JPS5895226A - Temperature detector and temperature measuring device - Google Patents

Abstract

PURPOSE:To obtain a temperature detector and a temperature measuring device where electric circuits are not included in measuring parts and signal transmitting parts, by using a hetero junction element which consists of conductors different in forbidden band width, an optical waveguide which transmits and receives the light to and from this element, etc. CONSTITUTION:A hetero junction element 20 consists of many layers of an absorption light emitting layer 22 and a clad layer 23, which are laminated on a semiconductor substrate 21, and reflection preventing films 25 and 24 on both faces and is excited by the light of a laser light source from an optical fiber 10. Then, the light of a required wavelength different in forbidden band width is generated from the layer 22 in accordance with the temperature of the layer 22. The light of the light source including this generated light is propagated through the fiber 10, and the light of the light source is eliminated in an optical filter. Short-wavelength components and long- wavelength components are separated from each other in an optical filter, and these components are subjected to processings such as the operation of an intensity ratio of both lights of separated wavelength components or the like, and the temperature of the layer 22 is measured. Consequently, the temperature detector and the temperature measuring devices which do not include electric circuits in measuring parts and signal transmitting parts and are not affected by noise or the like are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature detection element capable of optically measuring temperature and a temperature measurement device using the same.

It goes without saying that temperature detection elements or temperature measurement devices are widely used and play an important role as means for process control and equipment monitoring. However, most of the conventional temperature measuring means, especially those that can be determined remotely, utilize thermoelectric conversion elements. Conventional devices have the disadvantage that they cannot be used in environments where electrical spinning is highly disturbed or in high-voltage equipment.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a temperature sensing element and a temperature measuring device that do not include electrical circuits in the foot part and the signal transmission part.

According to the present invention, a heterojunction element comprising a multilayer structure of semiconductors having different forbidden band widths introduces light into the heterojunction element,
and a temperature detection element coupled with an optical waveguide that guides the light emitted from the heterojunction element, and a temperature measurement device using the same, that is, a heterojunction element consisting of a multilayer structure of semiconductors with different forbidden band widths. a light source having a wavelength shorter than the absorption edge wavelength of the semiconductor having the smallest forbidden band width constituting the heterojunction element; an optical fiber that guides the light from the skeleton light source to the heterojunction element; A temperature measuring device includes a filter that separates the light emitted from the junction element into two components, a short wavelength side and a long wavelength side, and a circuit that detects the intensity of the two separated light components and calculates the ratio. can get.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the temperature detection element of the present invention. In this example, the diameter is 100 μm and the numerical aperture NA is 0.
．． Optical fiber 1 with an outer diameter of 125 μm and a core 10c of 2
It is composed of a heterojunction element 20 provided at the tip of 0. The heterojunction element 20 is epitaxially grown on a semiconductor substrate 21 made of lnP single crystal to a thickness of 2.
μm I no, 68 (JB 0.32A@O, 1B
ll Po, sx (absorption edge wavelength λy ~ 1.4 μm)
The absorbing/emitting layer 22 consists of a 1 μm thick lnP (1
The surface of the cladding layer 23 and the back side of the surface-polished semiconductor substrate 21 are provided with anti-reflection coatings for the excitation light introduced from the optical fiber 10. Membranes 24 and 25 are applied.

The area of the heterojunction element 20 that operates as a temperature detection section is about 300 μm square, and the thickness is about 100 μm.

As excitation light, the absorption edge wavelength of the absorption light emitting layer 22 is shorter than 1.4 μm and the absorption edge wavelength of the cladding layer 23 and semiconductor substrate 21 is longer than 0.95 μm, for example, 1.0 μm of a YAG laser.
6 μm wavelength light or 1.2 to 1.3 of Hiro semiconductor laser
When light with a wavelength of .mu.m is used as excitation light and is introduced through the optical fiber 10 to irradiate the heterojunction element 20, the excitation light is absorbed by the absorption/emission layer 22 and optically excites the absorption/emission layer 22. The optically excited absorption/emission layer 22 emits light with a wavelength corresponding to its forbidden band width.

This emission wavelength is determined by the temperature of the absorption/emission layer 22 as a value specific to the material. In this embodiment, the central value of the emission wavelength changes at a rate of about 5 A (shifting to the longer wavelength side with respect to temperature rise) per temperature change of 1°C. Therefore, optical fiber 1
By measuring the center wavelength of the light emitting component that has returned to 0, the absolute temperature of the area in contact with the heterojunction element 20 can be determined purely optically. In this embodiment, the heterojunction element 20 that operates as a temperature detection section is extremely small.
Also, since the thermal resistance of the optical fiber 10 as a signal transmission part is high, there is little disturbance to the measurement target and accurate measurement is possible.In addition, in the above-mentioned embodiment, the reflected component of the excitation light does not interfere with the measurement. However, in order to use an excitation light removal filter in the wavelength measurement part, the anti-reflection films 24 and 25 are attached to the tip of the spacing 10 and the heterojunction element 20 is made of transparent resin. They may be fixed together and integrated. Note that although an In)'-1nGaAsP-based semiconductor was used in the above embodiment, the present invention is not necessarily limited to this. Any material that exhibits photoexcited luminescence may be used, but in consideration of luminous efficiency, a double-electrode transition type semiconductor is preferred, and a double heterojunction structure is preferred over a single heterojunction structure.

FIG. 2 is a block diagram of one embodiment of the temperature measuring device of the present invention. In this embodiment, the drive circuit 111 drives the wavelength 1.
．． Semiconductor laser 101 that emits pulses at 2 μm, lens 102 for laser/7-eyeper coupling, long wavelength reflection filter 103 that transmits 1.2 μm, optical fiber 10, heterojunction element 20 with emitted wave length of 1.4 μm, excitation light removal Filter 106. A long/short wavelength component separation filter 107 with a boundary wavelength of 1.4 μm, a long wavelength component intensity detection unit 108,
It is composed of a short wavelength component intensity detection section 109 and a calculation section 110 that calculates the ratio of the output signals of these two detection sections. When the heterojunction element 20 is brought into contact with the object to be measured, the ratio of the long wavelength component and the short wavelength component of the emitted light changes depending on the temperature, and the temperature signal of the object to be measured is extracted as the output signal of the calculation section 110. That is, when the temperature is high, the long wavelength component is large, and when the temperature is low, the short wavelength component is large. Since the calculation unit 110 calculates the ratio of both signals, measurement errors do not occur due to changes in excitation light intensity or light emission efficiency. In addition, according to this embodiment, the heterojunction element 20'1r, which has a small heat capacity, is used as a temperature detection section, and the response speed determined by the lifetime of the photoexcited electron-hole pair is also 01.
Since it is extremely fast at less than μS, measurements with good time response are possible. Of course, since the measurement and signal transmission is based on light, there is no electrical induction interference, and safe measurements can be made even in high-voltage areas.

By the way, in the above embodiment, a semiconductor laser was used as the excitation light source, but the invention is not necessarily limited to this, and other lasers such as a YAG laser or a discharge tube may be used. Further, the light source does not need to be a pulsed light source and may emit light continuously. In the above-described embodiment, it is also effective to apply the signal from the drive circuit 111 to the long wavelength component intensity detection section 108 and the short wavelength component intensity detection section 109 to perform synchronous detection.

Finally, to summarize the effects of the present invention, it is possible to obtain a temperature detection element and device that are free from electrical induction disturbances, high voltage electric shocks, etc., and are capable of measuring temperature with good time responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the temperature detection element of the invention, and FIG. 2 is a configuration diagram of an embodiment of the temperature measurement device of the invention. In the figure, 10.)...Optical fiber, 10C...
・Core, 20... Heterojunction element, 21...
... Semiconductor substrate, 22 ... Absorption/emission layer, 23
... Cladding layer, 24 and 25 ... Antireflection film, 101 ... Semiconductor laser, 102.
... Lens, 103 ... Long wavelength reflection filter, 106 ... Excitation light removal filter, 107
...Long and short wavelength component separation filter, 108...
... Long wavelength component intensity detection section, 109 ... Short wavelength component intensity detection section, 110 ... Calculation section, 11
1... Drive circuit.

Claims (1)

[Claims] 1. A heterojunction element made of a multilayer structure of semiconductors with different forbidden band widths is coupled to an optical waveguide that introduces light into the heterojunction element and guides light emitted from the heterojunction element. Temperature sensing element made of Z: a heterojunction element consisting of a multilayer structure of semiconductors with different forbidden band widths; a light source having a wavelength shorter than the absorption edge wavelength of the semiconductor with the smallest forbidden band width constituting the heterojunction element; an optical fiber blind bar that guides the light from the heterojunction element to the heterojunction element; a filter that separates the light emitted from the heterojunction element into two components, one on the short wavelength side and the other on the long pitch side; A temperature measuring device comprising a circuit for detecting the intensities of two light components and calculating the ratio thereof.