JPS63234123A - Optical temperature measuring instrument - Google Patents

Abstract

PURPOSE:To take a measurement of temperature with high sensitivity by projecting and photodetecting light on an interference filter as a temperature sensing part through an optical fiber, photodetecting light from the optical fiber, and measuring the temperature by a measuring means. CONSTITUTION:Light from a light source 1 such as an incandescent lamp is projected on the multilayered interference film filter 3 as the temperature sensing part through the optical fiber 21. The light transmitted through the filter 3 becomes band-pass transmitted light with center wavelength shown by A and is incident on a detector 5 through an optical fiber 22 and a filter 4. The output of the detector 5 is processed by the measuring means 6 to measure the temperature. The filter 3 shifts in transmission wavelength characteristics to the long-wavelength side from A to A' as temperature T rises, but the filter 4 does not vary in wavelength characteristics and has long-pass characteristics shown by B, so the degree of the overlap between A; and B varies with the temperature T and radiant energy incident on the detector 5 varies. The measuring means 6 measures the temperature T from the output of the detector 5 by an arithmetic expression, etc., found previously by experiment, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical temperature measuring device using an optical fiber.

[Conventional technology] Conventionally, a semiconductor or the like whose transmittance changes depending on temperature is used as a temperature sensing part, light is emitted and received by an optical fiber, and the temperature is measured from the change in the amount of light received by a detector. There is.

[Problems that this invention attempts to solve] However,
When a semiconductor or the like is used as the temperature-sensing section, the characteristics such as transmittance are determined by the properties of the material, and there are problems such as difficulty in freely selecting the temperature measurement range and sensitivity as required.

In view of the above points, an object of the present invention is to provide an optical temperature measuring device that uses an interference film filter as a temperature sensing section and enables highly sensitive temperature measurement.

[Means for Solving the Problems] The present invention projects and receives light through an optical fiber to an interference film filter as a temperature sensing part whose transmittance or warp ratio changes depending on temperature, This is an optical humidity measuring device that receives light with a detector and measures temperature with a measuring means.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

In the figure, light from a light source 1 such as an incandescent lamp, a halogen lamp, or an LED is projected through an optical fiber 21 to a multilayer interference film filter 3 serving as a temperature sensing section. The light transmitted through the interference film filter 3 such as this bandpass filter is
The light is converted into a band-pass transmitted light having a center wavelength as shown in FIG. The output of the detector 5 is suitably processed by the measuring means 6]E
The temperature is measured.

In other words, when the temperature T rises, the interference film filter 3
The transmission wavelength characteristic shifts to the longer wavelength side from Fig. 2 to A', and the wavelength characteristic of the filter 4 in front of the detector 5 remains unchanged as a long pass (low pass) characteristic as shown in Fig. 2B. The degree to which Δ or 8- and 8 hang changes depending on the temperature T, and the radiant energy incident on the detector 5 changes.

From the output of the detector 5, the temperature T is measured by the measuring means 6 from the performance surface, table, etc., which have been determined in advance through experiments, total time t1, etc.

For the interference film filter 3, use 81 or Ge for the high refractive index film, SiO, etc. for the low refractive index film, form a multilayer film by 'iA deposition, etc., and adjust the desired transmission according to the temperature measurement range and sensitivity. The filter has wavelength characteristics.

In this way, by changing the number of layers and film configuration of a multilayer interference film filter, a filter with the required bandpass characteristics can be obtained (warped), and the temperature coefficient of the refractive index of 3i and Qe is approximately 1.5X10-'/'℃, which is sufficiently large that it can be used as a temperature sensing section.

FIG. 3 shows another embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate equivalent components.

The light from the light source 1 passes through the half mirror 7 and is projected onto the interference film filter 3 as a temperature sensing section by the optical fiber 2.
The reflected light is again taken out via the optical fiber 2, reflected by the half mirror 7, transmitted through the filter 4, and incident on the detector 5.

In this case, the wavelength characteristics of the reflected light from the interference film filter 3 change depending on the temperature T as shown in FIG. 4A', but the wavelength characteristics of the filter 4 do not change as shown in FIG. 4B.
The degree of overlap between A or A' and B changes depending on the temperature T, and the radiant energy incident on the detector 5 changes. From the output of the detector 5, the temperature T is measured by the measuring means 6 using a calculation formula, table, etc., calculated in advance.

As shown in FIG. 5, by forming an interference film filter 3 on the end face of the optical fiber 20 by vapor deposition or the like (for example, by forming interference film filters on the end faces of a large number of optical fibers at the same time), a uniform The temperature sensing part can be produced inexpensively and quickly, has compatibility, and can be attached to and detached from the optical fiber 2 using the optical connector 20a, making it easy to handle,
Maintenance, etc. becomes easier.

[Effects of the Invention] As described above, this invention uses an interference film filter as a temperature sensing section, so it becomes possible to easily measure humidity using an optical fiber. The transmission wavelength characteristics and the like can be freely changed by changing the film configuration, etc., and it is possible to easily measure the temperature at each level according to the temperature measurement range, sensitivity, etc.

[Brief explanation of the drawing]

FIGS. 1, 3, and 5 are diagrams for explaining the configuration of an embodiment of the present invention, and FIGS. 2 and 4 are diagrams for explaining wavelength characteristics. 1... Light source, 2.20.21.22... Optical fiber, 3... Interference film filter (temperature sensitive part), 4... Filter, 5... Detector, 6... Measurement Means, 7... Half mirror 120a... Optical connector Showa Year Month Date 1, 1 display 1988 Patent application No. 68-493 @ 2 Name of the invention Optical temperature measuring device 3 Person making the correction Relationship to the incident Patent applicant address 1-26-2-3 Nishikiranjuku, Shinjuku-ku, Tokyo
and filter 4 may be used interchangeably. ”
Insert.

Claims (1)

[Claims] 1. An interference film filter as a temperature-sensitive part whose transmittance or reflectance changes depending on temperature, and light from a light source projected onto this interference film filter and transmitted or reflected by the interference film filter. What is claimed is: 1. An optical measuring device comprising: an optical fiber for extracting light; a detector for receiving light from the optical fiber; and a measuring means for measuring temperature from the output of the detector. 2. The optical temperature measuring device according to claim 1, wherein the detector receives light from an optical fiber through a filter. 3. The optical temperature measuring device according to claim 1 or 2, characterized in that an interference film filter is formed on the end face of the optical fiber. 4. The optical temperature sensor according to claims 1 to 3, characterized in that the temperature sensing section including an optical fiber having an interference film filter formed on the end surface is detachable from the optical fiber using an optical connector. measuring device. 5. Si or Ge as a high refractive index film of the interference film filter
An optical temperature measuring device according to any one of claims 1 to 4, characterized in that the optical temperature measuring device uses: 6. The optical temperature measuring device according to claims 1 to 5, characterized in that the film configuration or the number of layers of the interference film filter is changed depending on the temperature measurement range.