavenumbers. For example, a tungsten-iodine lamp or a high-brightness ceramic light source can be used as the light source 12. The infrared light emitted by the light source 12 enters the incident window 31 of the measurement cell 13 via the parabolic mirror 15 and the interferometer 11.

[0030] The measurement cell 13 is a container into which a sample gas is introduced as a sample. The measurement cell 13 has an entrance window 31 and an exit window 32. Infrared light enters the inside of the measurement cell 13 from the entrance window 31, irradiates the sample gas, and is emitted to the outside from the exit window 32. In this embodiment, the sample is an automobile exhaust gas, a factory exhaust gas, a gas in the atmosphere, or a gas generated in a manufacturing process. Although not shown in each figure, the measurement cell 13 has an inlet for introducing the sample gas into the internal space and an outlet for discharging the sample gas from the internal space.

[0031] The measurement cell 13 is a white cell having multiple reflective mirrors 33, 34, and 35. The reflective mirrors 33, 34, and 35 are parabolic mirrors. Reflective mirror 34 is located on the side of the measurement cell 13 where the incident window 31 and the exit window 32 are located in the longitudinal direction, while reflective mirrors 33 and 35 are on the opposite side. Due to the reflective mirrors 33, 34, and 35, infrared light incident on the incident window 31 is reflected a predetermined number of times and emitted from the exit window 32.

[0032] The light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs a fast Fourier transform (FFT) on the detection signal to spectrally analyze it and calculates the light intensity (spectrum) for each wavelength. The obtained light intensity is displayed on the display unit 17 and compared with known light intensities to analyze the composition of the sample gas or the concentration of the target component.

[0033] The interferometer 11 generates interference waves that draw different sine curves for each wavelength from the infrared light emitted from the light source 12. As shown in Figure 1, the interferometer 11 includes a beam splitter 21, a fixed mirror 22, a movable mirror 23, and a moving mechanism 24.

[0034] The beam splitter 21 is a half-mirror that splits the irradiated light into transmitted light and reflected light. An infrared semipermeable film is laminated on the beam splitter 21. In the beam splitter 21, the infrared light emitted from the light source 12 is split into transmitted light and reflected light.

[0035] The fixed mirror 22 is, for example, a corner reflector in which three plane mirrors are arranged so as to be perpendicular to each other. The fixed mirror 22 is fixed at a constant distance from the beam splitter 21. The transmitted light from the beam splitter 21 is reflected in parallel by the fixed mirror 22 with different optical axes.

[0036] The movable mirror 23 is, for example, a corner reflector. The movable mirror 23 moves by a moving mechanism 24 so that its distance from the beam splitter 21 varies. Although not shown in detail in each figure, the moving mechanism 24 includes a guide extending parallel to the reflected light reflected by the beam splitter 21, a trolley that moves along the guide, and an actuator that moves the trolley. The actuator is, for example, a voice coil motor. The movable mirror 23 moves while mounted on the trolley, causing its distance from the beam splitter 21 to vary.

[0037] Infrared light emitted from the light source 12 is split by the beam splitter 21. The fixed mirror 22 reflects the transmitted light back to the beam splitter 21. The movable mirror 23 reflects the reflected light back to the beam splitter 21. The movable mirror 23 reciprocates by the movement mechanism 24. As a result, the reflected light reflected by the movable mirror 23 and returned to the beam splitter 21 and the transmitted light reflected by the fixed mirror 22 and returned to the beam splitter 21 are combined as an interference wave of infrared light. The interference wave draws a different sine curve for each wavelength. The interference wave is reflected by the parabolic mirror 15 and incident on the measurement cell 13. The interference wave emitted from the measurement cell 13 is reflected by the parabolic mirror 15 and incident on the light receiving unit 14. Note that the parabolic mirror 15 is not an essential component and may be omitted if it is not necessary to fold back the optical path of the infrared light.

[0038] As shown in Figure 1, the calibration mechanism 19 is located adjacent to the measurement cell 13. As shown in Figures 2(A) and 2(B), the calibration mechanism 19 includes a housing 40, a first mirror 41, a second mirror 42, an attenuation unit 43, a reference cell 44, and a moving mechanism 45. The first mirror 41, the second mirror 42, the attenuation unit 43, the reference cell 44, and the moving mechanism 45 are located in the internal space of the housing 40.

[0039] The internal space of the housing 40 is filled with nitrogen gas or is under vacuum. The housing 40 has two inlet windows 47 and two outlet windows 48. The two inlet windows 47 and the two outlet windows 48 transmit infrared light. The two inlet windows 47 are located on the optical path of infrared light incident on the measurement cell 13, on opposing walls of the housing 40. The inlet window 47 located closer to the measurement cell 13 faces the inlet window 31 of the measurement cell 13. The two outlet windows 48 are located on the optical path of infrared light emitted from the measurement cell 13, on opposing walls of the housing. The outlet window 48 located closer to the measurement cell 13 faces the outlet window 32 of the measurement cell 13.

[0040] The first mirror 41, the second mirror 42, the damping unit 43, and the reference cell 44 are mounted on the moving mechanism 45. The moving mechanism 45 has an axis 49, a first support plate 50, and a second support plate 51. The first support plate 50 and the second support plate 51 rotate about the axis 49 in the internal space of the housing 40. Although not shown in the figures, the first support plate 50 and the second support plate 51 rotate, for example, by the transmission of driving force from a motor. The first support plate 50 rotates to a first position not located between the two inlet windows 47 and the outlet window 48, and to a second position located between the two inlet windows 47 and the outlet window 48. Driving force is transmitted to the moving mechanism 45 from a drive source, for example, a motor driven based on a drive signal controlled by the control unit 18.

[0041] The first support plate 50 supports the first mirror 41, the second mirror 42, and the attenuation section 43. As shown in FIGS. 3(A) and 3(B), when the first support plate 50 is in the second position, the first mirror 41 faces the incident window 47 that transmits the infrared light incident on the housing 40. The second mirror 42 faces the emission window 48 that transmits the infrared light emitted from the housing 40. The attenuation section 43 is located between the first mirror 41 and the second mirror 42. The first mirror 41 and the second mirror 42 are planar mirrors that reflect infrared light. The attenuation section 43 is a filter or iris that attenuates the intensity of infrared light.

[0042] As shown in FIGS. 2(A) and 2(B), when the first support plate 50 is in the first position, the infrared light incident on the housing 40 from the incident window 47 passes through the opposing incident window 47 and enters the incident window 31 of the measurement cell 13. The infrared light emitted from the emission window 32 of the measurement cell 13 passes through the emission window 48, passes through the housing 40, passes through the opposing emission window 48, and is emitted from the housing 40.

[0043] When the first support plate 50 is in the second position, the infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41 and travels toward the attenuation section 43. By passing through the attenuation section 43, the intensity of the reflected infrared light is attenuated. The attenuation section 43 is set to an attenuation rate corresponding to the optical path difference when the infrared light passes through the measurement cell 13 and when it does not pass through the measurement cell 13, for example. The infrared light that has passed through the attenuation section 43 is reflected by the second mirror 42 toward the emission window 48 and is emitted from the housing 40.

[0044] The second support plate 51 supports the reference cell 44. The second support plate 51 rotates between a third position where the reference cell 44 is not located between the first mirror 41 and the second mirror 42 and a fourth position where the reference cell 44 is located between the first mirror 41 and the second mirror 42 when the first support plate 50 is in the second position.

[0045] The reference cell 44 is a transmission-type cell in which a plurality of gas components having known and different absorption peaks are enclosed. Examples of the plurality of gas components to be enclosed include methane gas at a predetermined concentration.

[0046] As shown in FIGS. 2(A) and 2(B), when the first support plate 50 is in the first position, the second support plate 51 is located in the third position. By abutting against the first mirror 41 supported by the first support plate 50 in the first position, the second support plate 51 cannot rotate toward the fourth position.

[0047] As shown in FIGS. 3(A) and 3(B), when the first support plate 50 is in the second position and the second support plate 51 is in the third position, as described above, the infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41, passes through the attenuation portion 43, is reflected by the second mirror 42, and is emitted from the emission window 48 to the outside of the housing 40. Since the second support plate 51 is in the third position, the infrared light incident on and emitted from the housing 40 does not pass through the reference cell 44.

[0048] As shown in FIGS. 4(A) and 4(B), when the first support plate 50 is in the second position and the second support plate 51 is in the fourth position, the infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41 and passes through the reference cell 44. The positions of the first mirror 41 and the second mirror 42 are adjusted so as to condense on the center of the reference cell 44. By passing through the reference cell 44, a specific wavelength of the infrared light is absorbed. The infrared light that has passed through the reference cell 44 passes through the attenuation portion 43, is reflected by the second mirror 42, and is emitted from the emission window 48 to the outside of the housing 40.

[0049] When analyzing the sample gas using the measurement cell 13, as shown in FIGS. 2(A) and 2(B), the moving mechanism 45 positions the first support plate 50 in the first position and positions the second support plate 51 in the third position. Further, the sample gas to be analyzed is introduced into the measurement cell 13. The infrared light irradiated from the light source 12 and made into an interference wave by the interferometer 11 enters the calibration mechanism 19.

[0050] Infrared light entering the housing 40 from the entrance window 47 passes through the opposite entrance window 47 and enters the entrance window 31 of the measurement cell 13. The infrared light, which is reflected multiple times in the measurement cell 13 and absorbed at specific wavelengths by the components of the sample gas to be analyzed, exits from the exit window 32 of the measurement cell 13, passes through the exit window 48 and through the housing 40, and exits from the housing 40 after passing through the opposite exit window 48.

[0051] The light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs a fast Fourier transform (FFT) on the detection signal to spectrally analyze it and calculates the light intensity (spectrum) for each wavelength. The obtained light intensity is displayed on the display unit 17 and compared with known light intensities to analyze the composition of the sample gas or the concentration of the target component.

[0052] When zero calibration of the analyzer 10 is performed using the calibration mechanism 19, the moving mechanism 45 positions the first support plate in the second position and the second support plate 51 in the third position, as shown in Figures 3(A) and 3(B). At this time, the internal space of the measurement cell 13 may contain the sample gas to be analyzed. In other words, it is not necessary to fill the measurement cell 13 with nitrogen gas or to create a vacuum.

[0053] Infrared light emitted from the light source 12 and converted into an interference wave by the interferometer 11 is incident on the calibration mechanism 19. Infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41, passes through the attenuation section 43, is reflected by the second mirror 42, and is emitted outside the housing 40 from the exit window 48.

[0054] The light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs zero calibration, i.e., background spectrum calibration, based on the detection signal.

[0055] When wavenumber calibration of the analyzer 10 is performed using the calibration mechanism 19, the moving mechanism 45 positions the first support plate at the second position and the second support plate 51 at the fourth position, as shown in Figures 4(A) and 4(B). At this time, the internal space of the measurement cell 13 may contain the sample gas to be analyzed. In other words, it is not necessary to fill the measurement cell 13 with nitrogen gas or to create a vacuum.

[0056] Infrared light emitted from the light source 12 and converted into an interference wave by the interferometer 11 is incident on the calibration mechanism 19. The infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41, passes through the reference cell 44, then passes through the attenuation section 43, is reflected by the second mirror 42, and is emitted to the outside of the housing 40 from the exit window 48.

[0057] The light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs wavenumber calibration based on the detection signal.

[0058] The operation of the analyzer 10 by the program executed by the control unit 18 will be described below with reference to Figure 7. The following operation is an example of the analysis method of the analyzer 10. The control unit 18 displays a screen on the display asking whether or not to perform calibration and waits for user input. At this time, the measurement cell 13 may contain the sample gas to be measured or a sample gas that has already been analyzed, or the sample gas may have been discharged from the measurement cell 13 and air or other gas may be present. In other words, any gas may be present in the measurement cell 13 when calibration is performed. In this embodiment, in the initial state, the first support plate 50 is in the first position and the second support plate 51 is in the third position (see Figures 2(A) and 2(B)).

[0059] If the user inputs to the control unit 18 that they want to perform calibration (S10: Yes), the control unit 18 displays a screen on the display asking whether or not to perform zero calibration and waits for user input. If the user inputs to the control unit 18 that they do not want to perform calibration (S10: No), the process proceeds to step S21.

[0060] If the user inputs to the control unit 18 that zero calibration should be performed (S11: Yes), the control unit 18 drives the moving mechanism 45 to move the first support plate 50 to the second position (S12) and the second support plate 51 to the third position (S13), as shown in Figures 3(A) and 3(B). If the user inputs to the control unit 18 that zero calibration should not be performed (S11: No), the process proceeds to step S16.

[0061] Subsequently, the control unit 18 emits light from the light source (S14). As shown in Figure 1, the light emitted from the light source is converted into an interference wave by the interferometer 11 and incident on the calibration mechanism 19. As shown in Figure 3(B), the infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41, passes through the attenuation unit 43, is reflected by the second mirror 42, and is emitted to the outside of the housing 40 from the exit window 48.

[0062] As shown in Figure 1, the light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs zero calibration based on the detection signal (S15).

[0063] Next, the control unit 18 displays a screen on the display asking whether or not to perform wavenumber calibration, and waits for user input. If the user inputs to the control unit 18 that they want to perform wavenumber calibration (S16: Yes), the control unit 18 drives the moving mechanism 45 to position the first support plate 50 in the second position (S17) and move the second support plate 51 to the fourth position (S18), as shown in Figures 4(A) and 4(B). If the user inputs to the control unit 18 that they do not want to perform wavenumber calibration (S16: No), the process proceeds to step S21.

[0064] Subsequently, the control unit 18 emits light from the light source (S19). As shown in Figure 1, the light emitted from the light source is converted into an interference wave by the interferometer 11 and incident on the calibration mechanism 19. As shown in Figure 4(B), the infrared light incident on the housing 40 from the incident window 47 is reflected by the first mirror 41, passes through the reference cell 44, then passes through the attenuation unit 43, is reflected by the second mirror 42, and is emitted to the outside of the housing 40 from the exit window 48.

[0065] As shown in Figure 1, the light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs wavenumber calibration based on the detection signal (S20). The process from step S10 to step S20 is an example of the calibration process and calibration steps.

[0066] Next, the control unit 18 displays a screen on the display asking whether or not to perform concentration analysis, and waits for user input. If the user inputs to the control unit 18 that they want to perform concentration analysis (S21: Yes), the control unit 18 drives the moving mechanism 45 to move the first support plate 50 to the first position (S22) and the second support plate 51 to the third position (S23), as shown in Figures 2(A) and 2(B). If the user inputs to the control unit 18 that they do not want to perform concentration analysis (S21: No), the program terminates.

[0067] Subsequently, the control unit 18 irradiates light from the light source (S24). If the sample gas, which is the sample, has not been introduced into the measurement cell 13, the sample gas is introduced into the measurement cell 13 before light is irradiated from the light source. As shown in Figure 1, the light irradiated from the light source 12 is converted into an interference wave by the interferometer 11 and incident on the calibration mechanism 19.

[0068] As shown in Figure 2(B), infrared light entering the housing 40 from the entrance window 47 passes through the opposite entrance window 47 and enters the entrance window 31 of the measurement cell 13. The infrared light, which is reflected multiple times in the measurement cell 13 and has specific wavelengths absorbed by the components of the sample gas, exits from the exit window 32 of the measurement cell 13, passes through the exit window 48 and the housing 40, and exits from the housing 40 after passing through the opposite exit window 48.

[0069] As shown in Figure 1, the light receiving unit 14 receives infrared light emitted from the calibration mechanism 19 and outputs a detection signal to the calculation unit 16. The calculation unit 16 performs a fast Fourier transform on the detection signal to spectrally analyze it and calculates the light intensity (spectrum) for each wavelength. The obtained light intensity is displayed on the display unit 17 and compared with known light intensities to analyze the composition of the sample gas or the concentration of the target component. After that, the program terminates. The process from step S21 to step S25 is an example of the analysis process and calculation steps.

[0070] [Effects of this embodiment] The moving mechanism 45 positions the first support plate at the second position and the second support plate 51 at the third position, thereby enabling zero calibration even if the sample gas to be analyzed is present in the internal space of the measurement cell 13.

[0071] Furthermore, the attenuation unit 43 adjusts the intensity of the light that reaches the light receiving unit 14 without passing through the measurement cell 13.

[0072] Furthermore, by having the moving mechanism 45 position the first support plate at the second position and the second support plate 51 at the fourth position, wavenumber calibration can be performed even if the sample gas to be analyzed is present in the internal space of the measurement cell 13.

[0073] [Modifications] In the embodiment described above, the reference cell 44 contained multiple gases with different absorption peaks, but the reference cell 44 may contain only one gas. Also, in the embodiment described above, the reference cell 44 was used as the reference unit, but instead of the reference cell 44, a filter that absorbs a specific wavelength may be used. Furthermore, the attenuation unit 43 may be provided as needed and may be omitted. In addition, the program stored in the control unit 18 does not necessarily have to query whether to perform calibration (S10), whether to perform zero calibration (S11), and whether to perform wavenumber calibration (S16). For example, the control unit 18 may display an input for performing calibration, and the user may input to perform calibration at any time as needed. Furthermore, calibration and analysis in the analyzer 10 do not have to be performed by a program stored in the control unit 18. For example, calibration and analysis may be performed in response to each operation of the user. In that case, the control unit 18 may be omitted.

[0074] Furthermore, although an FTIR was exemplified as the analytical apparatus in the embodiments described above, the analytical apparatus is not limited to an FTIR and may be other types of gas analyzers. In that case, the light source 12 may emit not only infrared light, but also X-rays, ultraviolet light, visible light, near-infrared light, or microwaves (i.e., light). Alternatively, instead of an infrared light emitter, the light source 12 may be a semiconductor laser, a gas laser such as a He-Ne laser, a solid-state laser such as a YAG laser, a fiber laser, or a liquid laser such as a dye laser.

[0075] Furthermore, a heliot cell may be used instead of a white cell for the measurement cell 13. When a heliot cell is used, as shown in Figure 5, light from a light source is incident on the inlet / outlet window 61 of the heliot cell 60 at a predetermined incident angle. The incident light is multiple-reflected by the mirrors 62 and 63, which are arranged opposite each other within the heliot cell 60, and the light is emitted from the inlet / outlet window 61 at a predetermined exit angle. In Figure 5, the propagation of light when the first mirror 41 and the second mirror 42 of the calibration mechanism 19 are in the first position is shown by a dashed line.

[0076] The calibration mechanism 19 is positioned adjacent to the inlet / outlet window 61 of the heliot cell 60. The configuration of the calibration mechanism 19 is the same as in the previously described embodiment, but one inlet / outlet window 53 is positioned in the housing 40 opposite the inlet / outlet window 61 of the heliot cell 60. In addition, the reflection angles of the first mirror 41 and the second mirror 42 are adjusted according to the incident angle and the exit angle. In Figure 5, the propagation of light when the first mirror 41 and the second mirror 42 are in the second position is shown by solid lines.

[0077] Furthermore, although the light source 12 was single in the embodiment described above, the analyzer may have multiple light sources. For example, as shown in Figure 6, four semiconductor lasers 71, 72, 73, and 74 with different oscillation wavelengths may be used as light sources, and the laser light synthesized by the optical system 75 may be incident on the calibration mechanism 19. The optical system 75 has four reflective mirrors corresponding to each semiconductor laser 71, 72, 73, and 74, and the laser light reflected by each of the four reflective mirrors exits the optical system through the same optical path. In this case, the reference cell 44 is filled with multiple types of gases corresponding to the wavelengths of the multiple semiconductor lasers 71, 72, 73, and 74.

[0078] Furthermore, in the embodiment described above, the moving mechanism 45 moved the positions of the first mirror 41 and the second mirror 42 by rotation, but the positions of the first mirror 41 and the second mirror 42 may be moved by sliding instead of rotation. Similarly, the movement of the reference cell 44 may be by sliding instead of rotation.

[0079] 10...Analytical device 12...Light source 13...Measurement cell 14...Light receiving unit 16...Calculation unit 18...Control unit 19...Calibration mechanism 41...First mirror 42...Second mirror 43...Attenuation unit 44...Reference cell (reference unit) 45...Movement mechanism 60...Heliot cell (measurement cell) 71, 72, 73, 74...Semiconductor laser (light source)

Claims

1. An analytical apparatus for analyzing a target component contained in a sample gas, comprising: a measuring cell into which the sample gas is introduced; a light source for irradiating the measuring cell with light; a light receiving unit for receiving light emitted from the measuring cell; a calculation unit for calculating the concentration of the target component based on the light received by the light receiving unit; and a calibration mechanism for calibrating the analytical apparatus, wherein the calibration mechanism comprises: a first mirror for reflecting light before it enters the measuring cell; a second mirror for reflecting the light reflected by the first mirror toward the light receiving unit; a moving mechanism for moving the first mirror and the second mirror to a first position in which light irradiated by the light source enters the measuring cell without being reflected by the first mirror and the second mirror; and a second position in which the light emitted by the light source is reflected by the first mirror and the second mirror, and the light reflected by the second mirror is received by the light receiving unit.

2. The analytical apparatus according to claim 1, wherein the calibration mechanism further comprises an attenuation unit that attenuates the light reflected by the first mirror and the second mirror and received by the light receiving unit.

3. The analytical apparatus according to claim 1 or 2, wherein the calculation unit performs zero calibration based on the output from the light receiving unit when the first mirror and the second mirror are in the second position.

4. The analytical apparatus according to any one of claims 1 to 3, wherein the calibration mechanism further comprises a reference section through which light reflected by the first mirror is transmitted, and the reference section has a known absorption peak.

5. The analytical apparatus according to claim 4, wherein the moving mechanism, when zero-calibrating the analytical apparatus, positions the first mirror and the second mirror in the second position and moves the reference section to a third position through which light reflected by the first mirror does not pass; and when wavenumber-calibrating the analytical apparatus, positions the first mirror and the second mirror in the second position and moves the reference section to a fourth position through which light reflected by the first mirror passes.

6. The analytical apparatus according to claim 4, wherein the reference section is a cell filled with a predetermined gas.

7. The analytical apparatus according to claim 5, wherein the calculation unit performs wavenumber calibration based on the output from the light receiver when the first mirror and the second mirror are in the second position and the reference unit is in the fourth position.

8. The analytical apparatus according to any one of claims 1 to 7, wherein the measuring cell is a white cell.

9. The analytical apparatus according to any one of claims 1 to 7, wherein the measuring cell is a heliot cell.

10. The analytical apparatus according to claim 4 or 6, wherein the light source has a plurality of light sources that emit light of different wavelengths, and the reference section is filled with a plurality of gases with different absorption peaks.

11. The analytical apparatus according to any one of claims 1 to 10, further comprising a control unit for controlling the operation of the moving mechanism, wherein the control unit moves the first mirror and the second mirror to a first position by the moving mechanism when analyzing the component to be measured, and moves the first mirror and the second mirror to a second position by the moving mechanism when calibrating the analytical apparatus.

12. An analytical method for an analytical apparatus, comprising: a calculation step of introducing a sample gas into a measuring cell, irradiating the measuring cell with light from a light source, having a light receiving unit receive the light emitted from the measuring cell, and calculating the concentration of a target component to be measured in the sample gas based on the light received by the light receiving unit; and a calibration step of reflecting the light before it enters the measuring cell with a first mirror, reflecting the light reflected by the first mirror with a second mirror toward the light receiving unit, having the light reflected by the second mirror received by the light receiving unit, and performing calibration based on the light received by the light receiving unit.

13. A program for controlling an analytical apparatus for analyzing a target component contained in a sample gas, wherein the analytical apparatus comprises: a measuring cell into which the sample gas is introduced; a light source for irradiating the measuring cell with light; a light receiving unit for receiving light emitted from the measuring cell; a calculation unit for calculating the concentration of the target component based on the light received by the light receiving unit; a calibration mechanism for calibrating the analytical apparatus; and a control unit for executing the program, wherein the calibration mechanism comprises: a first mirror for reflecting light before it enters the measuring cell; a second mirror for reflecting the light reflected by the first mirror toward the light receiving unit; a moving mechanism for moving the first and second mirrors to a first position in which, when analyzing the target component, the light irradiated by the light source enters the measuring cell without being reflected by the first and second mirrors; and a second position in which, when calibrating the analytical apparatus, the light emitted by the light source is reflected by the first and second mirrors, and the light reflected by the second mirror is received by the light receiving unit. The program causes the control unit to perform an analysis process in which, when analyzing the component to be measured, the moving mechanism positions the first mirror and the second mirror at a first position, and a calibration process in which, when calibrating the analytical device, the moving mechanism positions the first mirror and the second mirror at a second position.

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