JP5848791B2 - Exhalation diagnostic device - Google Patents

Description

  Embodiments described herein relate generally to a breath diagnosis apparatus.

  Laser devices that emit infrared light are applied to a wide range of fields such as environmental measurement and gas concentration measurement.

  Many gases absorb infrared radiation according to their intrinsic absorption spectrum. The absorbance depends on the gas concentration, but can be determined by measuring the transmission intensity with respect to the incident intensity of infrared light. Therefore, by measuring the infrared light transmission intensity in the gas whose concentration is to be known, the concentration of the gas can be known from the previously determined absorbance.

  One of the applications can be a breath diagnosis apparatus. That is, human exhalation contains various gases, so if the gas concentration of exhalation can be measured, disease prevention and early detection are facilitated.

  However, in general, an infrared light source is a large-sized device that consumes a large amount of power, such as a carbon dioxide laser device or a Raman laser device, and the breath diagnosis device is also enlarged.

Japanese Patent No. 4108297 JP 2007-30980 A

  Provided is a breath diagnosis apparatus that is small in size and easy to reduce power consumption.

Breath diagnosis apparatus embodiment is a measurable breath diagnosis device concentrations of a plurality of types of gas contained in the breath, having one end surface of the reflecting coating film is provided, the electrons in the plurality of quantum wells A quantum cascade laser that emits infrared light by intersubband transition; a first adjustment mechanism that shifts the wavelength of the infrared light into an absorption spectrum of one of the plurality of gases; and the red A wavelength control unit having a second adjustment mechanism that shifts the wavelength of external light within the absorption spectrum of one kind of gas, an exhalation intake port, an exhalation discharge port, the infrared light incident window, and the infrared light An emission window that is emitted as transmitted light without being absorbed by the exhalation, a detection unit that detects the intensity of the infrared light, the intensity of the incident light to the incident window, and the transmission from the intensity of the light, the Comprising a signal processing unit for calculating the concentration of several gases, and the reflectivity of the reflective coating film when the light output of the transmitted light becomes the maximum value expressed as Rp, according to the reflectance increases When the reflectance when the light output of the transmitted light is reduced to half of the maximum value is expressed as R _{-3 dB} , the reflectance of the reflective coating film is equal to or greater than Rp in the wavelength range of the infrared light. And R _{−3 dB} or less .

1A is a configuration diagram of the breath diagnosis apparatus according to the first embodiment, FIG. 1B is a schematic diagram of absorption spectra of a plurality of gases, FIG. 1C is a first adjustment mechanism for wavelength control, and FIG. It is a figure explaining a 2nd adjustment mechanism. It is a figure showing the relationship between a trace gas and the wavelength of infrared light required in order to detect this. It is a graph showing the dependence of the degree of absorption on the wave number (reciprocal of wavelength) of ammonia, carbon dioxide, and water. It is a flowchart of the expiration measurement. It is a graph showing an example of the absorption spectrum of measured gas. It is a flowchart concerning the 1st modification of expiration measurement. It is a flowchart concerning the 2nd modification of expiration measurement. 8A shows a first modification of the first adjustment mechanism, FIG. 8B shows a second modification thereof, and FIG. 8C shows a third modification thereof. FIG. 9A is a configuration diagram of the breath diagnosis apparatus according to the second embodiment, and FIG. 9B is a block diagram of the breath diagnosis apparatus according to the third embodiment. FIG. 10A is a schematic perspective view in which the quantum cascade laser is partially cut, and FIG. 10B is a schematic cross-sectional view taken along the line AA. FIG. 11A is a configuration diagram of the breath diagnosis apparatus according to the fourth embodiment, FIG. 11B is a schematic diagram in the vicinity of the external resonator, and FIG. 11C is a relative output with respect to the reflectance of the partial reflection coating film. It is a graph explaining the dependence of electric power. FIGS. 12A and 12B are schematic plan views of a diffraction grating used in the breath diagnosis apparatus according to the fourth embodiment. It is a band figure explaining the effect | action of a quantum cascade laser.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a configuration diagram of the breath diagnosis apparatus according to the first embodiment, FIG. 1B is a schematic diagram of absorption spectra of a plurality of gases, and FIG. 1C is a first adjustment mechanism of a wavelength controller. It is a figure explaining a 2nd adjustment mechanism.
The breath diagnosis apparatus includes a semiconductor light emitting element including a quantum cascade laser 70, a wavelength control unit, a gas cell (corresponding to “casing”) 80, a detection unit 87, and a signal processing unit 88. The semiconductor light emitting element and the wavelength control unit can be referred to as a light source unit 91.

  The wavelength control unit includes a first adjustment mechanism that shifts the wavelength of emitted light including infrared laser light and the like into an absorption spectrum of one type of gas included in exhaled gas such as a human, and one type And a second adjustment mechanism that shifts in the absorption spectrum of the gas.

  In the first embodiment, the first adjustment mechanism includes a diffraction grating 71. The diffraction grating 71 is provided so as to intersect the optical axis 62 of the quantum cascade laser 70 and constitutes an external resonator. As shown in FIG. 1C, in the breath BR including a plurality of gases, the incident angle of the infrared laser beam is changed to β1 to β4 or the like according to the absorption spectrum of each gas, and the wavelength of the infrared laser beam is changed. (Coarse adjustment) The diffraction grating 71 is rotationally controlled around an axis that intersects the optical axis 62 by a stepping motor 99 and a controller 98 that controls the diffraction grating 71. In addition, it is preferable to provide a non-reflective coating film AR on the end face of the quantum cascade laser 70 on the diffraction grating 71 side. Further, when a partial reflection coating film PR is provided on the side opposite to the non-reflective coating film AR, an external resonator can be formed with the diffraction grating 71.

In order to improve the measurement accuracy because the molecular absorption spectrum is discrete, it is necessary to accurately match the wavelength with the absorption peak. Further, in order to avoid absorption of carbon dioxide and water, which are main components in exhalation, and to measure absorption of a molecule to be measured, it is necessary to accurately match the wavelength to the absorption peak. However, the absorption peak of the molecule and the wavelength of the light source may be affected and shifted due to the measurement environment. For this reason, it is preferable to perform fine adjustment using the second adjustment mechanism. Further, as shown in FIG. 1C, the second adjustment mechanism keeps the diffraction grating 71 constant without rotating it. The wavelength adjustment is performed by changing the operating current value I _LD or duty of the quantum cascade laser 70, changing the operating temperature of the quantum cascade laser 70 using the Peltier element 90, or changing the external resonator length by a piezo element or the like. It can be realized by, for example. Alternatively, the second adjustment mechanism may change the operating temperature of the quantum cascade laser 70 by any one or a combination of a chiller, a heater, and a refrigerant. The refrigerant can be, for example, liquid nitrogen, water, ethanol water, or liquid helium.

  As shown in FIG. 1B, for example, the gas concentrations of acetone (absorption peak on the vertical axis is near 7.37 μm) and methane (absorption peak is near 7.7 μm) are measured. To do. The absorption spectra of different gases are largely separated from each other, for example, approximately 0.3 μm. For this reason, in order to measure a plurality of gases in a short time (for example, 1 minute), it is preferable to quickly increase the wavelength of the infrared laser light and increase the shift width by the first adjustment mechanism.

  On the other hand, in the second adjustment mechanism, when wavelength adjustment is performed within the absorption spectrum of one gas, the shift width may be narrower than the wavelength range in the first adjustment mechanism. However, it is required to increase the adjustment accuracy. That is, it is not easy to realize the first adjustment mechanism that is mainly coarse adjustment and the second adjustment mechanism that is mainly fine adjustment with the same wavelength control mechanism.

  The gas cell 80 includes an exhalation suction port 81, an exhalation discharge port 82, an infrared laser light incident window 83, and an infrared laser light emission window 84. The laser beam from the quantum cascade laser 70 has a divergence angle. For this reason, the collimating optical system 72 is provided between the quantum cascade laser 70 and the incident window 83. A condensing optical system 86 may be provided between the exit window 84 and the detector 87.

The detector 87 detects the intensity of the infrared laser beam. In addition, when the incident light intensity of the infrared laser light incident on the incident window 83 of the gas cell 80 is I ₀ and the transmission intensity of the laser light emitted from the emission window 84 is I, the absorbance A is expressed by Expression (1). be able to. The incident light intensity Io can be measured by replacing the inside of the gas cell 80 with the atmosphere and irradiating with infrared laser light.

  By measuring the transmission intensity I with the detector 87, the signal processing unit 88 calculates the partial pressure Pa (that is, the gas concentration) of the gas from the equation (1).

  Human breath BR contains nitrogen, oxygen, carbon dioxide, water, and the like as main components. At the same time, 1000 or more kinds of different molecules are contained in a very small amount, and a change in a very small amount of gas becomes an indicator of a disease. For this reason, if the trace gas G1 contained in the exhalation is measured, it becomes possible to detect and prevent the disease early. By using the breath diagnosis apparatus in this way, it is possible to make a diagnosis in a short time and more easily than performing a blood test or the like.

  For example, diabetes can be found if acetone can be detected as the trace gas G1. In this case, detection sensitivity of about ppm is required using infrared rays having a wavelength of 7 to 8 μm. Moreover, hepatitis can be discovered if ammonia can be detected as a trace gas. In this case, detection sensitivity of about ppb is required using infrared rays having a wavelength of 10.3 μm. If ethanol or acetaldehyde can be detected as a trace gas, the amount of drinking can be measured.

FIG. 2 is a diagram showing the relationship between the wavelength of infrared light necessary to detect a trace gas and the amount of absorbed infrared light.
When the wavelength of the quantum cascade laser is 4 to 11 μm, most of the light absorption spectrum of the trace gas can be detected.

FIG. 3 is a graph showing the dependence of the absorbance on the wave number (reciprocal of wavelength) of ammonia, carbon dioxide, and water.
The vertical axis represents Absorption (absorption amount) × 10 ⁻³ (%), and the horizontal axis represents the wave number (reciprocal of wavelength) (cm ⁻¹ ). For example, for 10 ppb NH ₃ , 5% CO ₂ , 5% H ₂ O mixed gas, etc., the light absorption of only ammonia is obtained by fine tuning the light source to the absorption wavelength of ammonia in the narrow spectrum of the quantum cascade laser. It is possible.

FIG. 4 is a flowchart of the exhalation measurement.
First, the breath diagnosis apparatus is turned on. At this time, the quantum cascade laser 70 can also be turned on. Next, the gas cell 80 is evacuated and replaced with, for example, the atmosphere (S100).

  Subsequently, the wavelength of the quantum cascade laser 70 is roughly adjusted within the absorption spectrum of the first gas by the first adjustment mechanism (S102).

  Subsequently, the second adjustment mechanism finely adjusts the wavelength of the quantum cascade laser 70 to the vicinity of the absorption peak value of the absorption spectrum of the first gas. The detector 87 measures the transmission intensity of the infrared laser beam that has passed through the atmosphere (equal to the incident light intensity Io incident on the incident window 83) and sets it as a reference signal value (S104).

  Subsequently, it is determined whether there is a gas to be measured next. If YES, the process returns to step S102 and the reference signal value of the second gas is measured. If NO, the measurement of the reference signal value is terminated (S106).

  Subsequently, exhalation is blown (S108).

  Subsequently, the wavelength of the quantum cascade laser 70 is roughly adjusted in the measured gas absorption spectrum by the first adjustment mechanism (S110).

  Subsequently, the second adjustment mechanism finely adjusts the wavelength of the quantum cascade laser 70 to the vicinity of the absorption peak value of the absorption spectrum of the first gas. The detector 87 measures the transmission intensity I of the infrared laser beam that has passed through the breath in the gas cell 80 and sets it as the measured gas signal value (S112).

  Subsequently, it is determined whether there is a gas to be measured next. If YES, the process returns to step 110. If NO, the measurement of the gas signal value to be measured is terminated (S114).

FIG. 5 is a graph showing an example of the absorption spectrum of the gas to be measured.
The vertical axis represents the relative absorption amount, and the horizontal axis represents the wavelength (μm). The first gas is acetone, and the second gas is methane. The absorption peak of acetone is near 7.35 μm in wavelength. The absorption peak of methane has a wavelength in the vicinity of 7.63 μm. Therefore, when acetone and methane are contained as in exhalation, an absorption spectrum in which both are added is obtained.

  For example, the acetone gas absorbance A can be calculated by the equation (1) using the acetone gas signal value and the acetone reference signal value measured by fine adjustment to around 7.35 μm by the second adjustment mechanism (S116). Further, the methane gas absorbance A can be calculated by the formula (1) using the methane gas signal value and the methane gas reference signal value measured by fine adjustment to around 7.63 μm by the second adjustment mechanism (S116). The gas concentration is calculated using the fact that the absorbance A and the gas partial pressure P (that is, the gas concentration) are in a proportional relationship. Finally, the atmosphere in the gas cell 80 is replaced with air (S118), and the expiration measurement is terminated.

  Even if the absorption peak wavelength is separated from 0.28 μm like acetone and methane, the wavelength can be quickly shifted by the first adjustment mechanism and the next measurement can be performed. For this reason, a plurality of gases to be measured can be measured in a short time. Further, since the wavelength can be finely adjusted in the vicinity of the absorption peak value by the second adjustment mechanism, the measurement accuracy can be increased.

FIG. 6 is a flowchart according to a first modified example of breath measurement.
In the modified example, the measurement order is changed from the flow chart of FIG. 4, exhalation is first blown into the gas cell 80 (S200), the gas signal value is measured (S204), and then replaced with the atmosphere (S208). The signal value may be measured (S212).

FIG. 7 is a flowchart according to the second modified example of the expiration measurement.
First, the breath diagnosis apparatus is turned on. Next, the gas cell 80 is evacuated and replaced with, for example, the atmosphere (S300).

  Subsequently, the wavelength of the quantum cascade laser 70 is roughly adjusted within the absorption spectrum of the first gas by the first adjustment mechanism (S302).

  Subsequently, the wavelength of the quantum cascade laser 70 is finely adjusted near the absorption peak value of the absorption spectrum of the first gas by the second adjustment mechanism, and then fixed. The detector 87 measures the transmission intensity (equal to the incident light intensity Io) of the infrared laser beam that has passed through the atmosphere, and sets it as the reference signal value (S304).

  Subsequently, exhalation is blown (S306), and the signal value of the first gas is measured (S308).

  Subsequently, the wavelength of the quantum cascade laser 70 is roughly adjusted within the absorption spectrum of the second gas by the first adjustment mechanism (S310).

  Subsequently, the wavelength of the quantum cascade laser 70 is scanned by the second adjustment mechanism in a range including the absorption peak value of the absorption spectrum of the second gas. The signal value of the second gas is measured in the peak region, and the reference signal value is measured in the base region (S312).

  The second modification is effective when the first gas is acetone or the like and the second gas is methane or the like having a narrower width than the absorption spectrum of acetone. That is, for methane having a narrow absorption spectrum, the reference signal value and the gas signal value can be measured in step S312 by scanning the wavelength range including the absorption peak, and the measurement flow can be simplified.

8A shows a first modification of the first adjustment mechanism, FIG. 8B shows a second modification thereof, and FIG. 8C shows a third modification thereof.
In FIG. 8A, the first adjustment mechanism is provided between the reflection mirror 92, the reflection mirror 92, and the quantum cascade laser 70, and changes the transmittance of the infrared laser light by rotation. It has an etalon 93 that changes the wavelength of the infrared laser light in accordance with the absorption spectrum of each gas.

  In FIG. 8B, the first adjustment mechanism is provided between the reflection mirror 92 and the reflection mirror 92 and the quantum cascade laser 70, and changes the incident angle of the infrared laser light by rotation or translation, It has the prism 94 which changes the wavelength of infrared laser light according to the absorption spectrum of each gas of several gas. 8A and 8B, a piezo element and a stepping motor for changing the distance between the reflection mirror 92 and the quantum cascade laser 70 may be further included.

  Furthermore, as illustrated in FIG. 8C, the first adjustment mechanism may include a plurality of bandpass filters 95 provided between the reflection mirror 92 and the quantum cascade laser 70 and having different bands. When the bandpass filter 95 is viewed along the line B-B, the bandpass filter 95 rotates around the optical axis 62 and one of the plurality of bandpass filters 65 can be selected.

FIG. 9A is a configuration diagram of the breath diagnosis apparatus according to the second embodiment, and FIG. 9B is a block diagram of the breath diagnosis apparatus according to the third embodiment.
As shown in FIG. 9A, the gas cell can be a hollow fiber 96. Further, an exhaust pump 97 can be provided in the gas cell. Further, as shown in FIG. 9B, if a mirror 85 that multi-reflects infrared laser light is provided inside the gas cell 80, multipath is achieved and sensitivity can be increased.

FIG. 10A is a schematic perspective view in which the quantum cascade laser is partially cut, and FIG. 10B is a schematic cross-sectional view taken along the line AA.
The quantum cascade laser includes at least a substrate 10, a stacked body 20 provided on the substrate 10, and a dielectric layer 40. In FIG. 1A, the first electrode 50, the second electrode 52, and the insulating film 42 are further provided.

  The stacked body 20 includes a first cladding layer 22, a first guide layer 23, an active layer 24, a second guide layer 25, and a second cladding layer 28. The refractive index of the first cladding layer 22 and the refractive index of the second cladding layer 28 are respectively lower than the refractive indexes of the first guide layer 23, the active layer 24, and the second guide layer 25, The infrared laser beam 60 is appropriately confined in the stacking direction of the active layer 24. The first guide layer 23 and the first cladding layer 22 can be collectively referred to as a cladding layer. The second guide layer 25 and the second cladding layer 28 can be collectively referred to as a cladding layer.

  The stacked body 20 has a stripe shape and can be called a ridge waveguide RG. If the two end surfaces of the ridge waveguide RG are mirror surfaces, the stimulated emission light is emitted from the light exit surface as infrared laser light 60. In this case, the optical axis 62 is defined as a line connecting the centers of the cross sections of the optical resonator having the mirror surface as the resonance surface. That is, the optical axis 62 coincides with the extending direction of the ridge waveguide RG.

  In a cross section perpendicular to the optical axis 62, if the width WA in the direction parallel to the first surface 24a and the second surface 24b of the active layer 24 is too wide, a high-order mode is generated in the horizontal horizontal direction, It becomes difficult to obtain an output. If the width WA of the active layer 24 is set to 5 to 20 μm, for example, the control in the horizontal transverse mode is facilitated. Assuming that the refractive index of the dielectric layer 40 is lower than the refractive index of any layer constituting the active layer 24, the dielectric layer 40 provided so as to sandwich the side surfaces 20a and 20b of the stacked body 20 causes the optical axis to be A ridge waveguide RG can be formed along the line 62.

FIG. 11A is a configuration diagram of the breath diagnosis apparatus according to the fourth embodiment, FIG. 11B is a schematic diagram in the vicinity of the external resonator, and FIG. 11C is a relative output with respect to the reflectance of the partial reflection coating film. It is a graph explaining the dependence of electric power.
The first adjustment mechanism is a diffraction grating 71a that intersects the optical axis 62 at a predetermined incident angle γ and can be translated in one or two dimensions in the XY plane. The diffraction grating 71a can be translated by a stepping motor 99 and a controller 98 that controls the stepping motor 99. The diffraction grating 71a and the partially reflective coating film PR (reflectance: R2) of the quantum cascade laser 70 constitute an external resonator (EC). Infrared laser light emitted from the partially reflective coating film PR enters the gas cell 80 along the optical axis 62.

12A and 12B are schematic plan views of a diffraction grating.
In FIG. 12A, the diffraction grating 71a has a plurality of regions having different pitches along the X direction. The resonance wavelength is region B> region A> region C, and the wavelength can be roughly adjusted by moving in the X direction. In FIG. 12B, the resonance wavelength is region E> region F> region H> region D. For example, the wavelength can be roughly adjusted by moving along the broken line direction SD. The cross-sectional shape of the diffraction grating 71a may be asymmetric.

  As the reflectance R2 of the partial reflection coating film PR is higher, the number of light reciprocations in the resonator is increased, so that the wavelength controllability is improved and stabilized.

On the other hand, as shown in FIG. 11 (c), the light output Pout becomes maximum at the reflectance Rp between the reflectance R2 of zero and 100%, and the reflectance R2 increases when Rp ≦ R <100%. Decreases with. That is, it is more preferable to set the reflectance R2 to, for example, Rp or more and the reflectance R _{−3 dB} or less at which the optical output is reduced by 3 dB because the optical output can be maintained while keeping the line width stable.

FIG. 13 is a band diagram for explaining the operation of the quantum cascade laser.
The active layer 24 has a cascade structure in which the first regions 25 and the second regions 26 are alternately stacked. The first region 25 can emit infrared laser light 60 having a wavelength of, for example, 3 μm or more and 18 μm or less by the intersubband optical transition of the quantum well layer 72. Further, the second region 26 can relax the energy of carriers (for example, electrons) E injected from the first region 25.

  In the quantum well layer 72, when the well width WT is reduced to, for example, several nanometers or less, the energy levels become discrete, and the subband 72a (high level Lu) and the subband 72b (low level Ll). , Etc. The electrons E injected from the injection barrier layer 73 can be effectively confined in the quantum well layer 72. When carriers transition from the high level Lu to the low level Ll, light (hn) corresponding to the energy difference (Lu−Ll) is emitted (optical transition). The quantum well layer 72 may have a plurality of wells with overlapping wave functions, and may have common levels Lu and Ll.

  Intersubband transitions occur in either the conduction band or the valence band. That is, recombination of holes and electrons by a pn junction is not necessary, and light is emitted by optical transition of only one of the carriers. In the case of this figure, the stacked body 20 injects electrons E into the quantum well layer 72 through the injection barrier layer 73 by the voltage applied between the first electrode 50 and the second electrode 52, Interband transition occurs.

  The second region 26 has a plurality of subbands (also referred to as minibands). The energy difference in the subband is preferably small and close to the continuous energy band. As a result, the energy of electrons is relaxed, so that the second region 26 does not generate infrared laser light having a wavelength of 3 to 18 μm. The electrons of the low level Ll in the first region 25 pass through the extraction barrier layer 74, are injected into the second region 26, are relaxed, and are injected into the first region 25 of the next stage cascaded (electrons). E) The next optical transition occurs. That is, in the cascade structure, since the electrons E perform optical transitions in the unit structure 27, it is easy to extract a high light output from the entire active layer 24.

The quantum well layer 72 may include GaAs, and the barrier layer may include Al _x Ga _1-x As (0 <x <1). In this case, when the substrate 10 is made of GaAs, the lattice matching with the quantum well layer and the barrier layer can be improved. The first cladding layer 22 and the second cladding layer 28 have an n-type impurity concentration of, for example, 6 × 10 ¹⁸ cm ⁻³ by Si doping, and can have a thickness of, for example, 1 μm. The first guide layer 23 and the second guide layer 25 have an n-type impurity concentration of, for example, 4 × 10 ¹⁶ cm ⁻³ and can have a thickness of 3.5 μm by Si doping. Further, the width WA of the active layer 24 can be 14 μm, and the length L of the ridge waveguide RG can be 3 mm. The quantum cascade laser can operate, for example, at an operating voltage of 10 V or less, and the current consumption is lower than that of a carbon dioxide laser device or the like, so that the power consumption can be reduced.

  According to the 1st-4th embodiment, the density | concentration of the some gas contained in exhalation can be measured using the infrared laser beam which has a wavelength range of 3-12 micrometers. These breath diagnosis devices, such as human breath BR, contain nitrogen, oxygen, carbon dioxide, water, etc. as the main components, and can measure changes in temperature such as molecular absorption peaks and light source wavelengths. Even in the atmosphere, the wavelength of the infrared laser can be accurately adjusted to the absorption peak of the molecule to be measured. In addition, it is possible to reduce the size and power consumption compared with a device that uses a carbon dioxide laser device, a Raman laser device, or the like as a light source of infrared laser light. Further, the concentration of the plurality of gases can be calculated quickly and accurately by coarsely adjusting the wavelength of the quantum cascade laser with the first adjusting mechanism and then finely adjusting the wavelength with the second adjusting mechanism.

  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.

  62 optical axis, 70 quantum cascade laser, 71, 71a diffraction grating, 80 gas cell (housing), 81 exhalation inlet, 82 exhalation outlet, 83 entrance window, 84 exit window, 85 multiple reflection mirrors, 87 detector, 88 Signal processing unit, 90 Peltier element, 91 light source unit, 92 reflecting mirror, 93 etalon, 94 prism, 95 bandpass filter, γ predetermined incident angle

Claims (13)

An exhalation diagnostic apparatus capable of measuring concentrations of a plurality of types of gases contained in exhaled breath,
A quantum cascade laser having one end face provided with a reflective coating film and emitting infrared light by intersubband transition of electrons in a plurality of quantum wells;
Shift in the absorption spectrum of one type of gas one type of the first adjustment mechanism shifts in the absorption spectrum of the gas, and the wavelength of the infrared light of the gas the plurality of types of wavelengths of the infrared light A wavelength controller having a second adjustment mechanism;
And expiration suction port, and expiration outlet, and the entrance window of the infrared light, a housing having an a exit window, which is emitted as transmitted light without being absorbed by the exhalation of the infrared light,
A detection unit for detecting the intensity of the front infrared light;
A signal processing unit that calculates the concentration of the plurality of types of gases from the intensity of incident light to the incident window and the intensity of the transmitted light ;
Equipped with a,
The reflectance of the reflective coating film when the light output of the transmitted light reaches the maximum value is represented by Rp, and the light output of the transmitted light is reduced to one half of the maximum value as the reflectance increases. The breath diagnosis apparatus , wherein the reflectance of the reflective coating film is Rp or more and R _{-3 dB} or less in the wavelength range of the infrared light when the reflectance when decreasing is expressed as R _{-3 dB} . The first wavelength adjusting mechanism includes a reflection mirror and an etalon disposed between the reflection mirror and the quantum cascade laser, and changes an incident angle of the infrared light by rotating the etalon. The breath diagnosis apparatus according to claim 1, wherein the infrared light transmittance is changed. The first wavelength adjustment mechanism includes a reflection mirror and a prism disposed between the reflection mirror and the quantum cascade laser, and changes the incident angle of the infrared light by rotating the prism. Item 2. The breath diagnosis apparatus according to Item 1. The first wavelength adjusting mechanism has a reflection mirror and a prism disposed between the reflection mirror and the quantum cascade laser, and translates the prism to move between the quantum cascade laser and the reflection mirror. The breath diagnosis apparatus according to claim 1, wherein the distance is changed. The breath diagnosis apparatus according to any one of claims 2 to 4, wherein a distance between the reflection mirror and the quantum cascade laser changes. Wherein the first wavelength adjustment mechanism includes a reflecting mirror, it said provided between the reflecting mirror and the quantum cascade laser, possess a plurality of band pass filters having different bands, and the red for the plurality of band-pass filter The breath diagnosis apparatus according to claim 1 , wherein the irradiation position of the external light is changed . The breath diagnosis apparatus according to claim 1, wherein the first wavelength adjustment mechanism includes a diffraction grating, and changes an incident angle of the infrared light by rotating the diffraction grating. The first wavelength adjusting mechanism includes a diffraction grating,
The breath diagnosis apparatus according to claim 1, wherein the diffraction grating is rotated around the optical axis of the infrared light to irradiate a grating region having a different pitch . Wherein the first wavelength adjustment mechanism includes a diffraction grating, breath diagnosis device of one-dimensional or two-dimensionally movable claim 1, wherein said diffraction grating. The breath diagnosis apparatus according to any one of claims 1 to 9, wherein a non-reflective coating film is provided on the other end face of the quantum cascade laser. The breath diagnosis apparatus according to any one of claims 1 to 10 , wherein the second adjustment mechanism changes an operating current value or a duty of the quantum cascade laser . The breath diagnosis apparatus according to claim 1 , wherein the second adjustment mechanism includes a Peltier element that changes an operating temperature of the quantum cascade laser . Wherein the housing, breath diagnostic apparatus according to any one of claims 1 to 12, further comprising a multiple reflection mirror to be emitted from the exit window After multiple reflections the infrared light incident on the entrance window.

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