JPS63234126A - Optical temperature measuring instrument - Google Patents

Abstract

PURPOSE:To measure temperature with high sensitivity by projecting and photodetecting laser light with specific wavelength on an interference film filter as a temperature sensing part through an optical fiber, detecting light from the optical fiber by a detector, and measuring the temperature. CONSTITUTION:Light from a laser light source 1 which generates the laser light with the specific wavelength is projected on the multilayered interference film filter 3 as the temperature sensing part through the optical fiber 21. Light transmitted through the filter 3 is guided out through an optical fiber 22 and photodetected by the detector 4, and a measuring means 5 measures the temperature from the output signal of the detector 4. Namely, the filter 3 shifts in transmission wavelength characteristics to the long-wavelength side from A to A' as the temperature T rises and the wavelength of the laser light is constant as shown by B, so the degree (product) of the overlap between A or A' and B varies with the temperature T and radiant energy incident on the detector 4 varies. The measuring means 5 measures the temperature T from the output of the detector 4 by an arithmetic expression found by an experiment, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to optical temperature measurement Qi using an optical fiber.
This is related to lflJ.

[Prior art] Conventionally, a semiconductor or the like whose transmittance changes depending on temperature is used as a wet 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 to be solved by this invention] However,
! ! When a semiconductor or the like is used as the I m 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] This invention projects and receives laser light of a specific wavelength through an optical fiber to an interference film filter as a temperature-sensitive part whose transmittance or reflectance changes depending on temperature. This is an optical temperature measuring device that detects laser light from a fiber with a detector and measures temperature with a measuring means.

[Example] FIG. 1 is a configuration explanatory diagram showing an example of tJ color according to the present invention.

In the figure, light from a laser light source 1 that generates a laser beam of a specific wavelength is projected through an optical fiber 21 to a multilayer interference film filter 3 as a temperature sensing section. The light transmitted through the router is taken out by an optical fiber 22. The light from the optical fiber 22 is received by the detector 4, and the temperature is measured by the measuring means 5 based on the output signal of the detector 4.

In other words, the transmission wavelength characteristic of the interference film filter 3 shifts to the longer wavelength side as shown in Fig. 2 △13 days to △- when WKIT becomes full, and the wavelength of the laser light from the laser light source 1 changes to Fig. 2 B. Since it is constant as shown by , the overlapping degree (product) of A or 8 and 8 changes depending on the temperature T, and the radiant energy incident on the detector 4 changes. The output of this detector 4 is measured by the measuring f stage 5.
Measure the temperature T from the test results obtained using a gauge, table, etc.

As the interference film filter 3, a multilayer film is formed by vapor deposition using Si or Qe for the high refractive single film and Si○ for the low refractive index film, and the desired transmission wavelength is adjusted according to the temperature measurement range and sensitivity. A filter with characteristics.

In this way, by changing the number of layers and film configuration of the multilayer interference film filter, a filter with the required bandpass characteristics can be obtained, and the temperature coefficient of the refractive index of 3i and Qe is approximately 1.5X10-', /'C and big enough! It can be fully used as an ia lagoon.

FIG. 3 is a configuration explanatory diagram showing another embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate equivalent components.

In the figure, 1 is a laser diode or other laser light source consisting of a laser that can switch between lasers that generate laser beams of different wavelengths or that can generate laser beams of different wavelengths; The laser beam with a longer wavelength from 1 is sent to the half mirror 6.
The light is projected onto an interference film filter 3 via an optical fiber 2.

Light reflected from an optical fiber 3 such as a bandpass filter provided at the tip of the optical fiber 2 is extracted again via the optical fiber 2 and reflected by the half mirror 6. The light reflected by this half mirror 6 is received by the detector 4,
The temperature is measured from the output of the detector 4 by the measuring means 5.

In other words, the interference membrane filter 3
The reflection wavelength characteristic shifts to the long wavelength side from Δ to 3. The degree of depression in the depressed part changes, and the other (C
) does not change, by calculating the ratio of the output of the detector 4 for both wavelengths B and C using the measuring means 5, it is possible to eliminate J stiffness measurement errors due to changes in the state of the optical path, etc., and achieve high accuracy. measurement becomes possible.

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 section can be produced in large quantities at low cost, has compatibility, and is easy to handle, maintain, etc. since it can be attached to and detached from the optical fiber 2 using the optical connector 20a.

[Effects of the Invention] As described above, the present invention uses an interference film filter as the temperature sensing section and a laser light source to emit stable light of a specific wavelength. This allows for low humidity. In addition, the interference film filter can freely change the transmission wavelength characteristics etc. by changing the film configuration etc., and it becomes possible to easily measure various temperatures depending on the temperature measurement range, sensitivity rσ, etc.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 3, and FIG. 5 are configuration explanatory diagrams showing one embodiment of the present invention, and FIG. 2 and FIG. 4 are explanatory diagrams of wavelength retention. DESCRIPTION OF SYMBOLS 1... Laser light source, 2.20.21.22... Optical fiber, 3... Interference film filter, 4... Detector, 5... Measuring means, 6... Half mirror 120a.
...Optical connector figure 3 '201L rod? Kasumi Figure 4

Claims (1)

[Claims] 1. An interference film filter as a temperature sensitive part whose transmittance or reflectance changes depending on temperature, and a laser beam of a specific wavelength from a laser light source projected onto the interference film filter. an optical fiber that extracts transmitted or reflected laser light; a detector that receives light from this optical fiber;
An optical measuring device comprising a measuring means for measuring temperature from the output of the detector. 2. The optical temperature measuring device according to claim 1, wherein the laser light source emits light of different wavelengths.