JPS63234125A - Optical temperature measuring instrument - Google Patents

Abstract

PURPOSE:To measure temperature with high sensitivity by projecting and photodetecting light from a light source on an interference film filter as a temperature sensing part through an optical fiber, diffracting light from the optical fiber spectrally and detecting it by a detector, and measuring the temperature from their outputs. CONSTITUTION:The light from the light source 1 such as an incandescent lamp is projected on the multilayered interference film filter 3 as the temperature sensing part by the optical fiber 21 and light transmitted through the filter 3 is guided out through an optical fiber 22. The light from the fiber 22 is diffracted spectrally by a spectral diffracting means 4 such as a prism and detected by a detector 5, and a measuring means 6 measures the temperature from the output of the detector 5. Namely, the filter 3 shifts in transmission wavelength characteristics to the long- wavelength side from A to A' as the temperature T rises. Specific wavelength B of the light which is diffracted spectrally by the spectral diffracting means 4 and detected by the detector 5, on the other hand, is constant, 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 5 varies. Then the measuring means 6 measures the temperature T from the output of the detector 5 by an arithmetic expression found by an experiment, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an optical temperature measuring device using an optical fiber.

[Prior Art] Conventionally, there has been a device that uses a semiconductor or the like whose transmittance changes depending on temperature as a temperature sensing part, emits and receives light through an optical fiber, and measures the temperature from changes in the light receiving layer of the detector. be.

[Problems to be solved by this invention] However,
When a semiconductor or the like is used as the temperature-sensing section, the transmittance, etc., is determined by the properties of the material, and there are problems in that it is difficult to freely select the measuring section range and sensitivity as required.

In view of the above points, the purpose of this invention is l! ! An object of the present invention is to provide a 5A optical measuring device that uses an interference film filter as a filter and enables high-sensitivity measurement.

[Means for Solving the Problems] The present invention projects and receives light from the light source h11 through an optical fiber to an interference film filter, which is a temperature-sensitive part whose transmittance or reflectance changes depending on temperature, and generates an optical fiber. This is an optical temperature measurement device in which the light from a single fiber is separated by a spectroscopic means and detected by a detector, and the temperature is measured by a measuring means from the output of this detector.

[Example] FIG. 1 is an explanatory diagram showing the configuration of this embodiment.

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 such as a temperature sensing section, and the light is transmitted through an interference film filter 3 such as a bandpass filter. The light transmitted through the filter 3 is extracted by an optical fiber 22. The light from the fiber 22 is separated by a spectroscopic means 4 such as a diffraction grating or a prism, and the C
The light is received by an image sensor such as an OD or other detector 5,
The temperature is measured by the measuring means 6 from the output of the detector 5.

In other words, when the temperature T rises, the interference film filter 3
As shown in Figure 8, the transmission wavelength characteristic shifts to the long wavelength side, and the specific wavelength B that is separated by the spectroscopic means 4 and detected by the detector 5 is constant, so the degree of overlap between A or A' and 8 is (fi) 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 an arithmetic expression, table, etc., determined in advance through experiments, measurements, etc.

For the interference film filter 3, a multilayer film is formed by vapor deposition using Si or Ge for the high refractive index film and SiO for the low refractive S$ film, and the desired transmission wavelength is adjusted according to the temperature measurement range and sensitivity. The filter should have the following characteristics.

In this way, by changing the number of layers and the structure 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.
．． It is sufficiently large at 5X10-' and -'°C and can be used as a temperature-sensitive section.

FIG. 3 is a configuration explanatory diagram showing another embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same configuration i! ! Indicates the element.

In the figure, light from light source 1 passes through half mirror 7 at fF
L by optical fiber 2! ! The light is projected onto an interference filter 3 as a % warm section. The light reflected by an interference film filter 3 such as a bandpass filter provided at the tip of the optical fiber 2 by vapor deposition or other means is extracted again through the optical fiber 2 and reflected by the half mirror 7. The light reflected by the half mirror 7 is separated by a spectrometer VA4 and received by a detector 5 such as an image sensor, and the temperature is measured by a measuring means 6 from the output of the detector 5.

In other words, when the temperature T of the interference film filter 3 rises, the reflection wavelength characteristic shifts to the longer wavelength side, such as from A to A- in FIG. 4, and the wavelength detected by the detector 5 shifts from As shown in C, if one (B) changes the degree of overlap with the concave part of the interference film filter 3, and the other (C) does not change, the detector 5 for both wavelengths B and C changes. By calculating the ratio of the outputs by the measuring means 6, measurement errors caused by changes in the state of the optical path, etc. can be removed, making it possible to perform highly accurate measurements.

In addition, as shown in FIG. 5, in FIGS. 1 and 3,
When the light from the interference film filter 3 and the optical fiber 2.22 is separated and detected by the spectroscopic means 4, at least one or more detectors 5
1.52, and the measurement means 6 may perform ratio worship or other predetermined processing to perform the measurement.

In addition, as shown in FIG. 6, by forming the interference film filter 3 on the end face of the optical fiber 20 using a vapor deposition chopstick (for example, by forming the interference film filter 3 on the end face of many optical fibers at the same time), uniform The temperature sensing part can be produced inexpensively and easily, has compatibility, and can be attached to and detached from the optical fiber 2 using the optical connector 20a, making it easy to handle and handle.
Maintenance, etc. becomes easier.

[Effects of the Invention] As described above, this R-light uses an interference film filter as the temperature sensing part and extracts a specific wavelength using spectroscopy means, so it can be used to connect optical fibers with a simple configuration. Utilizing this, it is possible to measure temperature with stable R accuracy. Further, 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 the temperature with each scale according to the temperature measurement range, sensitivity, etc. Furthermore, if an image hinter is used as a detector, it becomes easy to set and change the measurement wavelength.

[Brief explanation of drawings]

1, 3, 5, and 6 are configuration explanatory diagrams showing a practical example of the present invention, and FIGS. 2 and 4 are wavelength characteristic diagrams.

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. an optical fiber for taking out the light, a spectroscopic means for separating the light from the optical fiber, a detector for receiving the light separated by the spectroscopic means, and a measuring means for measuring the temperature from the output of the detector. An optical temperature measuring device characterized by: 2. The optical temperature measuring device according to claim 1, wherein the measuring means measures the temperature from a ratio of outputs of a detector for two wavelengths. 3. The optical temperature sensor according to claim 1 or 2, wherein an image sensor is used as the detector, in which light of each wavelength separated from a spectroscopic means is incident on each element. measuring device. 4. Claims 1 to 3, characterized in that the detector is at least one detector that receives the separated light of each wavelength from the spectroscopic means through a slit. Optical temperature measuring device as described in .