JP2007298489A - Infrared detection device using thermal stress wave focusing phenomenon, thermal stress wave focusing device, and infrared detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal type sensor that can be applied to a large wave length range, has high response speed, and has a large operation temperature region. <P>SOLUTION: An infrared detection device employing a thermal stress wave focusing phenomenon is a kind of thermal type sensors. A general thermal type sensor uses a method of utilizing the temperature increase of the sensor, but the present thermal type sensor focuses the thermal elastic wave momentarily excited by shocking thermal expansion by absorbed heat quantity of incoming infrared radiation, converts it into an electric signal, and measures it. Therefore, the present thermal type sensor has a response speed about 1000 times that of a sensor utilizing the temperature increase, and can be operated even at the applied temperature region of 1000°C or higher, and the structure is extremely simple. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Detailed Description of the Invention

  The present invention can withstand a severe heat load of 1000 ° C. or more with a short response time of 5 μsec or less, and hold it with only one type of detector, such as an infrared laser in a wide wavelength range of about 0.7 μm to 300 μm. The present invention relates to an infrared detection apparatus and method for detecting energy intensity.

  Conventionally, when the principle of an infrared detection sensor such as an infrared laser is roughly classified, a quantum sensor using photo-electric conversion and a thermal sensor using photo-thermal conversion are known. Quantum sensors use the photovoltaic effect, thermal conduction effect, and photoemission, and thermal sensors are well known that use the change in conductivity, pyroelectric effect, and thermoelectric effect. Yes.

  What governs the performance of an infrared sensor that detects an infrared laser or the like is the applicable wavelength range, response time, and operating temperature range of the sensor. Many quantum sensors have a fast response but a narrow application wavelength range, and the operating temperature is destroyed when the sensor temperature rises too rapidly, so it absorbs only part of the power of medium and high power infrared lasers. It can be operated or cooled.

  In the application temperature range, quantum sensors are generally low in temperature to generate electrons, and few are operated at high temperatures above room temperature. Moreover, since the thermal sensor itself is at a high temperature in a high temperature state, it is impossible to instantaneously measure the amount of heat of infrared rays such as a laser.

  For a sensor that detects response using heat absorption, such as a thermal sensor, a method of transmitting heat to a resistor or thermocouple to convert it into an electrical signal is well known, but the response is very slow and is on the order of sec. Even a fast one is in the order of mmsec, and it has been said that this detection method cannot provide a response speed of the quantum sensor.

Problems the invention is trying to solve

  As described above, it is an urgent issue to develop a thermal sensor that can be applied to a wide wavelength range, which is a characteristic of a thermal sensor, has a quick response, and has a wide operating temperature range.

Means for solving the problem

  In order to achieve the above object, the infrared detection device using the thermal stress wave focusing phenomenon of the present invention is a kind of thermal sensor, but a method in which a general thermal sensor uses the temperature rise of the sensor. On the other hand, the thermal sensor that uses the temperature rise is measured because the thermoelastic wave that is instantaneously excited by the shock thermal expansion due to the amount of heat of the absorbed infrared rays is focused and converted into an electrical signal. Compared to the above, the response is about 1000 times faster, the application temperature region can be operated even at 1000 ° C. or more, and the structure is very simple.

Action

  According to such an infrared detection device and detection method, the sphere is proportional to the amount of infrared light absorbed by the light receiving unit exposed so as to receive all output of infrared light including intermittently excited medium power or high power laser. Due to the heat absorption of the surface, a spherical thermoelastic wave is instantaneously generated, which is focused on the center of the sphere to generate a large elastic wave. Since the elastic wave is composed of a longitudinal wave and a transverse wave, if the acoustic wave is selected as a longitudinal wave by a liquid viscous grease layer passing process and converted into an electrical signal by a piezoelectric element and measured, the intensity of the irradiated infrared rays is increased. Is measured accurately. This thermoelastic wave is excited by an instantaneous temperature change, and its propagation speed has a speed of sound, and it operates if the applied temperature has a temperature difference from the environmental temperature, so that it operates even if the measurement environment is high. It has characteristics. For this reason, the application temperature range is wide and the response can be accelerated to μsec or less.

  Embodiments of the present invention will be described in detail below with reference to the drawings of FIGS.

  An embodiment of an infrared detector using the thermal stress wave focusing phenomenon of the present invention will be described with reference to FIG. In FIG. 5, the infrared laser oscillator is a DCR-11Q switch Nd: YAG laser (18) manufactured by Spectra-Physics, and uses a second harmonic (532 nm). The emitted laser is reflected by a mirror (19) and focused by a convex lens (20) having a focal length of 200 mm. The light beam that has passed through the convex lens is branched in two directions by the spectroscopic plate (21). One is input to the JE-05 calorimeter (23) manufactured by Spectron after passing through the ND filter (22) for measuring the amount of input laser energy, and the output information is a change in voltage as a digital oscilloscope COR-5501 (26) manufactured by KIKUSUI. Channel2 (ch2). On the other hand, the straight laser beam is incident on the thermoelastic wave focusing device (24), detects the voltage responding to the incident infrared ray, and is amplified by the amplifier (25) of AE-9501 made by NF circuit design block and then the digital oscilloscope. It is input to channel 1 (ch1) of COR-5501 (26). The infrared detection apparatus is characterized in that a display of the infrared power or energy is obtained by digitizing the input in the two directions and processing it by a data processing computer (27).

Among the thermoelastic wave focusing devices (26) described above, the spherical thermoelastic wave focusing device shown in FIG. 1 uses an optical glass S-LAH79 ball lens having a diameter of 10 mm for the spherical solid (2), and the spherical The lens is provided with a cylindrical hole (3) having a diameter of 1.5 mm for the waveguide reaching the center, and an optical fiber having a diameter of 1 mm and a length of 18.8 mm is fixed to the hole as a waveguide (4). Yes. Further, a black coating is applied to the surface of the sphere that is coaxial with the cylindrical hole of the spherical lens as a light-sensitive part (1) as a coating that sensitively absorbs incident infrared rays, and the piezoelectric element (6) has an NF circuit design with a resonance frequency of 500 kHz. A block AE-904P PZT piezoelectric element is used.

Among the thermoelastic wave focusing devices (24) described above, the hemispherical thermoelastic wave focusing device shown in FIG. 2 is a hemispherical solid (9) made of BK-7 (borosilicate crown optical glass) Orion Optics. A 10 mm diameter hemispherical lens is used, and the sphere surface is coated with black as a coating that sensitively absorbs incident infrared rays so as to be coaxial with the central axis of the hemispherical lens. Uses an AE-904P PZT piezoelectric element manufactured by an NF circuit design block having a resonance frequency of 500 kHz.

Since the glass layer on the surface of the spherical lens is rapidly heated in proportion to the amount of heat absorbed when the light receiving part (1) of the spherical thermoelastic wave focusing device of FIG. Due to this, a spherical elastic wave is instantaneously generated, which passes through the elastic wave propagation region (8) and is focused at the center of the spherical lens to generate a large elastic wave. This is the thermal stress wave focusing phenomenon. Since the output elastic wave passes through the grease layer and is separated only into a longitudinal elastic wave and is converted into a voltage by the piezoelectric element (6), if the output voltage is measured, the energy intensity of the irradiated infrared rays can be accurately measured. .

FIG. 6 shows an example of a measurement result in which voltage output information in the spherical thermoelastic wave focusing device is recorded and stored as an elapsed time. The output of channel1 (ch1) responds to the input of channel2 (ch2). From FIG. 6, the response of the infrared detecting device of the present invention is very fast, about 4 μsec, and the gain laser energy intensity is displayed as a large voltage amplitude. The infrared detection method of the present invention detects the incident infrared intensity by the sum of the area (28) above the time axis and the area (29) below the time axis that the maximum amplitude of the first period of the voltage waveform is the time axis. It is characterized by doing.

FIG. 6 is an example of a measurement result in which the voltage output information in the spherical thermoelastic wave focusing device according to claim 2 is recorded and stored as an elapsed time, but the hemispherical thermoelastic wave focusing device according to claim 3 is used. It is clear that the same voltage output information can be obtained even when this is done.

FIG. 7 is a V · μsec-laser energy intensity characteristic curve obtained by the infrared detector of the present invention when a spherical thermoelastic wave focusing device made of an optical glass S-LAH79 ball lens having a diameter of 10 mm is used. The area V · μS is taken and the horizontal axis represents the incident infrared energy intensity. Therefore, if the value of the vertical axis is determined, the incident infrared intensity is determined.

FIG. 8 shows a case of using a hemispherical thermoelastic wave focusing apparatus using a hemispherical solid (2) and a hemispherical lens made of Orion Optics of BK-7 (borosilicate crown optical glass). This is a V · μsec-laser energy intensity characteristic curve obtained by an infrared detector, with the vertical axis representing V · μS and the horizontal axis representing incident infrared energy intensity. Since the characteristic curve has a substantially proportional relationship, the incident infrared intensity can be easily determined if the value of the vertical axis is determined.

The characteristic curves in FIGS. 7 and 8 are measured at room temperature, and the temperature rise due to the laser is about several degrees and does not affect the characteristic curve. When this experiment is performed at a high temperature of 1000 ° C. or higher, if the thermoelastic wave focusing device is made of a material that does not break at a high temperature, and the temperature correction is applied to the characteristic curve, the characteristic curve according to the present invention can be obtained even at a high temperature. It is clear that

FIG. 9 illustrates the principle of an infrared detection method for identifying the direction and power of the infrared emission source (13) from the incident infrared intensity distribution by the focusing device measurement panel (12) according to claim 5. In FIG. 9, for example, by rotating and moving the X axis, the X-ray absorption intensity distribution, which is a conical distribution measured by a plurality of thermoelastic wave focusing devices, has an isosceles triangular cross section. If the axis is fixed and the X ′ axis is set, the base angle and base length of the isosceles triangle are known, and the direction and distance of the laser emission source (13) and the power of the infrared emission source are detected from the absorbed infrared intensity. Can do.

The invention's effect

As described above, the infrared detection device according to claim 1 including the thermoelastic wave focusing device according to claim 2 and claim 3 includes a high-power laser by the detection method according to claim 4. It is possible to detect the response of intermittently excited infrared rays in a wide applicable wavelength range and at a very high speed of about 5 seconds, and the detector has a wide operating temperature range. In addition, since the structure of the infrared detection device of the present invention is very simple, there are few failures and low manufacturing costs. Further, by using the focusing device arrangement measuring panel constructed by combining a plurality of claims, the direction, distance and intensity of the laser source can be easily detected at any location. Therefore, it can be expected that the performance of the thermal infrared sensor is remarkably improved by the present invention.

  FIG. 1 is a block diagram of a spherical thermoelastic wave focusing device using a spherical solid.   FIG. 2 is a block diagram of a hemispherical thermoelastic wave focusing device using a hemispherical solid.   FIG. 3 is an explanatory diagram of a method for detecting the incident infrared energy intensity from the time-voltage curve output from the thermoelastic wave focusing device of the infrared detector of the present invention.   FIG. 4 is an explanatory view for explaining a detection method of an infrared emission source using a focusing device measuring panel formed by combining a plurality of thermoelastic wave focusing devices of the present invention.   FIG. 5 is a block diagram showing an embodiment of the infrared detecting device of the present invention.   FIG. 6 is an explanatory diagram of an incident infrared energy intensity detection method based on a time-voltage curve output from the thermoelastic wave focusing device in the embodiment of FIG.   FIG. 7 is a V · μsec-laser energy intensity characteristic curve in the spherical thermoelastic wave focusing device used in the embodiment of FIG.   FIG. 8 is a V · μsec-laser energy intensity characteristic curve in the hemispherical thermoelastic wave focusing device used in the embodiment of FIG.   FIG. 9 is an explanatory diagram for explaining a detection method of an infrared emission source using a focusing device measuring panel formed by combining a plurality of thermoelastic wave focusing devices of the present invention.

Explanation of symbols

19 mirror 20 convex lens 21 spectral plate 22 ND filter 23 calorimeter 26 digital oscilloscope 27 data processing computer

Claims (5)

Thermoelastic wave focusing consisting of a spherical thermoelastic wave focusing device or hemispherical thermoelastic wave focusing device exposed to receive the full infrared power including intermittently pumped medium or high power lasers And a focusing device that excites a thermoelastic wave proportional to the incident infrared ray and focuses it by a thermal stress wave focusing phenomenon, and then converts the elastic wave into an electrical signal by a piezoelectric element and converts the energy intensity of the incident infrared ray. Infrared detector characterized by detecting The spherical thermoelastic wave focusing device according to claim 1 is formed of a spherical solid (2) made of a material capable of withstanding a high temperature of 1000 ° C. or more, and is provided with a light receiving unit (1) coated with sensitive absorption of incident infrared rays. A cylindrical hole (3) reaching the center of the spherical solid (2) is provided, one end is fixed to the cylindrical hole (3), and the other end is joined to the piezoelectric element (6) with liquid viscous grease (5). After the thermoelastic wave is instantaneously excited by shock thermal expansion of the light receiving part (1) by incident infrared heating and focused in the elastic wave propagation region (8), Focusing on a spherical thermoelastic wave characterized in that the liquid viscous grease (5) adhering to the waveguide (4) is separated into only longitudinal acoustic waves by passing through the layer (5) and converted into an electrical signal by the piezoelectric element (6). apparatus. The hemispherical thermoelastic wave focusing device according to claim 1 is formed of a hemispherical solid (9) made of a material capable of withstanding a high temperature of 1000 ° C. or more, and is provided with a light receiving portion (1) that is sensitively absorbed by incident infrared rays. ) And a hemispherical solid (9) at the center position of the piezoelectric element (6) joined with the liquid viscous grease (5), and heat is generated instantaneously by the impact thermal expansion of the light receiving part (1) by incident infrared heating. After exciting the elastic wave and focusing in the elastic wave propagation region (8), it is separated into only the longitudinal wave elastic wave through the liquid viscous grease (5) layer and converted into an electric signal by the piezoelectric element (6). A hemispherical thermoelastic wave focusing device. The output information by the conducting wire (7) directly connected to the thermoelastic wave focusing device according to claim 1 is recorded and stored as a voltage waveform as a time function, and the time when the maximum amplitude of the first period of the waveform is a time axis is recorded. An infrared ray detecting method, wherein the incident infrared ray intensity is detected by a sum of an area (10) above the axis and an area (11) below the time axis. A focusing device measuring board (12) configured by closely coupling a plurality of thermoelastic wave focusing devices according to claim 1 in a plane is three-dimensionally swung around the X, Y, and Z axes. An infrared detection method characterized by detecting the direction and distance of an incident infrared ray emission source (13) from the incident infrared ray intensity distribution, and further detecting the energy intensity of the emission source by moving the infrared ray.

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