JPH0650263B2 - Infrared spectrophotometer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared spectroscopic measurement device for measuring the concentration distribution of gas molecules in the atmosphere.

Structure of Conventional Example and Problems Thereof In general, the basic principle of the infrared spectroscopic measurement device is that a light emitted from a light source is formed into a parallel light beam by a collimator mirror by forming an image of light in an entrance slit through a sample to be measured by a concave mirror. The parallel rays are reflected by a plane mirror to be dispersed light by a prism, and an image of its spectrum is formed on the exit slit by a concave mirror. From the exit slit, a mirror or prism is rotated so that only light of a certain wavelength is extracted and detected by an infrared detector. In order to further increase resolution and dispersive power, dispersed light is measured using a diffraction grating other than a prism, a multi-path spectroscope that uses light that has passed through the prism several times, or a light beam is divided into two and one is measured. The other one is used as a sample, and the empty sample is put into a spectroscope alternately at a certain frequency by using a rotating mirror, and the mechanical ratio method or both 90 ° of light is obtained by comparing the intensities of the signals generated at the detector at that frequency. There is an electrical ratioing method in a phase shifted spectrometer. These spectroscopic measurement devices have high resolution, high dispersion and good performance, but have the drawback that only one spectral line can be measured at a time from the exit slit. Moreover, the device is large and its structure is complicated.

Moreover, the quantum type and the thermal type are used for the detectors used in these measuring devices. Although the quantum type has high sensitivity, it has a limited measurement wavelength and requires cooling, which makes the device large. A thermocouple is typically a thermocouple or a pyroelectric type. These have lower sensitivity than the quantum type, but they are often used because they can cover a wide wavelength range and can operate at room temperature. Thermocouples have the drawback of having a long time constant, but pyroelectric type is an induction of surface charge caused by heat absorption of incident infrared rays.
Since the response is relatively fast, fast measurement is possible. The pyroelectric type needs to interrupt the incident infrared rays, and the output signal depends on this interrupt frequency. When the intermittent frequency is fast, the influence of lateral heat diffusion of the device and heat conduction of the substrate is small, but the output signal decreases. Therefore, it is effective for sufficiently large infrared energy, but it is a problem when detecting low-energy infrared light at a low intermittent frequency.

It is an object of the present invention to solve the above problems and to provide an infrared spectroscopic measurement device capable of simultaneously measuring the spectrum of a wide range of low-energy infrared light in parallel. .

Configuration of the Invention Since the configuration of the present invention simultaneously measures a wide spectrum of low-level infrared energy in parallel, a device for interrupting infrared rays of less than 30 Hz and a spectroscope for obtaining a dispersive spectrum of the interrupted infrared rays, A plurality of solid pyroelectric material elements separated from each other for simultaneously detecting a wide range of low-energy infrared spectra obtained by this spectrograph were held in the support substrate only at both ends of the element and floated in the air. A hybrid type detector in which an element portion configured in a bridge shape and a plurality of amplifiers corresponding to the solid pyroelectric element are integrated, a device for phase-detecting and amplifying positive and negative signals from the detector, and It is composed of a device for simultaneously reading signals in parallel, a device for converting analog to digital, and a storage device.

Description of Embodiments FIG. 1 is a schematic view of an embodiment of a measurement system of an infrared spectroscopic measurement device of the present invention.

The infrared radiant light 3 emitted from the infrared radiant light source 1 passes through the sample 103 to be measured and is a lens 2 which is transparent to infrared light.
An image of the light is formed at the entrance slit of the spectroscope 7. This image of light is a transmission component and an absorption component of light when passing through the measured sample 103. Reference numeral 102 denotes an infrared filter, which determines the region of the measured infrared spectrum. The image of the light formed in the entrance slit of the spectroscope 7 passes through the collimator mirror of the spectroscope and is converted into the infrared dispersed light 20 by the diffraction grating, and the detector 8 is provided with a plurality of individual solid-state pyroelectric element arrays. 9 is imaged. Since the solid pyroelectric element utilizes a surface charge change phenomenon of temperature change caused by infrared absorption, the light imaged on the solid pyroelectric element array 9 must be interrupted at appropriate timing. This interruption is performed by rotating a chopper disc 4 having several holes of appropriate size. Reference numeral 5 is a motor for rotating the chopper disc 4, and 6 is a chopper control drive device for controlling and driving the rotation of the motor 5. The output signal of the solid pyroelectric element by infrared light obtained by the interruption of the chopper disk 4 is an alternating current signal having positive and negative polarities, and has an infrared intermittent frequency characteristic. The frequency characteristic of the output signal is inversely proportional to the intermittent frequency _O when the intermittent frequency ( _{O 2} ) is faster than the frequency determined by the smaller of the thermal time constant and the electrical time constant. Therefore, if the intermittent frequency becomes lower in the frequency range higher than _O , the noise will However, the output signal increases by 1 /.

FIG. 2 shows a specific structure of the infrared detector 8, and the same parts as those in FIG. 1 are designated by the same reference numerals. Reference numeral 16 is an insulating substrate having a small thermal conductivity, which is a supporting substrate for forming the solid pyroelectric element 18 in a bridge shape. In the solid pyroelectric element 18, an absorption electrode 17 made of nickel, chromium, gold or the like is formed on the infrared absorption surface side of the pyroelectric material by vapor deposition, sputtering or the like. Reference numeral 19 denotes a common electrode on the back surface, which is a metal electrode having a high reflectance such as gold or aluminum for the purpose of reflecting infrared rays transmitted from the solid pyroelectric element 18 and reabsorbing them by the solid pyroelectric element 18 to improve efficiency. The pyroelectric element 18 is fixed on the support substrate 16 with an insulating adhesive 21 and a conductive adhesive 22. The multiple array ratio of the pyroelectric elements 18 is divided by dicing or the like at a pitch according to a desired purpose after fixing and adhering one sheet of the pyroelectric element wafer, and a plurality of individual solid pyroelectric elements can be arranged independently of each other. . Reference numeral 10 is an amplifier that amplifies the signal generated by infrared radiation from the solid pyroelectric element array 9, and is connected to the pyroelectric element directly or indirectly by wire bonding or the like.
Reference numeral 15 is a window for transmitting infrared rays, which has a hybrid structure in which the window 15, a plurality of solid-state pyroelectric element arrays 9 arranged in a large number, and an amplifier 10 are contained in one package. The feature of this hybrid structure is that it has a terminal capable of appropriately adjusting the band adjustment externally by adjusting the electric constant. By having such a feature, it can be easily adjusted according to the type of the incident spectrum and the versatility is enhanced.

Since one of the objects of the present invention is to detect infrared rays of low energy level, the interrupt frequency is adapted to less than 30 Hz. The deterioration of the output signal due to the low frequency is greatly influenced by the lateral thermal diffusion of the element itself and the thermal conduction of the substrate, so that the pyroelectric elements adjacent to each other are completely separated from each other to prevent the lateral thermal diffusion. In addition, the loss due to heat conduction of the substrates is improved by forming the pyroelectric element in a bridge shape with the pair of supporting substrates as pillars. Still another object of the present invention is to
It is to measure infrared dispersed light in a wide wavelength region in parallel at the same time. For this purpose, the detector has a structure in which a large number of a pair of support substrates are arranged on a pillar, which are separated from each other and independent of each other.

Returning to FIG. 1 again, the positive and negative signals from the detectors 8 obtained by amplifying the signals generated in the respective pyroelectric elements by the intermittent radiation of the infrared dispersed light 20 by the respective amplifiers 10 are It is applied to the detector amplifier 11. The signal given to the phase detection amplifier 11 is a tuning amplifier, and after being band-combined to some extent, a switch is operated by the reference signal of the chopper control driving device 6 to perform phase detection, and an output signal is given to an integrating circuit to obtain a DC signal. obtain. By passing through the amplifier 11, it is possible to detect only a signal having the same frequency as the reference signal for interrupting the incident infrared rays and a phase having a constant relationship, and to extract a signal having a good S / N with the noise component eliminated as much as possible. . The output signals of the phase detection amplifier 11 are simultaneously given in parallel to the multiplexer 12. Multiplexer 12
The signals given to the
It is given to the digital converter 13 and converted into a digital signal. The digitally converted signal is stored in the storage device 14 and given to an appropriate utilization device 104 at a necessary timing.

EFFECTS OF THE INVENTION As described above, according to the present invention, the infrared light is intermittently incident at a frequency of less than 30 Hz, and the spectroscopic device that disperses the infrared light and the dispersed infrared light from the spectroscopic device are separated from each other and the both ends are bridged. Infrared spectroscopic measurement device equipped with multiple solid pyroelectric elements supported in a circular pattern and detecting positive and negative signals generated in the solid pyroelectric elements simultaneously in parallel. Can be simultaneously measured in parallel over a wide area.
This is a great advantage that a large amount of infrared spectrum information can be quickly measured at a time by a phenomenon that changes from moment to moment. In addition, the infrared detector has a hybrid configuration in which a large number of solid pyroelectric elements, which are separated and independent, and an amplifier are housed in one package, and also has a terminal capable of externally adjusting the band, which facilitates adjustment. It has the feature that it exists.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of the infrared spectroscopic measurement device of the present invention, and FIG. 2 is an enlarged perspective view of the detector portion of the infrared spectroscopic measurement device of FIG. 1 ... Light source, 2 ... Lens, 3 ... Infrared radiation, 4 ...
… Chipper disk, 5 …… Motor, 6 …… Chipper control drive device, 7 …… Infrared spectroscope, 8 …… Detector, 9 …… Solid pyroelectric element array, 10 …… Amplifier, 11 …… Phase Detection amplifier, 12 ... Multiplexer, 13 ... Analog-digital converter, 14 ... Storage device, 15 ... Infrared transmission window,
16 ... Insulating support substrate, 17 ... Infrared absorbing electrode, 18 ...
... Solid pyroelectric element, 19 ... Common electrode on the back surface, 20 ... Infrared dispersed light, 21 ... Insulating adhesive, 22 ... Conductive adhesive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeo Ishigaki, 3-10-1, Higashisanda, Tama-ku, Kawasaki-shi, Kanagawa Matsushita Giken Co., Ltd. (72) Akio Teranishi 3-chome, Higashimita, Tama-ku, Kawasaki-shi, Kanagawa No. 10-1 in Matsushita Giken Co., Ltd. (72) Inventor Kunio Nakamura 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Matsushita Giken Co., Ltd. (56) Reference JP-A-50-50982 (JP, A) ) JP-A-52-42782 (JP, A) JP-A-53-36285 (JP, A) JP-A-56-57925 (JP, A) JP-A-56-79923 (JP, A) JP-A-57- 120830 (JP, A) Actual development Sho 57-63235 (JP, U) Special public Sho 50-19064 (JP, B1) Special public 46-1640 (JP, B1) Special public Sho 56-51291 (JP, B2)

Claims (1)

[Claims] 1. A chopper device for interrupting incident infrared light,
A spectroscopic device that disperses intermittent incident infrared light, a solid-state pyroelectric element that detects spectroscopic infrared light from the spectroscopic device and is separated from each other and arranged in a large number in a row, and the solid-state pyroelectric device. A positive and negative signal generated in the phase detection amplifier for phase detection in synchronism with the chopper signal of the chopper device, and the output signal from the phase detection amplifier is simultaneously and in parallel for each of the plurality of arranged solid pyroelectric elements. An infrared spectroscopic measurement device comprising a reading device, wherein the intermittent period of the chopper device is less than 30 Hz.