JP2005106521A - Semiconductor laser unit and gas concentration measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely emit a measurement light beam toward a measurement position, by confirming the emission position of the measurement light beam. <P>SOLUTION: In the semiconductor laser unit 4, a light receiver 9 is disposed at the bottom on the central axial line L-L inside a cylindrical main body 5 with bottom, and a semiconductor laser module 11 including a semiconductor laser 11c, a laser pointer 12 for emitting a visible light beam as a guide light beam, and a multiplexing/demultiplexing means 13 disposed on the optical axis of the light receiver 9, for multiplexing the measurement light beam emitted from the semiconductor laser 11c and the guide light beam emitted from the laser pointer 12 on approximately the same axis, are incorporated into the main body 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention uses a semiconductor laser as a light source and optically measures gas concentration using light absorption, for example, piping facilities in city gas, chemical plants, etc., gas leakage due to deterioration of high-voltage power transmission lines, and in coal mines Gas concentration measurement that can be periodically calibrated when measuring gas concentration or measuring system construction without disturbing the measurement system when detecting leaked gas, gas generated from landfills, exhaust gas components of transportation equipment, etc. The present invention relates to a semiconductor laser unit and a gas concentration measuring device used in the apparatus.

  It is already known that gases such as methane, carbon dioxide, acetylene, and ammonia have an absorption band that absorbs light of a specific wavelength according to molecular rotation, vibration between constituent atoms, and the like. In a gas concentration measurement apparatus using this absorption band, a light source unit and a light receiving unit are arranged at a predetermined distance (the measurement optical path length is determined by this distance), and laser light frequency-modulated by a semiconductor laser of the light source unit is used. The gas concentration of the measurement target gas is measured from an output signal when the transmitted light is passed through the atmosphere of the measurement target gas and received by the photo detector of the light receiving unit. Even if the light source unit and the light receiving unit are arranged at the same position, the measurement optical path length is secured if the measurement light can be received as reflected light.

  Here, a large offset due to intensity modulation occurs in a fundamental sensitive detection signal (hereinafter referred to as “1f signal”) having a modulation frequency detected from the output signal of the light receiving unit. For this reason, in order to measure a particularly minute gas concentration with high sensitivity, a second harmonic phase sensitive detection signal (hereinafter abbreviated as 2f signal) having a considerably smaller offset than the 1f signal is used.

  When actually measuring the gas concentration, when the measurement light with the wavelength matched to the measurement gas absorption line passes through the measurement gas atmosphere, the measurement light is absorbed by the measurement gas, and the intensity corresponding to the concentration is twice the modulation frequency. Is generated, that is, 2f. Since the value of the intensity change ratio 2f / 1f between 2f and the original modulation frequency 1f is proportional to the gas concentration, the gas concentration is obtained by multiplying this value by a coefficient.

  By the way, the oscillation wavelength of a semiconductor laser has the property of changing depending on the operating temperature of the semiconductor laser. In addition, the oscillation wavelength varies depending on the value of the current flowing through the semiconductor laser. Therefore, in order to obtain a stable 2f signal, it is necessary to stabilize the oscillation wavelength of the semiconductor laser by making it coincide with the center of the absorption line. In general, a semiconductor laser oscillation wavelength stabilization device using a semiconductor laser module passes a laser beam through a reference gas cell in which a measurement target gas as a wavelength stabilization gas is sealed. Then, the operating temperature or current of the semiconductor laser is changed so that the maximum absorption point is found by using one absorption line of the measurement target gas and located there. In other words, the maximum absorption point is stabilized by changing the operating temperature or current of the semiconductor laser.

  Here, the configuration of a conventional reflective gas concentration measuring apparatus will be described with reference to FIGS. 19 is a front view showing an example of an optical unit of a conventional reflective gas concentration measuring device, FIG. 20 is a side view of the optical unit, FIG. 21 is a diagram showing an example of a measuring unit, and FIG. 22 is an example of a light source unit. FIG. 23 is a front view showing another example of the optical unit of the conventional reflective gas concentration measuring device, FIG. 24 is a side view of the optical unit, and FIG. 25 is a diagram of a light source unit incorporated in the optical unit of FIG. It is a figure which shows an example.

  As a conventional reflective gas concentration measuring apparatus, an apparatus including an optical unit 100 shown in FIGS. 19 and 20 and a measuring unit 101 shown in FIG. 21 is known. In this gas concentration measuring apparatus, a light source unit 102 as shown in FIG. 22 disclosed in, for example, Patent Document 1 shown below is built in the measurement unit 101 shown in FIG. 21, and an optical fiber is provided between the light source unit 102 and the optical unit 100. 103.

  As shown in FIGS. 19 and 20, the optical unit 100 includes a bottomed cylindrical main body 104 that is open on one side and a gripping part 105 that grips the main body 104. Yes. A condensing lens 106 made of, for example, a Fresnel lens for condensing the reflected measurement light is installed in the opening 104 a of the main body 104. The center of the condenser lens 106 is an emission position from which the measurement light is emitted, and an emission unit 107 that emits the measurement light is provided at the emission position. The emitting unit 107 is connected to the light source unit 102 in the measuring unit 101 through the main body 104 by the optical fiber 103. At the back of the opening 104 a of the main body 104, a light receiver 108 is provided that collects and receives the reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted from the emission unit 107 by the condenser lens 106. It has been. The reflected measurement light received by the light receiver 108 is converted into an electrical signal and then sent to the measurement unit 101 via a wiring cable (not shown). In addition, a laser pointer 109 that emits visible light for visually confirming a measurement position from which measurement light is emitted is provided on the outer periphery of the front end of the main body 104.

  A measurement unit 101 shown in FIG. 21 includes a switch for performing various settings, a display for displaying measurement data, and the like on the front panel, is driven by a battery, and is portable by a carrying case (not shown). The light source unit 102 built in the measurement unit 101 generates laser light having a wavelength that matches the absorption line specific to the measurement gas. In the light source unit 102, as shown in FIG. 22, a semiconductor laser module 111, a reference gas cell 112, and a photo detector 113 are accommodated inside a box-shaped case body 110 made of a metal package. Although not shown, a semiconductor laser (laser diode) that emits frequency-modulated laser light from both sides is provided in the case (butterfly module) 114 of the semiconductor laser module 111. An optical fiber 103 provided with a connector 115 is extended from the case 114, and one light emitted from the semiconductor laser is guided to the emission unit 107 through the optical fiber 103 as measurement light. A temperature control element (Peltier element) 117 to which a cooling fin 116 is attached is provided on the bottom surface of the case body 110. Since the semiconductor laser has the property that the oscillation wavelength changes depending on the operating temperature and the operating current, the oscillation wavelength is controlled by controlling the operating temperature to a constant temperature by the temperature control element 117 installed under the LD chip carrier inside the butterfly module. Be controlled.

  As another reflective gas concentration measuring apparatus, an apparatus including an optical unit 200 shown in FIGS. 23 and 24 and a measuring unit 101 that does not incorporate the light source unit 102 in FIG. 21 is known. In addition, the same number is attached | subjected to the same component as the reflective gas concentration measuring apparatus mentioned above, and the description is abbreviate | omitted.

  In this gas concentration measuring apparatus, since the light source unit 102 is not built in the measuring unit 101, as shown in FIGS. 23 and 24, for example, disclosed in the following Patent Document 1 at the central emission position of the condenser lens 106 in the optical unit 200. A light source unit 300 as shown in FIG. 25 is provided.

  As shown in FIG. 25, in the light source unit 300, a semiconductor laser 303 is disposed on the central axis of a cylindrical case 302 having a protective glass 301 fixed to an inclined front surface. The semiconductor laser 303 is mounted on a temperature control element (Peltier element) 306 attached to the surface of the base 305 on the substrate 304 in the cylindrical case 302 in order to enable temperature control. Aspherical lenses 307 (307a and 307b) having no flat surface are fixed to the mounting base 308 on the optical axes on both the front and rear sides of the semiconductor laser 303. An optical isolator 309a is disposed between the protective lens 301 and the aspherical lens 307a on the optical axis on the front side of the semiconductor laser 303. Further, a reference gas cell 310 is disposed on the optical path behind the semiconductor laser 303. A photo detector 311 is disposed on the optical path behind the reference gas cell 310. Further, an optical isolator 309 b is also disposed between the aspheric lens 307 b and the reference gas cell 310 on the optical path behind the semiconductor laser 303.

As described above, in the conventional reflective gas concentration measurement apparatus, the measurement light from the light source unit 102 built in the measurement unit 101 is output by the optical fiber 103 to the emission position of the optical unit 100 (the emission unit 107 at the center of the condenser lens 106). ) Or the light source unit 300 is disposed at the emission position (the emission part 107 at the center of the condenser lens 106) and emitted.
JP 2001-235420 A

  However, in the conventional reflective gas concentration measuring device, the optical fiber 103 uses the optical fiber 103 in the light guide configuration, so that a loss occurs when introducing the measurement light from the semiconductor laser of the light source unit 102 into the optical fiber 103. Occurs and the light intensity is about half. For this reason, the level of the measurement light actually emitted toward the measurement atmosphere is also reduced, and there is a possibility that stable and accurate measurement cannot be performed.

  On the other hand, in the configuration in which the light source unit 300 is disposed in the center of the condenser lens 106, the light source unit 300 itself that is conventionally used is large. Get in the way. As a result, the amount of measurement reflected light received from the measurement atmosphere is greatly reduced, resulting in a problem that measurement accuracy is lowered. In addition, in this type of conventional light source unit 300, the apparatus for stabilizing the measurement light wavelength is arranged outside the butterfly module that forms the outer casing of the semiconductor laser module 111, and the outer shape is large and the weight is heavy. It cannot be easily attached to the optical unit 200.

  Furthermore, in this type of reflective gas concentration measuring apparatus, the measurement light is invisible because of infrared rays. For this reason, a laser pointer 109 is provided on the outer periphery of the tip of the main body 104 of the optical unit 100 (or 200) so that the location where the measurement light is emitted can be confirmed by visible light. Thereby, visible light visible at the time of measurement is emitted from the laser pointer 109 so that it can be confirmed that the measurement light is emitted several centimeters above the emitted light hitting the reflecting wall. However, since there is a deviation between the measurement position and the position where the measurement light and the visible light hit, there is a difference between individuals when the optical unit 100 (or 200) is directed to the measurement position. It was difficult to make accurate measurements.

  Accordingly, the present invention has been made in view of the above problems, and provides a semiconductor laser unit capable of confirming the emission position of the measurement light and accurately emitting the measurement light toward the measurement position. The first object is to provide a gas concentration measuring device capable of performing stable and highly accurate measurement without individual differences by using a semiconductor laser unit. In addition, the oscillation wavelength of the semiconductor laser is stabilized. And a semiconductor laser unit that can be mounted in a plurality of semiconductor laser modules. The object is to provide a gas concentration measuring device.

In order to achieve the above object, in the semiconductor laser unit according to claim 1 of the present invention, the semiconductor laser 11c emits the measurement light frequency-stabilized by the gas absorption line to the measurement atmosphere, Reflected measurement light reflected from the measurement atmosphere as it is emitted is received by a light receiver 9, and a fundamental phase sensitive detection signal and a second harmonic phase sensitive detection signal of the modulation frequency of the semiconductor laser are output from the output signal of the light receiver. A semiconductor laser unit 4 used in a gas concentration measuring apparatus 1 for detecting a signal and measuring a gas concentration in the measurement atmosphere based on a ratio of both signals;
A semiconductor laser module 11 comprising a gas cell filled with the same type of gas as the semiconductor laser and the concentration measurement target gas, and emitting the measurement light;
A laser pointer 12 that emits visible light as guide light for guiding the measurement light to the measurement atmosphere;
A multiplexing / demultiplexing means 13 for multiplexing the measurement light and the guide light substantially coaxially is provided.

  The semiconductor laser unit according to claim 2 is the semiconductor laser unit according to claim 1, wherein the multiplexing / demultiplexing means 13 includes a reflection mirror 21 that reflects the measurement light and the measurement reflected by the reflection mirror. A dichroic mirror 22 that combines light and the guide light substantially coaxially is provided.

  According to a third aspect of the present invention, there is provided the semiconductor laser unit according to the second aspect, further comprising an optical axis adjustment mechanism unit 17 that adjusts an emission direction of the measurement light reflected by the reflection mirror 21. Features.

In the semiconductor laser unit according to claim 4, the semiconductor laser 11c emits the measurement light frequency-stabilized by the gas absorption line to the measurement atmosphere, and is reflected from the measurement atmosphere as the measurement light is emitted. The reflected measurement light is received by the photoreceiver 9, and the fundamental phase sensitive detection signal and the double phase sensitive detection signal of the modulation frequency of the semiconductor laser are detected from the output signal of the photoreceiver, and the ratio of the two signals is detected. A semiconductor laser unit 4 used in a gas concentration measuring apparatus 1 for measuring a gas concentration in the measurement atmosphere based on
A plurality of semiconductor laser modules 11 each having a gas cell filled with the same type of gas as the semiconductor laser and the concentration measurement target gas and emitting laser beams of different wavelengths corresponding to gas absorption lines as the respective measurement lights;
A laser pointer 12 that emits visible light as guide light for guiding each measurement light to the measurement atmosphere;
The multiplexing / demultiplexing means 13 includes a reflection mirror 21 that reflects the predetermined measurement light among the plurality of measurement lights, and the predetermined measurement light and the predetermined measurement light among the plurality of measurement lights. And a multiplexing / demultiplexing means 13 for multiplexing the predetermined measurement light and the visible light on substantially the same axis.

The semiconductor laser unit according to claim 5 is the semiconductor laser unit according to claim 1, wherein the semiconductor laser module 11 includes the semiconductor laser 11c,
A collimating lens 11d for converting measurement light emitted from the semiconductor laser into parallel light;
An optical isolator 11e for suppressing return of reflected light to the semiconductor laser;
A temperature measuring element 11i for measuring the temperature of the semiconductor laser;
A temperature control element 11f for controlling the temperature of the semiconductor laser;
The gas cell 11g;
A light receiver 11h that receives laser light emitted backward from the semiconductor laser after passing through the gas cell is incorporated in a butterfly case 11a and hermetically sealed.

The gas concentration measuring apparatus according to claim 6 includes a cylindrical main body 5 having a bottom,
A semiconductor laser unit 4 according to any one of claims 1 to 5;
A light receiver disposed in the main body 5 and in the vicinity of the central axis LL of the main body;
Condensing means 7 that is installed in the opening 5a of the main body, receives reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted from the semiconductor laser unit, and focuses the light on the light receiver, Condensing means 7 having a window portion 8 that allows the measurement light and the guide light from the laser pointer 12 to pass in the vicinity of the central axis of the condensing means;
Measurement units 3a, 3b, and 3c that convert the reflected measurement light collected by the light collecting means and received by the light receiver into an electrical signal and calculate a gas concentration based on the electrical signal, It is characterized by being integrally provided inside.

  According to the present invention, the measurement light for measuring the concentration of the measurement target gas and the guide light for confirming the emission position of the measurement light are emitted substantially coaxially. It can be confirmed accurately by the guide light, the optical part can be easily directed toward the measurement location, and the measurement light can be emitted, and the gas concentration at the fine measurement location can be measured accurately.

  If the optical axis adjustment mechanism 17 is provided, the emission direction of the measurement light reflected by the reflection mirror 21 can be finely adjusted.

  By preparing a plurality of semiconductor laser modules 11 that emit measurement light of different wavelengths and setting the modulation frequency at the time of frequency control to the gas absorption line to a different value for each semiconductor laser module 11, a plurality of types of gas concentrations Can be measured at once.

  If each component including the ultra-small gas cell 11g is accommodated and sealed in the butterfly-type case body 11a of the semiconductor laser module 11, the semiconductor laser module 11 incorporated in the semiconductor laser unit 4 can be reduced in size. Can do.

  Since the semiconductor laser unit 4 that has been reduced in size is incorporated in the main body 5 and no optical fiber is used when the measurement light from the semiconductor laser 11c is guided to the window portion 8, the measurement light can be measured without causing any loss. It is possible to emit light toward the center and to perform stable and accurate measurement. In addition, when the reflected measurement light is condensed on the light receiver 9 by the condenser lens 7, there is little light blocked by other components, and the reflected measurement light from the measurement atmosphere can be received with a sufficient amount of received light, and the measurement accuracy Can be prevented.

  1 is a front view of a gas concentration measuring device including a semiconductor laser unit according to the present invention, FIG. 2 is a side view of the gas concentration measuring device, and FIG. 3 is an example of a semiconductor laser unit employed in the gas concentration measuring device. 4 is a side view of the semiconductor laser unit, FIG. 5 is a plan sectional view of a semiconductor laser module constituting a part of the semiconductor laser unit according to the present invention, and FIG. 6 is a plan view of the semiconductor laser unit according to the present invention. FIG. 7 is a side view of the optical axis adjustment mechanism, FIG. 8 and FIG. 9 are other configuration examples of the semiconductor laser unit employed in the gas concentration measuring apparatus according to the present invention. FIG.

  As shown in FIGS. 1 and 2, a gas concentration measuring apparatus 1 according to the present invention has a configuration in which a measuring unit 3 is integrated into an optical unit 2. The optical unit 2 includes a bottomed cylindrical main body 5 having an open surface and a semiconductor laser unit 4 mounted therein, and a gripping unit 6 that is positioned on the rear end side of the main body 5 and grips the main body 5. The appearance is gun-shaped. The grip 6 is provided with a trigger type measurement button 6a. The measurement button 6a is operated to start measurement and stop measurement by the pushing operation. Only at the start of measurement, measurement light and guide light are emitted to the outside (measurement atmosphere).

  The main body 5 is not limited to a cylinder as long as the main body 5 has a bottomed cylindrical shape with one surface opened. Moreover, it is preferable that the main body 5 has a horn shape whose diameter is widened from the bottom toward the tip, and a shape that effectively receives the reflected measurement light by increasing the effective area for receiving the reflected measurement light as much as possible.

  A condensing lens 7 as a condensing means is provided in the opening 5 a of the main body 5. The condensing lens 7 is composed of, for example, a Fresnel lens, receives reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted to the measurement atmosphere, and condenses it on a light receiver 9 described later. In the center of the condenser lens 7 (on or near the central axis LL in FIG. 2), a window portion 8 through which the measurement light and the guide light are emitted is provided. The window portion 8 is configured by a window made of, for example, glass that is fixed at a predetermined angle with respect to the condenser lens 7. As shown in FIG. 2, a light receiver 9 is provided at the back (bottom) on the central axis LL in the main body 5. The light receiver 9 receives the reflected measurement light reflected from the measurement atmosphere and condensed by the condenser lens 7 as the measurement light is emitted. The reflected measurement light received by the light receiver 9 is converted into an electrical signal and then sent to the measurement unit 3 for signal processing. A semiconductor laser unit 4 is provided near the condenser lens 7 in the main body 5.

  The semiconductor laser unit 4 generates laser light having a wavelength that matches the absorption line peculiar to the measurement gas, and guide light (laser light) emitted from a laser pointer 12 (to be described later) substantially coincides with the emission axis from a predetermined position. It emits measurement light.

  As shown in FIGS. 3 and 4, the semiconductor laser unit 4 includes a semiconductor laser module 11, a laser pointer 12, a multiplexing / demultiplexing unit 13, a support member 14, an insulating member 15, a radiator 16, and an optical axis adjustment mechanism unit 17. In general, it is configured. The semiconductor laser unit 4 has a rectangular radiator 16 as a base, and each component is disposed on the radiator 16.

  As shown in FIG. 5, the semiconductor laser module 11 is based on a box-shaped butterfly-type case body 11a having a plurality of pairs of electrodes. A through hole (not shown) is formed on one surface of the butterfly type case main body 11a, and an emission window 11b such as glass is provided in the through hole. The semiconductor laser module 11 includes a semiconductor laser 11c, a collimating lens 11d, an optical isolator 11e, a Peltier element 11f as a temperature control element, a gas cell 11g, a photodiode 11h as a light receiver, and a thermistor 11i as a temperature measurement element. 11a, the optical axis of each optical component is adjusted and hermetically sealed.

  The semiconductor laser 11c emits laser light whose frequency is modulated by controlling the oscillation wavelength to the measurement wavelength from both the front and rear surfaces. The laser light emitted from the front surface is used as measurement light and is emitted from the rear surface. Laser light is used as reference light. The collimating lens 11d is disposed on the emission window 11b side in front of the semiconductor laser 11c, and collimates the measurement light emitted from the semiconductor laser 11c into parallel light. The optical isolator 11e is disposed on the exit window 11b side in front of the collimating lens 11d. The optical isolator 11e applies a magnetic force to a crystal disposed between a polarizer that passes only light with a 90 ° polarization plane and an analyzer that passes only light with a 45 ° polarization plane. The polarization plane of the transmitted laser light is rotated to prevent the reflected light from passing through the polarizer. Thereby, the return of the reflected light to the semiconductor laser 11c due to the emission of the laser light from the semiconductor laser 11c is suppressed. The measurement light converted into parallel light by the collimating lens 11d is emitted to the outside from the emission window 11b via the optical isolator 11e. A Peltier element 11f as a temperature control element controls the temperature of the semiconductor laser 11c. The reference gas cell 11g is disposed behind the semiconductor laser 11c and encloses a wavelength stabilizing gas, and is used for frequency stabilization of the oscillation wavelength of the measurement light. Although the configuration and manufacturing method of the gas cell 11g will be described later, the gas cell 11g is configured to be ultra-small, for example, about 6 mm in length having an absorption line specific to the specific gas. The photodiode 11h is disposed behind the gas cell 11g and receives and detects reference light from the semiconductor laser 11c that has passed through the gas cell 11g. The thermistor 11i detects the temperature of the semiconductor laser 11c.

  The laser pointer 12 is provided on the optical axis (LL) of the condenser lens 7 where the window 8 is located. The laser pointer 12 is provided with a semiconductor laser 12b on a cylindrical main body 12a. The semiconductor laser 12b can visually check the emission position of the measurement light, and emits visible light as guide light for guiding the measurement light to the measurement atmosphere.

  The multiplexing / demultiplexing means 13 includes a reflecting mirror 21 and a dichroic mirror 22. The reflection mirror 21 is located in front of the semiconductor laser module 11, is attached to the optical axis adjustment mechanism 17 shown in FIGS. 6 and 7, and is disposed on the radiator 16. The reflection mirror 21 reflects the measurement light emitted from the semiconductor laser 11 c of the semiconductor laser module 11 to the dichroic mirror 22 side.

  The dichroic mirror 22 is positioned above the reflecting mirror 21 and in front of the semiconductor laser 12 b of the laser pointer 12 and is fixed to the main body 12 a of the laser pointer 12. The dichroic mirror 22 reflects the measurement light reflected by the reflection mirror 21 so as to be emitted from the optical unit 2 toward the measurement atmosphere. Further, the dichroic mirror 22 transmits the guide light emitted from the laser pointer 12, and is combined with the measurement light and emitted substantially coaxially. According to the dichroic mirror 22, 99% or more of the measurement light can be reflected and 80% or more of the guide light can be transmitted.

  The support member 14 has a function of supporting the laser pointer 12 to which the dichroic mirror 22 is fixed. The support member 14 is formed so that the projected area becomes as small as possible without reducing the effective area of the condenser lens 7 that collects the reflected measurement light when viewed from the front. In the example of FIG. 3, the support member 14 is formed by bending a thin plate member into an inverted V shape, supports the laser pointer 12 to which the dichroic mirror 22 is fixed at the arcuate apex portion, and has legs on both sides. Each tip portion of the portion 14 a is fixed to the surface of the radiator 16.

  The insulating member 15 is formed in a plate shape around the semiconductor laser 12 b and is provided between the semiconductor laser module 11 and the radiator 16. The insulating member 15 has a function of thermally insulating the semiconductor laser module 11 and the radiator 16 to prevent heat from entering.

  3 and 4, the heat radiator 16 is disposed so as to be exposed to the outside from the main body 5 when incorporated in the main body 5, and has a function of radiating heat generated from the semiconductor laser module 11 to the outside.

  The optical axis adjustment mechanism unit 17 adjusts the angle of the reflection mirror 21 so that the measurement light from the semiconductor laser module 11 is reflected to the dichroic mirror 22 side at a predetermined angle, and finely adjusts the optical axis. The specific configuration will be described. As shown in FIGS. 6 and 7, the optical axis adjusting mechanism portion 17 has a pair of adjusting arms 24 integrally formed on both sides of a rectangular mounting portion 23 having a concave portion 23a at the center. ing. The concave portion 23a of the mounting portion 23 forms a mounting surface inclined at a predetermined angle (approximately 45 °) to which the reflection mirror 21 is mounted. The end portions 24a of the pair of adjustment arms 24 are fixed to a mounting part (the heat radiator 16 in the configuration of FIG. 1) by a fixing screw 25. On both sides of the mounting portion 23, an adjustment screw 26 is provided so that the tip 26a contacts the surface of the mounting component (the surface of the radiator 16 in the configuration of FIG. 1).

  According to the optical axis adjusting mechanism 17, by rotating one or both of the adjusting screws 26 of the mounting portion 23, the mounting portion 23 moves up and down with the tip portions 24 a of the pair of adjusting arms 24 as fulcrums. The angle of the reflecting mirror 21 provided in the recess 23a can be adjusted.

  By the way, in the gas concentration measuring apparatus 1 of this example, in order to measure a plurality of gases, as shown in FIGS. 8 and 9, a plurality of semiconductor laser modules 11 having different oscillation wavelengths (two in the illustrated example) are mounted. It is also possible to employ the semiconductor laser unit 4. In this case, the multiplexing / demultiplexing means 13 includes a reflection mirror 21 that reflects a predetermined measurement light of the plurality of measurement lights, and measures other than the predetermined measurement light among the predetermined measurement light and the plurality of measurement lights. The light is multiplexed substantially coaxially, and the predetermined measurement light and visible light are multiplexed approximately coaxially. Hereinafter, the configuration of the semiconductor laser unit 4 of FIGS. 8 and 9 will be described as a specific example. In addition, the same number is attached | subjected to the component same as FIG. 2, and the description is abbreviate | omitted.

  In the semiconductor laser unit 4 shown in FIG. 8, the multiplexing / demultiplexing means 13 includes a reflection mirror 21, a dichroic mirror 22, and a beam splitter 27. The semiconductor laser unit 4 shown in FIG. 8 is fixed by a mounting plate 28 in a state where two radiators 16 (16A, 16B) are overlapped at a predetermined interval. The semiconductor laser module 11 is disposed on the lower radiator 16 </ b> A, and the reflection mirror 21 is disposed in front of the semiconductor laser module 11. The semiconductor laser module 11 is also disposed on the upper radiator 16B, and a beam splitter 27 is disposed on the optical path of the measurement light reflected by the reflection mirror 21 in front of the semiconductor laser module 11. The beam splitter 27 has a function of reflecting measurement light by 50% and transmitting 50%, for example. In addition, a support member 14 that supports the laser pointer 12 is provided in the upper radiator 16B. A dichroic mirror 22 is attached to the laser pointer 12 on the optical path of the two-wavelength measurement light combined by the beam splitter 27. The dichroic mirror 22 multiplexes the measurement light having different wavelengths emitted from the respective semiconductor laser modules 11 and synthesized by the beam splitter 27 and the guide light from the laser pointer 12 on substantially the same axis.

  In the semiconductor laser unit 4 shown in FIG. 9, as in FIG. 8, the multiplexing / demultiplexing means 3 includes a reflection mirror 21, a dichroic mirror 22, and a beam splitter 27. In the semiconductor laser unit 4 shown in FIG. 9, the semiconductor laser modules 11 are respectively disposed on both surfaces (upper and lower surfaces) of the plate-like heat conductor 29. The heat conductor 29 is provided with a radiator 16. The heat conductor 29 has a function of conducting heat generated in each semiconductor laser module 11 to the heat radiator 16. A reflection mirror 21 is disposed in front of the semiconductor laser module 11 disposed on the lower surface of the heat conductor 29. A beam splitter 27 is disposed on the optical path of the measurement light reflected by the reflection mirror 21 in front of the laser module 11 disposed on the upper surface of the heat conductor 29. The heat conductor 29 is provided with a support member 14 that supports the laser pointer 12. A dichroic mirror 22 is attached to the laser pointer 12 on the optical path of the two-wavelength measurement light combined by the beam splitter 27. According to this configuration, it is possible to make the structure easy to mount by reducing the height of the unit as compared with the semiconductor laser unit of FIG.

  8 and 9, the two semiconductor laser modules 11 are arranged. However, three or more semiconductor laser modules 11 can be arranged. For example, in the configuration of FIG. 8, a plurality of semiconductor laser modules 11 that emit measurement light having different wavelengths are arranged on a plurality of radiators 16, and the plurality of radiators 16 are arranged at predetermined intervals in the vertical direction. To fix. A beam splitter 27 is provided in front of the semiconductor laser module 11 of the radiator 16 disposed at the top, a support member 14 that supports the laser pointer 12 is provided, and the dichroic mirror 22 is attached to the laser pointer 12. Further, a beam splitter 27 is disposed in front of the semiconductor laser module 11 of the radiator 16 positioned below the uppermost radiator 16, and a reflection mirror is positioned in front of the semiconductor laser module 11 of the radiator 16 positioned at the lowermost position. 21 is arranged. As a result, the measurement light beams having different wavelengths from the respective semiconductor laser modules 11 are combined by the beam splitter 27, and the measurement light beams having a plurality of wavelengths and the guide light are multiplexed substantially coaxially by the dichroic mirror 22.

  Further, when the multiplexing / demultiplexing means 13 includes the reflecting mirror 21, the dichroic mirror 22, and the beam splitter 27, the optical axis adjusting mechanism 17 described with reference to FIGS. 6 and 7 is used as the reflecting mirror 21 and the beam splitter 27. By adopting it, it is possible to adopt a configuration in which not only the reflection mirror 21 but also the optical axis of the beam splitter 27 can be adjusted.

  Further, if a dichroic mirror 22 having the characteristics of transmitting measurement light and reflecting guide light is employed, the semiconductor in the semiconductor laser unit 4 of this example shown in FIGS. 2, 4, 8, and 9, for example. The positional relationship between the laser module 11 and the semiconductor laser 12b of the laser pointer 12 may be reversed.

  The measuring unit 3 is incorporated in a position that does not interfere with the emission and reflected measurement light of the measurement light inside the main body 5, and is provided behind the light receiver 9 at the bottom of the main body 5 in the example of FIG. 2. As shown in FIG. 2, the measurement unit 3 includes a measurement light amplification unit 3a, a light reception signal detection unit 3b, a calculation unit 3c, and a wavelength stabilization circuit 3d.

  The measurement light amplifying unit 3a is composed of a preamplifier, and the amplification degree is 1f signal and 2f signal so that the 1f signal and 2f signal detected by the received light signal detection unit 3b have the same detection level in the measurement target gas concentration range. The optimal amplification level is set. In the measurement light amplification unit 3a, the light reception current of the measurement light signal detected and output from the light receiver 9 is converted into a light reception voltage, and further amplified and output with a set amplification factor.

  The received light signal detector 3b performs signal processing on the measurement light signal amplified by the measurement light amplifier 3a, and phase-sensitively detects the 1f signal and the 2f signal.

  The calculation unit 3c receives the 1f signal and the 2f signal from the received light signal detection unit 3b, and calculates the gas concentration of the measurement target gas based on the ratio (2f / 1f).

  The wavelength stabilization circuit 3d performs processing related to search for set temperature, initial setting, second harmonic peak stabilization, signal synchronization detection, and second harmonic distortion suppression operation. The description is omitted because it is the same as the above.

  Here, the configuration of the gas cell 11g incorporated in the semiconductor laser module 11 will be described. 10 is a cross-sectional view showing the first form of the gas cell, FIG. 11 is a cross-sectional view showing the second form of the gas cell, FIG. 12 is a cross-sectional view showing the third form of the gas cell, and FIG. 13 is a cross-sectional view showing the fourth form of the gas cell. 14 and 14 are sectional views showing a fifth embodiment of the gas cell.

  First, the gas cell 11g according to the first embodiment will be described. In addition, the manufacturing method etc. of the gas cell 11g of each form are demonstrated later. As shown in FIG. 10, the gas cell 11g of the first form includes the first main body portion 32A (32) and the second main body portion having the same shape manufactured using metal materials that can be joined by welding as constituent parts. 33A (33) and a spacer member 34 used when the first main body portion 32A and the second main body portion 33A are joined to each other. The first main body portion 32A and the second main body portion 33A are formed using a material (for example, kovar, iron-nickel alloy, copper-nickel alloy, etc.) that can be joined and has a linear expansion coefficient as small as possible. In addition, it is desirable that this material is subjected to rust prevention treatment by, for example, Ni plating. The first main body portion 32A and the second main body portion 33A need only have a thickness that does not greatly deform due to the difference between the gas pressure and the atmospheric pressure in the gas cell 31 that is completed when the gas is sealed.

  The first main body portion 32A and the second main body portion 33A are formed in a concave shape having openings 32a and 33a and bottom portions 32b and 33b. The collar portions 32c and 33c are suspended from the outer peripheral edge portions of the opening 32a of the first main body 32A and the opening 33a of the second main body 33A. In the flange portions 32c and 33c, the surfaces (bonding surfaces) facing each other when the first main body portion 32A and the second main body portion 33A are bonded form a flat surface. On the openings 32a and 33a side of the flange portions 32c and 33c, for example, protrusions 32d and 33d having a mountain-shaped cross section are formed along the outer periphery. Through holes 32f and 33f provided with windows 32e and 33e are formed in the bottom portions 32b and 33b of the first main body portion 32A and the second main body portion 33A. The windows 32e and 33e are formed of a material (for example, glass or the like) that does not attenuate transmitted light by the absorption wavelength of the sealed gas.

As a method of providing the glass constituting the windows 32e and 33e, a method of directly fixing the glass to the main body portions 32A and 33A using low melting glass, a method of providing the main body portions 32A and 33A with metallization for solder fixing on the glass, There is a method of fixing by soldering, but it is preferable to use the main body portions 32A and 33A with windows for CAN type LD modules that can be joined. This is optimal for the window because it is inexpensive and can provide a gas density of about 10 ⁻⁸ to 10 ⁻⁹ atm · cc / sec.

  The spacer member 34 is provided between the first main body portion 32A and the second main body portion 33A, and the flange portion 32c of the first main body portion 32A and the flange portion 33c of the second main body portion 33A are opposed to each other. The spacer member 34 is made of the same metal material as the first main body portion 32A and the second main body portion 33A. The spacer member 34 has a flat plate member as a base, and a through hole 34b having a diameter larger than the diameters of the window portions 32e and 33e of the first main body portion 32A and the second main body portion 33A is formed in the center thereof. A cylindrical flange 34a is integrally formed on both surfaces of the spacer member 34 along the peripheral edge of the through hole 34b. When the spacer member 34 is interposed between the first main body portion 32A and the second main body portion 33A, the flange 34a has flanges 32c and 33c (protrusions) of the first main body portion 32A and the second main body portion 33A. 32d, 33d) serve as a guide for reliably positioning the spacer member 34 on the plane.

  And when manufacturing the gas cell 11g of the said 1st form, the gas cell manufacture mentioned later is made by facing the opening parts 32a and 33a of the 1st main-body part 32A and the 2nd main-body part 33A, and interposing the spacer member 34 between them. Set in the jig 42, and fill in the openings 32a and 33a of the first main body portion 32A and the second main body portion 33A so as not to react with the target gas (the same kind of gas as the gas concentration detection gas or the gas concentration detection gas). After the gas is sealed, the gas is hermetically sealed by resistance welding between the protrusions 32d and 33d of the flanges 32c and 33c of the first main body 32A and the second main body 33A and the flat surface of the spacer member 34. To do.

  In the gas cell 11g of the first embodiment, the first main body portion 32A and the second main body portion 33A have protrusions 32d having a mountain cross section so as to come into contact with a predetermined resistance value so that the resistance value of the joint surface is increased. Although the example of forming 33d has been described, the protrusions may be formed on the spacer member 34 facing the flanges 32c and 33c. Further, the protrusions 32d and 33d are necessary when the thickness ratio of the surfaces to be joined is three times or more. Therefore, if the thickness ratio of the surfaces to be joined is less than three times, the protrusions 32d and 33d need not be formed.

  In the gas cell 11g of the first form, the flange 34a is provided on the outer periphery of the through hole 34b of the spacer member 34. However, the flange 34a does not overlap the windows 32e and 33e, and the first main body 32A and What is necessary is just to provide in the position which can position the 2nd main-body part 33A. Moreover, it is good also as a structure only of the 1st main-body part 32A and the 2nd main-body part 33A. In this case, when the plate thickness ratio of the surfaces to be joined is three times or more, the protrusion 32d (33d) is provided on at least one of the flanges 32c and 33c.

  Next, the 2nd form of the gas cell 11g is demonstrated. In addition, the same number is attached | subjected and demonstrated to the component same as a 1st form.

  As shown in FIG. 11, the gas cell 11g of the second form uses the first body part 32A of the first form as it is, and the bottom part 33b side of the other second body part 33A is the bottom part 32b of the first body part 32A. In this configuration, a spacer member 34 is interposed between the facing flange portions 32c and 33c so as to overlap with each other. For this reason, the second main body portion 33A has an outer diameter that is at least smaller than the inner diameter of the opening portion 32a of the first main body portion 32A so as to enter the opening portion 32a of the first main body portion 32A. On the flange 33c of the second main body 33A, a similar protrusion 33d is formed along the outer periphery so as to face the protrusion 32d of the first main body 32A. The spacer member 34 interposed between the first main body portion 32A and the second main body portion 33A has a flat plate member as a base, and the diameters of the window portions 32e and 33e of the first main body portion 32A and the second main body portion 33A at the center. A through hole 34b having a larger diameter is formed. A cylindrical flange 34a is integrally formed on both surfaces of the outer peripheral edge portion of the spacer member 34 along the peripheral edge portion of the through hole 34b.

  And when manufacturing the gas cell 11g of the said 2nd form, it superposes | stacks the 1st main-body part 32A and the 2nd main-body part 33A, and it sets to the gas cell manufacturing jig 42 mentioned later with the spacer member 34 interposing. After sealing the target gas (the gas of the same type as the gas for detecting the gas concentration or the filling gas that does not react with the gas for detecting the gas concentration) in the openings 32a and 33a of the first main body portion 32A and the second main body portion 33A. The gas is hermetically sealed by resistance welding between the protrusions 32d and 33d of the flange portions 32c and 33c of the first main body portion 32A and the second main body portion 33A and the flat surface of the spacer member 34.

  In the gas cell 11g of the second form, the protrusion portions 32d and 33d having a mountain-shaped cross section are formed on the first main body portion 32A and the second main body portion 33A so as to contact with a predetermined resistance value so as to increase the resistance value of the joint surface. However, the protrusions may be formed on the spacer member 34 facing the flanges 32c and 33c. Further, the protrusions 32d and 33d are necessary when the thickness ratio of the surfaces to be joined is three times or more. Therefore, if the thickness ratio of the surfaces to be joined is less than three times, the protrusions 32d and 33d need not be formed.

  In the gas cell 11g of the second form, the flange 34a is provided on the spacer member 34. However, the flange 34a does not overlap the windows 32e and 33e, and the first main body 32A and the second main body 32a. What is necessary is just to provide in the position which can position 33A. Moreover, it is good also as a structure only of the 1st main-body part 32A and the 2nd main-body part 33A. In this case, when the plate thickness ratio of the surfaces to be joined is three times or more, the protrusion 32d (33d) is provided on at least one of the flanges 32c and 33c.

  Next, a third embodiment of the gas cell 11g will be described. In addition, the same number is attached | subjected and demonstrated to the component similar to a 1st form. As shown in FIG. 12, the gas cell 11g of the third form uses the first body part 32A of the first form as it is, and the other second body part 33B (33) is formed of a donut-shaped disk. . Therefore, the second main body portion 33B has a through hole 33f having a predetermined diameter at the center, and a window portion 33e is provided in the through hole 33f. Further, since the second main body portion 33B also functions as the spacer member 34 of the first form, a cylindrical flange having an outer diameter substantially the same as the diameter of the opening 32a of the first main body portion 32A on the flange 32g side. 33g is provided along the periphery of the through hole 33f. In addition, protrusions 32d and 33d are formed on the flange portion 32c and the second main body portion 33B of the first main body portion 32A so as to face each other.

  And when manufacturing the gas cell 11g of the said 3rd form, set the 1st main-body part 32A and the 2nd main-body part 33A in the gas cell manufacturing jig 42 mentioned later, and in the opening part 32a of 32 A of 1st main-body parts. After enclosing a target gas (filling gas that does not react with a gas of the same type as the gas concentration detection gas or a gas concentration detection), the protrusions of the flange portions 32c and 33c of the first main body portion 32A and the second main body portion 33A The gas is hermetically sealed by resistance welding between the portions 32d and 33d.

  In the gas cell 11g of the third form, the protrusions 32d and 33d having a mountain-shaped cross section are formed on the first main body 32A and the second main body 33B so as to contact with a predetermined resistance value so that the resistance value of the joint surface is increased. However, the spacer member 34 may be interposed between the first main body portion 32A and the second main body portion 33B, and a protrusion may be formed on at least one surface of the spacer member 34. Further, the protrusions 32d and 33d are necessary when the thickness ratio of the surfaces to be joined is three times or more. Therefore, if the thickness ratio of the surfaces to be joined is less than three times, the protrusions 32d and 33d need not be formed.

  Further, in the gas cell 11g of the third form, the flange 33g is provided outside the window portion 33e of the second main body portion 33A. However, the flange 33g does not overlap with the window portions 32e and 33e, and What is necessary is just to provide in the position positioned by the main-body part 32A. Moreover, the structure without the flange 33g may be sufficient.

  Next, the 4th form of the gas cell 11g is demonstrated. As shown in FIG. 13, the gas cell 11g of the fourth form is configured such that the first main body portion 32B (32) and the second main body portion 33B (33) form a donut-shaped disk. That is, through holes 32f and 33f having a predetermined diameter are formed in the centers of the first main body portion 32B and the second main body portion 33B, and window portions 32e and 33e are provided in the through holes 32f and 33f. Further, a cylindrical spacer member 34 is interposed between the first main body portion 32B and the second main body portion 33B. A through hole 34 b having a predetermined diameter is formed at the center of the spacer member 34. The diameter of the through hole 34b is at least equal to or larger than the diameters of the window portions 32e and 33e of the first main body portion 32B and the second main body portion 33B. Cylindrical flanges 32g and 33g are provided along the peripheral edge portions of the window portions 32e and 33e of the first main body portion 32B and the second main body portion 33B. Further, the first main body portion 32B and the second main body portion 33B are formed with protruding portions 32d and 33d facing each other.

  And when manufacturing the gas cell 11g of the said 4th form, the flanges 32g and 33g of the 1st main-body part 32B and the 2nd main-body part 33B face each other, and the spacer member 34 is interposed between them, and the gas cell manufacturing process mentioned later is carried out. The first main body portion is set after the target gas (filling gas that does not react with the gas of the same kind as the gas for detecting the gas concentration or the gas for detecting the gas concentration) is sealed in the through hole 34b of the spacer member 34. The gas is hermetically sealed by resistance welding between the protrusions 32d and 33d of the second body portion 33B and the flat surface of the spacer member 34.

  In the gas cell 11g of the fourth form, the first main body 32B and the second main body 33B have protrusions 32d and 33d having a mountain-shaped cross section so as to contact with a predetermined resistance value so that the resistance value of the joint surface is increased. Although the example which forms this was demonstrated, you may form a projection part in the plane of the spacer member 34 facing the 1st main-body part 32B and the 2nd main-body part 33B. The protrusions 32d and 33d are necessary when the thickness ratio of the surfaces to be joined is three times or more. Therefore, if the thickness ratio of the surfaces to be joined is less than three times, the protrusions 32d and 33d need not be formed.

  Further, in the gas cell 11g of the fourth embodiment, the flanges 32g and 33g are provided outside the window portions 32e and 33e of the first main body portion 32B and the second main body portion 33B, but the flanges 32g and 33g are provided with the window portion 32e. , 33e may be provided at a position that does not overlap with 33e and that is positioned in the through hole 34b of the spacer member 34. Moreover, the structure without the flanges 32g and 33g may be sufficient.

  Next, a fifth embodiment of the gas cell 11g will be described. As shown in FIG. 14, the gas cell 11g of the fifth form uses the first main body part 32A and the second main body part 33A of the first form, and a spacer member between the first main body part 32A and the second main body part 33A. 34 is interposed. That is, the openings 32a and 33a of the first main body 32A and the second main body portion 33A are opposed to each other, and the spacer member 34 formed in a cylindrical shape is interposed therebetween. A through hole 34 b having a predetermined diameter is formed in the central portion of the spacer member 34. The diameter of the through hole 34b is at least the same as or larger than the diameters of the windows 32e and 33e of the first main body 32A and the second main body 33A. Further, flanges 34a are provided on both surfaces of the spacer member 34 facing the first main body portion 32A and the second main body portion 33A along the peripheral edge portion of the through hole 34b. In addition, protrusions 32d and 33d are formed to face the flange portions 32c and 33c of the first main body portion 32A and the second main body portion 33A.

  And when manufacturing the gas cell 11g of the said 5th form, the gas cell manufacture mentioned later is made by facing the opening parts 32a and 33a of the 1st main-body part 32A and the 2nd main-body part 33A, and interposing the spacer member 34 between them. The target gas (the same type of gas or gas concentration as the gas for detecting the gas concentration) is set in the jig 42 and is inserted into the openings 32a and 33a of the first body portion 32A and the second body portion 33A and the through hole 34b of the spacer member 34. (Filling gas that does not react with the gas to be detected) is sealed, and resistance is generated between the protrusions 32d and 33d of the flange portions 32c and 33c of the first main body portion 32A and the second main body portion 33A and the flat surface of the spacer member 34. Weld and gas tightly seal.

  In the gas cell 11g of the fifth embodiment, the first main body 32A and the second main body 33A have protrusions 32d and 33d having a mountain-shaped cross section so as to contact with a predetermined resistance value so that the resistance value of the joint surface is increased. However, the protrusions may be formed on the plane of the spacer member 34 facing the first main body 32A and the second main body 33A. The protrusions 32d and 33d are necessary when the thickness ratio of the surfaces to be joined is three times or more. Therefore, if the thickness ratio of the surfaces to be joined is less than three times, the protrusions 32d and 33d need not be formed.

  Further, in the gas cell 11g of the fifth embodiment, the flange 34a is provided along the peripheral edge portion of the through hole 34b of the spacer member 34. However, the flange 34a does not overlap with the window portions 32e and 33e, and What is necessary is just to provide in the position positioned in the through-hole 34b of the spacer member 34. FIG. Moreover, the structure without the flange 34a may be sufficient.

  By the way, the gas cell 11g of each form mentioned above is not limited to the shape of the first main body portions 32A and 32B, the second main body portions 33A and 33B and the spacer member 34. You may form and form. Further, the shape of the protrusions 32d and 33d may be any shape that can increase the resistance as much as possible when contacting the joint surface and can be evenly joined when contacting.

  Each form of the gas cell 11g configured as described above is manufactured according to the procedure of the manufacturing process described below. Here, the case where the gas cell 11g of the first form is manufactured will be described as an example. First, a gas cell manufacturing apparatus used for manufacturing will be specifically described with reference to FIGS. 15 and 16.

  As shown in FIG. 15, the gas cell manufacturing apparatus 41 includes a gas cell manufacturing jig 42 that encloses gas in the openings 32a and 33a of the first main body portion 32A and the second main body portion 33A constituting the gas cell 11g and hermetically seals them. A power supply unit 43 that supplies driving power to the gas cell manufacturing jig 42, a gas cylinder 44 that contains a gas to be sealed in the gas cell 11g, and a vacuum pump 45 that evacuates the gas cell enclosure 51 during gas cell manufacturing. , A plurality of valves 46a, 46b, 46c, 46d for adjusting the flow rate of gas and air, a control unit 47 for controlling the opening and closing of each valve 46a, 46b, 46c, 46d, and the pressure value of the gas to be sealed and the vacuum state It consists of a pressure gauge 48 to measure.

  As shown in FIG. 16A, the gas cell manufacturing jig 42 includes a pair of first electrodes 49 and a first electrode 49 for joining the first main body portion 32A and the second main body portion 33A via the spacer member 34. The gas electrode enclosure 51 in which the two electrodes 50, the first electrode 49 and the second electrode 50 are detachably accommodated, and the first electrode 49 and the second electrode 50 are hermetically sealed. It is comprised with the sealing member 53. FIG.

  The pair of first electrode 49 and second electrode 50 has a cylindrical shape having a predetermined diameter, and the tip is formed in a substantially conical shape. The tip portions of the first electrode 49 and the second electrode 50 form a gas cell junction 52. The gas cell joint portion 52 includes concave portions 54a and 54b that match the shapes of the first main body portion 32A and the second main body portion 33A of the gas cell 11g to be manufactured. And after gas filling, the drive power supply is applied to the pair of first electrode 49 and second electrode 50 from the power supply unit 53, and the spacer member 34 is interposed between the first main body 32A and the second main body 33A. Resistance welding with.

  The gas cell enclosure 51 is made of an insulating member and is formed in a cylindrical shape having an inner diameter that is slightly larger than the outer diameter of each electrode 49, 50. In addition, a pipe 55 with a valve 46a is attached to the central portion of the gas cell enclosure 51 for use when the interior is evacuated or when gas is supplied to the interior. The valve 46 a is controlled to be opened and closed by the control unit 47 when adjusting the flow rate of the gas sealed in the gas cell sealing container 51 through the pipe 55 and maintaining a vacuum state.

  The sealing member 53 is provided to seal the inside of the gas cell enclosure 51 when the gas is sealed in the gas cell 11g to hermetically seal the gas cell 11g. The seal member 53 is formed of, for example, an O-ring, and is attached to each of the electrodes 49 and 50, for a total of four. Thereby, the parallelism between the electrodes 49 and 50 can be maintained. The first electrode 49 and the second electrode 50 can move in the gas cell enclosure 51 while keeping parallel, and the first electrode 49 and the concave portions 54a and 54b of the second electrode 50 are surely in contact with each other. 49 and the second electrode 50 are guided in the gas cell enclosure 51. The gas cell enclosure 51 has a structure that can be separated from the gas cell manufacturing apparatus 41.

Although the pressure gauge 48 depends on the performance of the vacuum pump 45, for example, measurement can be performed within a range of 1 × 10 ³ to 1 × 10 ⁵ Pa. The gas cylinder 44 is equipped with a decompressor. For example, when the dilution gas is helium, a helium leak detector can be used for the gas leak inspection. The vacuum pump 45 is desirably oil-free as much as possible.

  And when manufacturing the gas cell 11g, first, each electrode 49 and 50 is wiped off dirt etc. using alcohol etc. In particular, it is preferable that the portions (joint surfaces) where the flange portions 32c and 33c of the first main body portion 32A and the second main body portion 33A are in contact with the spacer member 34 are intensively wiped off. Then, as shown in the enlarged view of the gas cell joint portion 52 in FIG. 16B, the first electrode 49 is disposed in the gas cell enclosure 51 so that the concave portion 54a faces upward. Next, the first main body portion 32A is set in the concave portion 54a of the arranged first electrode 49. Subsequently, the spacer member 34 is set on the first main body portion 32A. Next, the second electrode 50 is set in the recess 54b, and the second electrode 50 is set in the gas cell enclosure 51 so that the recess 54b faces downward (on the spacer member 34 side). As described above, in the gas cell enclosure 51, the components constituting the gas cell 11g, that is, the first main body 32A, the spacer member 34, and the second main body 33A are set in the recesses 54a and 54b of the electrodes 49 and 50. The gas cell manufacturing apparatus 41 performs operations such as gas sealing.

  Next, as a manufacturing method of the gas cell 11g of each form described above, the gas cell 11g of the first form will be described as an example with reference to the flowchart shown in FIG.

  First, when manufacturing the gas cell 11g, the first main body portion 32A, the second main body portion 33A, and the spacer member 34 interposed between the main body portions 32A and 33A are set in the gas cell enclosure 51. And the gas cell enclosure 51 is connected to the gas cell manufacturing apparatus 41 (ST1). Next, all valves are opened with the main plug of the gas cylinder 44 closed (ST2). With all the valves open, the power switch of the vacuum pump 45 is turned on (ST3).

  When the power source of the vacuum pump 45 is turned on, the air in the gas enclosure 51 is drawn and a vacuum state is established. In order to measure this state, the pressure gauge 48 is used to confirm whether the internal pressure in the gas cell enclosure 51 is stable (ST4). When it is confirmed that the gas cell enclosure 51 is in a vacuum state and the internal pressure in the gas cell enclosure 51 is stabilized (ST4-Yes), the valves 46b, 46c, and 46d are closed (ST5). On the other hand, when the inside of the gas enclosure 51 is not in a vacuum state or when the vacuum state is unstable (ST4-No), some abnormality has occurred in the gas cell enclosure 51 itself or attached to the electrodes 49, 50. Since the sealing member 53 is not functioning properly, the gas cell enclosure 51 and the sealing member 53 are inspected again, and then reconnected to the gas cell manufacturing apparatus 41 to return to ST1.

  After the valves 46b, 46c, 46d are closed in ST5, it is confirmed again whether the pressure value of the pressure gauge 48 is stable (ST6). At this time, the numerical value change of the pressure gauge becomes a standard for which about several tens of Pa is stable for several seconds, but when stable (ST6-Yes), the valve 46b and the valve 46d are opened and evacuation is again performed ( ST7). On the other hand, if the pressure gauge 48 is not stable at the time of confirmation of ST6 (ST6-No), there is some abnormality in the gas cell enclosure 51 itself, or the seal member 53 attached to each electrode 49, 50 is normal. Therefore, after returning to ST1, the gas cell enclosure 51 and the seal member 53 are inspected again, and then reconnected to the gas cell manufacturing apparatus 41 and returned to ST1. After evacuation, the valve 46d is closed, the valve 46c and the main plug of the gas cylinder 44 are opened and closed, and the value of the pressure gauge 48 is adjusted to a specified pressure (ST8).

  It is confirmed whether or not the pressure has been adjusted to the specified pressure (ST9), and when the pressure adjustment is completed (ST9-Yes), the gas cell enclosure 51 is separated from the gas cell manufacturing apparatus 41 (ST10). On the other hand, when the pressure cannot be adjusted (ST9-No), the process returns to ST7 and evacuation is performed again. The gas cell enclosure 51 separated from the gas cell manufacturing apparatus 41 is set in a resistance welding machine (not shown) and resistance welding is performed (ST11) to manufacture the gas cell.

  Next, the process of inspecting whether the gas cell 11g functions normally will be described with reference to the flowchart shown in FIG.

  When the gas cell 11g is manufactured through the manufacturing process shown in FIG. 17, light that emits a wavelength absorbed by the gas in the gas cell 11g is transmitted, and the presence or absence of gas is checked by checking the absorption waveform of the light (ST21). ). It is determined whether or not there is a gas absorption waveform (ST22). If it is determined that there is gas (ST22-Yes), a gas cell is set in a container that can be evacuated, evacuated, and stored for 24 hours. (ST24). On the other hand, when there is no gas absorption waveform (ST22-No), it is treated as a defective product (ST23).

  After the step ST24, when the dilution gas is helium, a leak test is performed with a helium leak detector to inspect the gas leak (ST25). If it is determined that there is no leak as a result of the leak test (ST26-No), the emission light is transmitted through the wavelength absorbed by the gas in the gas cell 11g, and the presence or absence of gas is checked by checking the absorption waveform of the light. (ST28). On the other hand, if it is determined that there is a leak (ST26-Yes), it is processed as a defective product (ST27). If there is an absorption waveform of light absorbed by the gas in the gas cell in the inspection of ST28 (ST29-Yes), it is determined that the gas cell functions normally, and the inspection ends. On the other hand, when there is no gas absorption waveform (ST29-No), it is treated as a defective product (ST30).

  In addition, about the process of ST24 mentioned above, you may abbreviate | omit and may transfer to the process of ST25 after the process of ST22.

  The gas cell 11g manufactured as described above is housed in the butterfly-type case body 11a of the semiconductor laser module 11 together with other components and hermetically sealed. The semiconductor laser module 11 is incorporated into the semiconductor unit 4.

  Thus, in this example, the gas cell 11g is manufactured using a metal container (the 1st main-body part 32, the 2nd main-body part 33). Thereby, there is no fluctuation | variation of the gas concentration inside a container by generation | occurrence | production of the gas which arises at the time of welding, or a heat | fever, and a highly reliable gas cell can be manufactured small. In addition, since the gas cell is manufactured using a container manufactured by mechanical processing, the dimensional accuracy is high and the mounting density can be improved.

  In addition, by selecting, for example, diluted helium as a filling gas that does not react with the gas whose concentration is to be detected, the gas cell after welding can be easily subjected to a gas tightness test with a helium leak detector, and the reliability in terms of air density is also improved. Gas cell with high height can be manufactured.

  The semiconductor laser module 11 having the gas cell 11g manufactured as described above is hermetically sealed by accommodating the gas cell 11g together with other components in the butterfly-type case body 11a. Ambient influences such as outside temperature can be prevented.

  Furthermore, since the gas cell 11g is accommodated in the butterfly case body 11a of the semiconductor laser module 11, a sufficient amount of light can be received by the light receiver 11h without a lens for condensing the backward emission light from the semiconductor laser 11c. it can. In addition, since it is not necessary to mount a lens, the influence of return light due to the emission of laser light from the semiconductor laser 11h is reduced, and an optical isolator is mounted on the optical path between the semiconductor laser 11c and the light receiver 11h. Even if it is not, there is no problem in practical use. Furthermore, since each component including the gas cell 11g is accommodated in the small butterfly-type case body 11a to configure the semiconductor laser module 11, the heat capacity is reduced, and even when the semiconductor laser module 11 is started to be driven from a low temperature, An operating temperature can be stabilized in a short time, and a gas concentration detection device with better operability can be provided.

  By the way, helium gas is given as an example of the dilution gas to be sealed in the gas cell. However, the present invention is not limited to this, but according to the gas to be detected by the gas concentration measuring device, for example, it is sealed in a gas cell such as hydrocarbon such as methane or oxygen dioxide The gas can be freely selected and used according to the gas to be detected.

  When the gas concentration is measured by the gas concentration measuring device 1 incorporating the semiconductor laser unit 4 including the small and light semiconductor laser module 11, the holding portion 6 of the main body 5 is held and the window portion 8 is directed to the measurement atmosphere. And press the start button 6a. As a result, the power is turned on, and laser light is emitted as measurement light from the semiconductor laser 11 c in the semiconductor laser module 11. The measurement light is reflected by the reflection mirror 21 toward the dichroic mirror 22, and is combined with the guide light from the laser pointer 12 by the dichroic mirror 22 and emitted from the window 8 of the main body 5 toward the measurement atmosphere. Then, the light reflected through the measurement atmosphere of the measurement target gas as the measurement light is emitted is collected by the condenser lens 7 of the main body 5 and received and detected by the light receiver 9 in the main body 5. The electrical signal detected and received by the light receiver 9 is amplified with a predetermined amplification degree by the measurement light amplifier 3a and then input to the received light signal detector 3b. The measurement light amplifier 3a amplifies the input signal so that the 1f signal and the 2f signal have the same detection level within the measurement target gas concentration range. The received light signal detection unit 3b detects 1f and 2f from the input signal and inputs the detected signals to the calculation unit 3c. The calculation unit 3c calculates the gas concentration of the measurement target gas based on the ratio (2f / 1f) of 1f and 2f input from the received light signal detection unit 3b.

  As described above, in this example, the measurement light for measuring the concentration of the measurement target gas and the guide light for confirming the emission position of the measurement light are emitted substantially on the same axis. The position can be accurately confirmed by the guide light, the optical portion can be easily directed toward the measurement location, and the measurement light can be emitted, and the gas concentration at the fine measurement location can be accurately measured.

  Further, for example, if the configuration shown in FIGS. 6 and 7 is adopted and the optical axis adjustment mechanism unit 17 is provided, the emission direction of the measurement light reflected by the reflection mirror 21 can be finely adjusted.

  Furthermore, if a plurality of semiconductor laser modules 11 that emit measurement light having different wavelengths are prepared and the configuration shown in FIGS. 8 and 9 is adopted, for example, a plurality of types of gas concentrations can be measured once without increasing the size of the apparatus. Can be done.

  The semiconductor laser module 11 incorporated in the semiconductor laser unit 4 can be miniaturized by a configuration in which each component including the ultra-small gas cell 11g is accommodated in the butterfly case body 11a of the semiconductor laser module 11 and sealed. .

  Since the semiconductor laser unit 4 that has been reduced in size is incorporated in the main body 5 and no optical fiber is used when the measurement light from the semiconductor laser 11c is guided to the window portion 8, the measurement light can be measured without causing any loss. It is possible to emit light toward the center and to perform stable and accurate measurement. In addition, the miniaturized semiconductor laser module 11 is arranged on the outer peripheral wall of the main body 5, the measurement light from the semiconductor laser 11 c is reflected by the reflection mirror 21, and guided to the window portion 8 of the main body 5 together with the guide light by the dichroic mirror 22. Since it is a structure, there are few things which become obstructive when condensing measurement reflected light with the condensing lens 7, it can light-receive the measurement reflected light from measurement atmosphere with sufficient light reception amount, and can prevent the fall of measurement accuracy.

  As shown in FIG. 2, a circuit configuring a circuit for stabilizing the temperature of the semiconductor laser 11 g of the semiconductor laser unit 11 and a measuring unit 3 for performing signal processing of reflected measurement light at the back of the opening 5 a of the main body 5. Can be arranged together.

  Conventionally, since it was difficult to manufacture the gas cell in an ultra-small size, the gas cell and the light receiver were arranged outside the semiconductor laser module. However, in the gas concentration measuring apparatus 1 of this example, the gas cell 11g was accommodated. The semiconductor laser unit 4 in which the semiconductor laser module 11 is incorporated is employed. That is, the semiconductor laser module 11 employed in the present example has a configuration in which the ultra-small gas cell 11g is accommodated in the butterfly type case body 31a, whereby the semiconductor laser module 11 can be reduced in size. In addition, since the gas cell 11g is mounted inside the butterfly-type case body 11a, a sufficient amount of light can be received by the light receiver 11h even without a lens for condensing the emitted light from the semiconductor laser 11c. In addition, since it is not necessary to mount a condensing lens, the influence of return light is reduced, and even if an isolator is not mounted, there is no problem in practical use.

  By the way, in the form mentioned above, it is set as the structure which integrates the measurement part 3 in the opening 5a back part of the main body 5 of the optical part 2, but between this measurement part 3 and the measurement part 101 shown in FIG. 21 conventionally well-known. Are wired and connected, and the measurement result by the measurement unit 3 is transmitted to the measurement unit 101 having the display function shown in FIG. 21, the detailed measurement result can be visually confirmed.

It is a front view of the gas concentration measuring apparatus containing the semiconductor laser unit which concerns on this invention. It is a side view of the gas concentration measuring apparatus of FIG. It is a front view which shows an example of the semiconductor laser unit employ | adopted as the gas concentration measuring apparatus which concerns on this invention. FIG. 4 is a side view of the semiconductor laser unit of FIG. 3. It is a plane sectional view of a semiconductor laser module which constitutes a part of a semiconductor laser unit concerning the present invention. It is a top view which shows an example of the optical axis adjustment mechanism of the semiconductor laser unit which concerns on this invention. It is a side view of the optical axis adjustment mechanism of FIG. It is a side view which shows the other structural example of the semiconductor laser unit employ | adopted as the gas concentration measuring apparatus which concerns on this invention. It is a side view which shows the other structural example of the semiconductor laser unit employ | adopted as the gas concentration measuring apparatus which concerns on this invention. It is sectional drawing which shows the 1st form of a gas cell. It is sectional drawing which shows the 2nd form of a gas cell. It is sectional drawing which shows the 3rd form of a gas cell. It is sectional drawing which shows the 4th form of a gas cell. It is sectional drawing which shows the 5th form of a gas cell. It is the schematic which shows schematic structure of a gas cell manufacturing apparatus. (A) It is sectional drawing of a gas cell enclosure. (B) It is a fragmentary sectional view which shows the state which set the main-body part which comprises a gas cell in a gas cell junction part. It is a flowchart figure which shows the process of manufacturing a gas cell using a gas cell manufacturing apparatus. It is a flowchart figure which shows the process of test | inspecting the manufactured gas cell. It is a front view which shows an example of the optical part of the conventional reflective gas concentration measuring apparatus. It is a side view of the optical part of FIG. It is a figure which shows an example of the measurement part of the conventional reflection type gas concentration measuring apparatus. It is a figure which shows an example of the light source unit incorporated in the measurement part of FIG. It is a front view which shows the other example of the optical part of the conventional reflection type gas concentration measuring apparatus. It is a side view of the optical part of FIG. It is a figure which shows an example of the light source unit integrated in the optical part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas concentration measuring device 2 Optical part 3 Measuring part 3a Measurement light amplification part 3b Light reception signal detection part 3c Operation part 3d Wavelength stabilization circuit 4 Semiconductor laser unit 5 Main body 5a Aperture 6 Grasping part 7 Condensing lens (condensing means)
DESCRIPTION OF SYMBOLS 8 Window part 9 Light receiver 11 Semiconductor laser module 11a Butterfly type | mold case main body 11b Output window 11c Semiconductor laser 11d Collimating lens 11e Optical isolator 11f Peltier element (temperature control element)
11g Gas cell 11h Photodiode (receiver)
11i thermistor (temperature measuring element)
DESCRIPTION OF SYMBOLS 12 Laser pointer 12a Main body 12b Semiconductor laser 13 Multiplexing / demultiplexing means 14 Support member 15 Insulating member 16 (16A, 16B) Radiator 17 Optical axis adjustment mechanism part 21 Reflection mirror 22 Dichroic mirror 23 Mounting part 23a Recessed part 24 Adjustment arm 24a Tip part 25 Fixing screw 26 Adjustment screw 26a Tip 27 Beam splitter 28 Mounting plate 29 Heat conductor 32 (32A, 32B) First main body 33 (33A, 33B) Second main body 32a, 33a Opening 32b, 33b Bottom 32c, 33c Gutter part 32d, 33d Protrusion part 32e, 33e Window part 32f, 33f Through hole 32g, 33g Flange 34 Spacer member 34a Flange 34b Through hole 41 Gas cell manufacturing apparatus 42 Gas cell jig 43 Power supply part 44 Gas cylinder 45 Vacuum pump 46a, 4 b, 46c, 46d Valve 47 Control part 48 Pressure gauge 49 First electrode 50 Second electrode 51 Gas cell enclosure 52 Gas cell joint part 53 Seal member 54a, 54b Recessed part 55 Piping 100 Optical part 101 Measuring part 102 Light source unit 103 Optical fiber 104 Main body 104a Opening 105 Gripping part 106 Condensing lens 107 Emission part 108 Light receiver 109 Laser pointer 110 Case main body 111 Semiconductor laser module 112 Reference gas cell 113 Photo detector 114 Case 115 Connector 116 Cooling fin 117 Temperature control element 200 Optical part 300 Light source Unit 301 Protective glass 302 Cylindrical case 303 Semiconductor laser 304 Substrate 305 Base 306 Temperature control element 307 (307a, 307b, 307c) Aspheric lens 30 Mount 309a, 309b optical isolator 310 reference gas cell 311 photo detector L-L central axis

Claims (6)

The semiconductor laser (11c) emits measurement light frequency-stabilized by a gas absorption line to the measurement atmosphere, and receives the reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted. And detecting a fundamental wave phase sensitive detection signal and a double wave phase sensitive detection signal of the modulation frequency of the semiconductor laser from the output signal of the light receiver, and the gas concentration of the measurement atmosphere based on the ratio of both signals A semiconductor laser unit (4) used in a gas concentration measuring device (1) for measuring
A semiconductor laser module (11) comprising a gas cell filled with the same type of gas as the semiconductor laser and the concentration measurement target gas, and emitting the measurement light;
A laser pointer (12) for emitting visible light as guide light for guiding the measurement light to the measurement atmosphere;
A semiconductor laser unit comprising: a multiplexing / demultiplexing means (13) for multiplexing the measurement light and the guide light substantially coaxially. The multiplexing / demultiplexing means (13) includes a reflection mirror (21) that reflects the measurement light, and a dichroic mirror (22) that multiplexes the measurement light reflected by the reflection mirror and the guide light substantially coaxially. The semiconductor laser unit according to claim 1, further comprising: The semiconductor laser unit according to claim 2, further comprising an optical axis adjusting mechanism (17) for adjusting an emission direction of the measuring light reflected by the reflecting mirror (21). The semiconductor laser (11c) emits measurement light frequency-stabilized by a gas absorption line to the measurement atmosphere, and receives the reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted. And detecting a fundamental wave phase sensitive detection signal and a double wave phase sensitive detection signal of the modulation frequency of the semiconductor laser from the output signal of the light receiver, and the gas concentration of the measurement atmosphere based on the ratio of both signals A semiconductor laser unit (4) used in a gas concentration measuring device (1) for measuring
A plurality of semiconductor laser modules (11), each comprising a gas cell filled with the same type of gas as the semiconductor laser and the concentration measurement target gas, and emitting laser beams of different wavelengths corresponding to gas absorption lines as the respective measurement beams;
As a guide light for guiding each measurement light to the measurement atmosphere, a laser pointer (12) that emits visible light;
A multiplexing / demultiplexing means (13) including a reflection mirror (21) for reflecting predetermined measurement light among the plurality of measurement lights, wherein the predetermined measurement light and the plurality of measurement lights And a multiplexing / demultiplexing means (13) for multiplexing measurement light other than the predetermined measurement light substantially coaxially, and for multiplexing the predetermined measurement light and the visible light substantially coaxially. A featured semiconductor laser unit. The semiconductor laser module (11) includes the semiconductor laser (11c),
A collimating lens (11d) for converting measurement light emitted from the semiconductor laser into parallel light;
An optical isolator (11e) for suppressing return of reflected light to the semiconductor laser;
A temperature measuring element (11i) for measuring the temperature of the semiconductor laser;
A temperature control element (11f) for controlling the temperature of the semiconductor laser;
The gas cell (11 g);
The light receiver (11h) for receiving laser light emitted backward from the semiconductor laser after passing through the gas cell is built in a butterfly case (11a) and hermetically sealed. The semiconductor laser unit described. A tubular body (5) having a bottom;
A semiconductor laser unit (4) according to any one of claims 1 to 5;
A light receiver disposed in the main body (5) and in the vicinity of the central axis (LL) of the main body;
Condensing means (7) which is installed in the opening (5a) of the main body and receives the reflected measurement light reflected from the measurement atmosphere as the measurement light is emitted from the semiconductor laser unit and collects it on the light receiver. A condensing means (7) having a window (8) for allowing the measurement light and guide light from the laser pointer (12) to pass in the vicinity of the central axis of the condensing means;
Measuring units (3a, 3b, 3c) that convert the reflected measurement light collected by the light collecting means and received by the light receiver into an electric signal, and calculate a gas concentration based on the electric signal; A gas concentration measuring device integrally provided in the main body.

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