SU951087A1 - Device for measuring temperature - Google Patents

Description

in the form of a light guide with a frosted shell and a photodetector, while the dark floor condenser is optically coupled to a temperature-sensitive element and a light source, the input of which is electrically connected to the output of the alternator, and the output of the photodetector connected to the inputs of the resonant amplifier and recorder.

FIG. 1 is a schematic of an embodiment of the device according to FIG. 2; a section A-A in FIG. 1 (thermosensitive element, made in the form of a light guide).

A device for measuring temperature (Fig. 1) contains a light source 1, for which an LED is used, an alternator 2 connected to a light source 1, a condenser; dark field 3, spectral 4 and spatial 5 filters, photodetector 6 (photodiode) resonant amplifier 7 connected to a photodetector, a recording device 8 connected to the output of the resonant amplifier and a temperature-sensitive element 9.

FIG. 1 shows a temperature-sensitive element 9, made in the form of a light guide, comprising a shell 10 of a light guide 9 and a core 11 of a light guide.

The condenser of the dark floor 3 is installed in front of the light source 1. Spectral -4 and spatial 5 filters are installed in series in front of the photodetector. B. The thermosensitive element 9 is made in the form of a light guide consisting of a shell 10, the outer surface of which is matted, and the core 11 with temperature refractive indices of different sign or size. As an embodiment, the fiber can be made of three sections connected in series, the outermost of which have a large numerical aperture and a small dependence of the refractive indices of the core and the cladding on temperature, and for the middle section the shell 10 is made of a silicon compound of the type CEEL having 20 ° C - 1.4, and at BO ° C - 1.47. The core material is an LK-b optical glass with a refractive index of 1.47. The spectral characteristics of the light source 1,. spectral filter 4 and photodetector b are consistent. The resonant frequency of amplifier 7 is equal to the operating frequency of the alternator 2.

 The spatial filter 5 is an opaque disc made on the glass plate by the photo-method, and is intended to prevent the photodetector from falling into

light beams emerging at small angles to the fiber axis.

The device works as follows.

Light radiation from light source 1, modulated by intensity by alternating current generator 2, by means of a dark field condenser 3 is introduced through the end surface into the optical fiber temperature-sensitive element 9. In this case, the dark field condenser 3 serves to separate the light flux supplied to the input section of the fiber , into the system of rays most sensitive to the imme ement of the refractive index of the fiber envelope. By unloading the photodetector from uninformative rays that are close to normal to the end surface of the fiber, the dark field condenser at the same time gives rise to the level of light fluxes and, consequently, the signals from the photodetector output.

In the fiber, the highest wave types are excited, the highest order of which

5 is determined by the difference in the refractive indices of the cladding 10 and the core 11. From the output end of the fiber, the spectral 4 and spatial 5 radiation comes from the filters and hits the photodetector b. The electrical signal from the output of the photodetector is amplified by a resonant amplifier 7 and is fed to a recording device 8. The spatial filter 5 separates from the entire cone of rays with

5 of the output end of the fiber, only the rays at angles corresponding to the highest light emission modes are most sensitive to the difference between the refractive indices of the core 11 and the shell 10. When the ambient temperature rises, the refractive index of the cladding decreases, while practically the core refractive index

5 does not change, and as the difference between the refractive indices of the core and the cladding increases, an increasing amount of energy passes to the photodetector 6. In case of equality of indicators

When the core and the shell are refracted, the luminous energy is completely dissipated on the matted surface of the shell and there is no signal at the output of the photodetector. The unequivocal dependence of the light transmission of the temperature-sensitive element 9 on temperature makes it possible to realize a device for measuring temperature in a wide range of temperatures.

In order to reduce the errors

Claims (2)

 measuring the temperature due to the low noise immunity of the device from extraneous light sources, a spectral filter 4 was introduced into the device; it attenuated the light from external sources with a spectral composition different from the filter bandwidth and the additional noise immunity of the device at the transmission wavelength spectral filter 4 provides a resonant amplifier 7, operating on the operating frequency of the alternator 2. The technical and economic effect of using The results are reduced in decreasing the temperature measurement error to 0.1% and in expanding the range of measured temperatures from to + 200 ° С, and for the modified SIEL material from -80 ° С to + 200 s, taking into account the noise immunity of the device from external light and electromagnetic fields in the measurement speed to a value of 0.10 due to the frosted surface of the fiber cladding and its small size. Thus, a temperature measuring device is widely used in a national household. Claim device A temperature measuring device containing a thermosensitive element optically coupled to a photoreceiver and a light source, a recorder, characterized in that, in order to improve the measurement accuracy and extend the range of measured temperatures, an alternating current generator and a resonant amplifier are introduced into the device , dark field condenser, spectral and spatial filters placed successively along the optical axis between the temperature-sensitive element made in the form of a light guide with a ma th e shell, and a photodetector, the dark field condenser is optically coupled with the temperature sensor and a light source having an input electrically connected to vosodom alternator and vosod photodetector connected to the inputs of the resonance amplifier and recorder. Sources of information taken into account in the examination 1. The author's certificate of the USSR 1 464792, cl. G 01 K 11/12, 1972. 2. USSR author's certificate number 495559, cl. G 01 K 11/12, 1974 (prototype).