RU81323U1 - COMBINED FIBER OPTICAL PRESSURE AND TEMPERATURE SENSOR - Google Patents

Abstract

The device relates to measuring equipment and can be used for remote monitoring of pressure and temperature in the oil industry, the electrical industry, geological exploration, etc. The technical problem is the improvement of the measuring device. The technical result is to increase the accuracy of pressure measurements by taking into account the additional error of temperature. It is achieved by the fact that the known device additionally introduces beam splitters, micro lenses, a micro positioner, a collimating lens, a working single-mode fiber with an aluminum coating for measuring temperature, an articulator, a collecting lens, a photodetector, a signal power amplifier, a processing unit, and a thermal compensation circuit.

Description

The utility model relates to the field of measurement technology and can be used for remote monitoring of liquid pressure and temperature in the oil industry, the electrical industry, geological exploration, etc.

Known fiber optic sensor [see RF patent No. 2205374, 2003]. This sensor allows you to measure fluid pressure. Its disadvantage is low sensitivity.

Closest to the alleged invention is a fiber optic interferometer designed to measure pressure in a liquid [see Busurin VI, Nosov Yu.R.] Fiber-optic sensors: physical fundamentals, calculation and application issues. - M .: Energoatamizdat, 1990. 256 pp.], Containing a semiconductor or gas laser, a device for inputting radiation into an optical fiber, an optical fiber, laser radiation is collimated by the system and fed through an optical fiber to a translucent plate or beam splitter, micro-lenses, micro-positioners . Most of the working fiber is placed in the test volume, and the reference fiber is in stable external conditions. At the output of the working and supporting fibers, collimating lenses are introduced, which convert diverging fronts into flat ones. To combine these fronts so that it is possible to observe the pattern of interference of the working and reference waves, an articulator is used. The photodetector, which is located in the focus of the collecting lens, registers the result of interference of the reference and studied waves. Power

the signal detected at the photodetector, and therefore, at the output of the amplifier and at the input of the recording circuit, depends on the amplitude of the phase modulation.

The known sensor is intended for use at a constant temperature and is characterized by a high additional error during temperature fluctuations of the measured object. To account for the effect of temperature, an additional temperature sensor must be used.

The technical task is to improve the measuring device and expand the functionality by increasing the number of sensitive elements.

The technical result is to increase the accuracy of measurements and eliminate errors when measuring pressure and temperature.

The technical result is achieved by the fact that the known device has an additional two beam splitters with 50% transparency, two micro-lenses, a micro positioner, a collimating lens, a working single-mode fiber with an aluminum coating for measuring temperature, an articulator collecting lens located in series along the beam of radiation, the radiation output from the optical fiber is a photodetector, amplifier, processing unit and thermal compensation circuit.

The proposed combined pressure and temperature sensor is illustrated by the drawing shown in figure 1 (General view and section along the lines aa and bb).

The combined optical fiber pressure and temperature sensor comprises a laser emitter 1, a device for introducing radiation into the optical fiber 2, an optical fiber 3, a collimating system 4 made of two sequentially arranged components: a meniscus and a biconvex lens, a reference fiber 12, a working fiber 13, a working one aluminum coated fiber 14 in the intermediate portion of the optical fiber

beamsplitters 5, 6, 7, micro-lenses 8, 9, micropositioners 10, 11, articulators 18, 19, collecting lenses 20, 21, photodetectors 22, 23, amplifiers 24, 25, processing units 26, are located at the exit from the optical fibers 27, thermal compensation circuit 28.

The device operates as follows.

The radiation of the laser 1 by the radiation introducing device 2 is introduced into the optical fiber 3 and collimated by the system 4. The beam splitter 5 divides the light flux into two fluxes, one of which is designed to measure temperature. The second stream of the beam splitter 6 is again divided into two streams: investigated for determining pressure and reference. The reference and studied flows are used to create an interference pattern. After the beam splitters 5 and 6, the micro-lenses 8 and 9 focus the optical fluxes onto the input ends of the workers 13, 14 and the reference 15 of single-mode fibers. To ensure efficient input of radiation into the fibers, micropositioners 10 and 11 are used (three-coordinate motions with an installation accuracy of 1 μm). Most of the working fibers 13 and 14 are placed in the test volume, and the reference fiber 12 is in stable external conditions. The phase change in the working fiber 13 occurs when exposed to pressure. The phase change in the working fiber 14 occurs when exposed to temperature. The heating of the working fiber 14 having an aluminum coating affects the phase change of the radiation propagating in the fiber as a result of a change in the length of the fiber and a change in its refractive index. At the exit from the optical fibers 12, 13, 14, collimating lenses 16, 17 are introduced, which convert the diverging radiation fronts into flat ones.

Articulators 18 and 19 are used to combine wave fronts so that in the planes 29 and 30 it was possible to observe the pattern of interference of the working and reference waves. It is known that if in a certain region of space there are two coherent and in the same way

polarized waves whose wave vectors (respectively and ) differ only in direction, the angle between and equal to Θ _1.2 , then in the plane perpendicular to the bisector of the angle Θ _1.2 , a pattern of interference fringes with a period Λ will be observed.

The interference bands are directed perpendicular to the plane 30 (31), in which the wave vectors lie and , as shown in section AA in figure 1. By adjusting the inclination of the articulators 18, 19 (the angle Θ _1.2 varies), it is necessary to adjust the interference pattern in such a way as to achieve the optimal period of interference fringes Λ. The interference pattern detected by the photodetectors 22, 23 depends on the phase modulation amplitude, an amplifier 24 and a processing unit 26 are arranged in series at the output of the photodetector 22, an amplifier 25 and processing unit 27 are arranged in series at the output of the photodetector 23. To exclude additional error of pressure measurement from temperature, thermal compensation circuit 28.

The use of an optical fiber with an aluminum coating in the proposed combined optical fiber pressure and temperature sensor as a sensing element distinguishes the proposed sensor from known devices because it expands the functionality and eliminates errors when measuring pressure and temperature.

Sources

1. RF patent No. 2205374, 2003

2. Busurin V.I., Nosov Yu.R. Fiber optic sensors: physical fundamentals, calculation and application issues. - M .: Energoatamizdat, 1990.256 s.

Claims (1)

Combined fiber-optic pressure and temperature sensor containing a laser emitter, a device for inputting radiation into an optical fiber, an optical fiber, a collimating system, a beam splitter, micro lenses, micro positioners, a reference and working single-mode fibers for measuring pressure, collimating lenses, a collecting lens, a photodetector, an amplifier , a processing unit, characterized in that two additional beam splitters, two micro-lenses, a micropositioner, a collimating lens, arranged in series, are introduced into it along the radiation beam, a working single-mode fiber with an aluminum coating for measuring temperature, an articulator, a collecting lens, the focus of which is a photodetector, at the output of which there is a signal power amplifier, processing unit, thermal compensation circuit.