JPH04152247A - Infrared ray spectrometer - Google Patents

Abstract

PURPOSE:To construct an analyzer in a small size and have a high certainty and high sensitivity analysis by furnishing a super-small light source which emits infrared rays into each cell, and providing a light chopper which shuts off intermittently the infrared rays after passing the cells. CONSTITUTION:A beam of light emitted from a super-small lamp 41 passes through infrared penetration films 42, 43, and only infrared rays are incident on a standard cell 30 and a measuring cell 31. The infrared rays projected on these cells 30, 31 are reflected by mirrors 44, 45, passed through the standard gas and the gas to be measured, respectively, led to filters 46, 47 by the mirrors 44, 45, and shut off and allowed to proceed by a light chopper 48. The beam of light having passed this chopper 48 is sensed by an infrared sensor 49, and a signal processing circuit 50 calculates the concentration of the gas measured on the basis of the difference in the penetration photo amount between the standard cell 30 and measuring cell 31. Thus analyzer is constructed small, and high sensitivity and high certainty analyses are made practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> This invention relates to miniaturization of an analyzer using infrared rays.

<Prior Art> FIG. 5 is a diagram illustrating the principle of a conventional infrared analyzer that measures the concentration of a measurement gas from the difference in the amount of infrared rays absorbed by a standard scum and a measurement scum. The light emitted from the infrared light source 1 is made into intermittent light by an optical sector 3 rotated by a synchronous motor 2, and then divided into two beams by a distribution cell 4, which enter a standard cell 5 and a measurement cell 6, respectively. The standard cell 5 is normally filled with an inert gas (N2, etc.) as a g-heavy gas, and the incident infrared rays are not characteristically absorbed in this cell.

On the other hand, in the measurement cell 6, light is absorbed in a specific wavelength band depending on the components and concentrations in the measurement gas. By detecting the difference in intensity between these two luminous fluxes, the concentration of the measurement gas component can be measured. The gas-filled detector 7 consists of a chamber filled with gas to be measured at a constant concentration and a micro flow sensor 8 connected to the chamber. Only light at the gas's characteristic absorption wavelength is absorbed, causing the gas in the sealed room to expand intermittently. The magnitude of the expansion force depends on the amount of light in the characteristic wavelength range of the measurement waste component that enters the room.

In this case, the pressure difference between the two chambers is detected by the microflow sensor 8 as a change in gas flow rate. The electrical output of the micro flow sensor 8 is amplified by an amplifier 9, then synchronously rectified by a synchronous rectifier circuit 10 in synchronization with the rotation period of the rotating sector 3, and then passed through a smoothing circuit 11. A concentration signal is output via a DC amplification circuit FI@12.

<Problem to be solved by the invention> However, the device with the above configuration consists of multiple mechanical parts and electric circuits, and the whole constitutes one system, so although it is highly sensitive, it cannot be used as an element-sized gas sensor etc. The drawback is that it is very large in size and requires a large amount of sample gas for measurement. On the other hand, element-sized gas sensors and the like have a problem of extremely poor accuracy and sensitivity.

<Object of the Invention> The present invention was made to solve the above-mentioned problems, and its purpose is to realize an infrared analyzer with high accuracy, high sensitivity, and an element size.

Means for Solving the Problems> The present invention relates to an infrared analyzer that measures the concentration of a measurement gas from the difference in the amount of infrared rays absorbed by a standard gas and measurement waste. A standard cell, a measurement cell through which the measurement gas flows, a microvalve through which each of the gases is introduced into or discharged from these cells, an ultra-compact light source that emits infrared rays into each of the cells, and an infrared ray that passes through each of the cells. An intermittent optical chopper and an ultra-compact infrared sensor that detects infrared light transmitted through the optical chopper are formed on a substrate using microfabrication technology.

Effect〉 Ultra-small measurement cell is used, so it is very small! Since the concentration can be measured using the measurement gas and the detection is performed using an ultra-compact infrared sensor, the measurement can be performed with high sensitivity and accuracy.

<Example> Figure 1 is an exploded perspective view showing an infrared analyzer according to the present invention.9 The measurement principle of this device is the same as in Figure 5.
The concentration of the measured gas is measured from the difference in the amount of infrared absorption between the standard gas and the measured gas.

In the figure, 21 is an upper silicon substrate, 22 is an intermediate glass substrate, and 23 is a lower silicon substrate. Substrate 21~
23 form a sandwich structure and are very firmly adhered to each other by electrostatic bonding, so that the gas flowing inside does not leak to the outside. 24 and 25 are formed on the substrate 21, and are sampling microvalves for introducing standard gas and measurement gas into the cell, respectively;
6゜27 is a valve actuator that drives each of these micro valves 24 and 25, and 28 and 29 is a substrate 2.
2, through holes through which the standard gas and measurement gas pass downward in the figure; 30. 31 are standard cells and measurement cells, respectively, formed on the substrate 23 by anisotropic etching of silicon; 32.33; 34 and 35 are through holes formed on the substrate 22 to filter the standard gas and measurement gas upward in the figure, and microvalves 34 and 35 are formed on the substrate 21 to discharge the standard gas and measurement gas from the cell, respectively. , 36.37 are these microvalves 34.35
These are valve actuators that drive the respective valves.

41 is an ultra-compact lamp (micro lamp) that emits light containing infrared rays; 42.43 is an infrared transmitting film that transmits only infrared rays out of the light emitted from the ultra-compact lamp 41;
4.45 are standard cells 30. High-precision mirrors are formed by vapor-depositing gold or the like on the inner wall of the measurement cell 31, and 46 and 47 are mirrors 44 and 45 that reflect the light that has passed through the infrared transmitting films 42 and 43, respectively. wavelength selection filters into which each reflected infrared light enters;
48 is a rotating ultra-small optical chopper (micro chopper) that periodically interrupts the light that has passed through the filters 46 and 47, and is moved by electrostatic force, etc.; 49 is a pyroelectric device that detects the infrared rays that have passed through the optical chopper 48; An ultra-small infrared sensor 50 such as a type or Hg Cd Te is formed on the substrate 21 and is a signal processing circuit that converts an output signal from the infrared sensor 49 into measurement data.

Each of the above-mentioned components is formed on each substrate using a machine string processing technique for IC manufacturing or a micro-processing technique similar thereto.

The operation of the apparatus having the above configuration will be explained next with reference to FIGS. 2 and 3. Note that the same parts as in FIG. 1 are given the same symbols. The light emitted from the micro lamp 41 passes through the infrared transmitting films 42 and 43, so that only the infrared rays are transmitted to the standard cells 30 and 30, respectively. The light enters the measurement cell 31. Standard cell 3
0. Infrared light 62.63 incident on the measurement cell 31 is reflected by mirrors 44.45, passes through the standard gas and measurement gas, and is guided again by the mirrors 44.45 to filters 46.47, and is then passed through the optical chopper. Intermittent at 48. The light that has passed through the optical chopper 48 is detected by an infrared sensor 49, and the concentration of the measurement gas is calculated in a signal processing circuit 50 based on the difference in the amount of transmitted light between the standard cell 30 and the measurement cell 31. In FIG. 2, 61 is a seal ring used together with the micro valve 25. In FIG. 3, 81 is the drawer $[i
It is.

Figure 4 shows the micro lamp 4 shown in Figures 1 and 2.
FIG. 1 is a cross-sectional view of a main part configuration showing details of FIG.

Note that the same parts as in FIGS. 1 and 2 are given the same symbols, and the explanation will be omitted. 72 is a vacuum chamber formed by micromachining technology near one surface of the substrate 21 (hereinafter referred to as the lamp forming surface), and 73 is a vacuum chamber supported by the substrate 21 in the form of a double-sided beam inside the vacuum chamber 72. a filament formed and coated with an infrared emitter, 74 is the substrate 2;
1 on the lamp forming surface and the structure 77 (f
The reflective heat dissipating film 75 formed to cover the substrate 21 is adjacent to the vacuum chamber 72 and consists of a portion processed to have a smaller thickness on the other surface (hereinafter referred to as the light emitting surface) of the substrate 21. A light emitting section 76 is a light emitting section 7 on the light emitting surface of the substrate 21.
A reflective film 77 is formed around the vacuum chamber 72, and a reflective heat dissipating film 74 is a structural part that covers the top of the vacuum chamber 72 to seal it.
and reflection I! ! ! As 76, a metal film such as Au can be used.

An example of the left and right lengths of the substrates 21 to 23 in FIG. 1 may be, for example, 10 mm.

The operation of the apparatus having the above configuration will be explained next. filament 7
The light emitted upward in FIG. 4 due to the light emission of No. 3 is reflected downward by the reflective heat dissipation film 74, and is emitted to the outside from the light emitting portion 75 together with the light emitted directly downward from the filament 73. In the light emitting part 75, since the substrate 21 is thin, absorption and attenuation of light is small.
Since the light obliquely emitted from the light emitting portion 75 and the reflected light from the components on the lower side of the figure are reflected without entering the substrate 21, efficiency can be improved.

In addition, when the temperature of the substrate 21 rises due to a portion of the light radiated upward in the figure being absorbed by the substrate 21 and heat conduction from the filament 73, this heat is transferred to the reflective heat dissipation film 7.
4, heat is dissipated with high efficiency, so the temperature rise of the substrate 21 can be suppressed. In order to reduce light absorption, the structure 77 that seals the vacuum chamber 72 is also formed with a small thickness.

Further, by forming the light emitting portion on the opposite side to the lamp forming surface, there is no convex portion on the light emitting surface, so it is easy to form a structure for utilizing the emitted light. Here, in the micro lamp 41, since silicon is used as the substrate, there is absorption at a wavelength of light of 1.1 μm or less.
Since it transmits at wavelengths longer than that, it can be used as is to form an infrared lamp. In addition to silicon,
By forming an arbitrary ceramic in the light emitting portion, an infrared lamp that efficiently emits infrared light can be constructed.

Furthermore, in FIG. 4, a concave portion is formed on the light emitting surface of the substrate 21 using micro processing technology to reduce the thickness of the light emitting portion 75, but if the entire substrate 21 is made thinner, this processing becomes unnecessary. Become.

According to an infrared analyzer with this configuration, by integrating and miniaturizing sensors that have low accuracy and sensitivity on their own like an IC, an ultra-compact, high-performance infrared analyzer with high sensitivity and high accuracy can be realized. can do. That is, for example, when a pyroelectric sensor is used as the infrared sensor 49, it is ultra-small and has a small heat capacity, and even a small amount of light can easily raise the temperature, resulting in improved sensitivity. In addition, since it uses an ultra-small measurement cell, the amount of sample gas to be measured can be miniscule.As a result, it is a revolutionary product that is smaller in size than conventional gas sensors but has sensitivity and accuracy equal to or higher than conventional infrared analyzers. It is possible to realize a unique infrared analyzer.

In addition, mass production and cost reduction can be achieved by integrating the sensor components into small sensor components using microfabrication technology used in IC manufacturing.

In the above embodiments, the optical chopper 48 is not limited to one using a piezoelectric actuator or an electrostatic actuator, but may be an optical one such as an electro-optical element.

Further, as the l1li quasi-dregs, any inert dregs that does not absorb infrared rays, such as N2, can be used.

Also, by selecting filters 46 and 47, 1 μm
Absorption at any wavelength between ~10 μm can be used for measurements.

Further, the microlamp 41 is not limited to the configuration shown in FIG. 4, but any light source that emits light including infrared rays and can be realized using microprocessing technology can be used.

Alternatively, thermal expansion may be detected in a conventional manner using a pressure sensor or the like formed by micro-processing technology as an infrared sensor.

Further, by creating a structure in which the optical path in the cell is multiple-reflected by a reflective film, the amount of infrared absorption can be increased and the SZN ratio can be improved.

Furthermore, by forming a plurality of measurement cells on the same substrate and incorporating different wavelength filters and optical sensors into each measurement cell, multi-component analysis like gas chromatography can be performed in real time.

<Effects of the Invention> As described above, according to the present invention, with high accuracy and sensitivity,
It is possible to realize an element-sized infrared analyzer.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the infrared analyzer according to the present invention, FIGS. 2 and 3 are sectional views showing the main parts of the apparatus shown in FIG. 1, and FIG. FIG. 5 is a sectional view showing the details of the main part of the microlamp 41 in FIG. 2 and FIG. 2, and FIG. 21.22.23...Substrate, 24.25.34°5.
...Micro valve, 30...Standard cell, 1...Measuring cell, 1...Ultra small light source, 48...Hikari chotsuba--1/

Claims (1)

[Scope of Claim] An infrared analyzer that measures the concentration of a measurement gas from the difference in the amount of infrared absorption between the standard gas and the measurement gas, comprising: a standard cell through which the standard gas flows, a measurement cell through which the measurement gas flows, and these cells. a microvalve that introduces or discharges each of the gases, an ultra-small light source that emits infrared rays into each of the cells, an optical chopper that cuts off the infrared rays that have passed through each of the cells, and a detection of the infrared rays that have passed through the optical chopper. An infrared analyzer characterized in that an ultra-compact infrared sensor is formed on a substrate using micro-processing technology.