RU2014123475A

RU2014123475A - FIBER OPTICAL PRESSURE SENSOR

Info

Publication number: RU2014123475A
Application number: RU2014123475/28A
Authority: RU
Inventors: Владимир Александрович Григорьев; Анатолий Григорьевич Летяго; Анатолий Николаевич Мартьянов; Александр Алексеевич Рахманов; Олег Владимирович Шавкунов
Original assignee: Владимир Александрович Григорьев; Анатолий Григорьевич Летяго; Анатолий Николаевич Мартьянов; Александр Алексеевич Рахманов; Олег Владимирович Шавкунов
Priority date: 2014-06-10
Filing date: 2014-06-10
Publication date: 2015-12-20

Abstract

1. Волоконно-оптический датчик давления, состоящий из оптоэлектронного блока с источником и приемником излучения, мембранного чувствительного элемента и волоконно-оптического преобразователя, оптический торец которого закреплен в корпусе чувствительного элемента и обращен к мембране, а торцы передающего и приемного световодов оптически связаны соответственно с источником и приемником излучения, отличающийся тем, что для уменьшения оптических потерь в зоне измерения волоконно-оптический преобразователь выполнен на основе конвертора диаметра поля моды, который внутри корпуса чувствительного элемента в пространстве «излучающий торец - мембрана» только одним излучающим торцом конвертера формирует состоящую из двух оптических элементов оптическую систему направления и распределения потока излучения, содержащую излучающий торец световода конвертора и образованный им на мембране отражательный торц, причем излучающий торец направляет излучение на мембрану, а отражательный торец распределяет отраженное от мембраны излучение по излучающему торцу, при этом излучающий торец имеет постоянные оптические и геометрические параметры, а отражательный торец - переменные оптические и геометрические параметры, величина которых зависит от расстояния и параметров среды между торцами, при этом функция преобразования датчика определяется зависимостью:где 2r=2+z·tgq, sinq=NA, q - апертурный угол световода;- радиус сердцевины излучающего световода;r - радиус сердцевины отражающего световода;z - расстояние между торцами световодов;x - поперечное смещение осей волоконных световодов;n - показатель преломления окружающей среды1. Fiber-optic pressure sensor, consisting of an optoelectronic unit with a radiation source and receiver, a membrane sensitive element and a fiber-optic transducer, the optical end of which is fixed in the housing of the sensitive element and facing the membrane, and the ends of the transmitting and receiving optical fibers are optically connected respectively with radiation source and receiver, characterized in that to reduce optical loss in the measurement zone, the fiber-optic converter is based on the converter the diameter of the mode field, which inside the case of the sensing element in the “emitting end-membrane” space, with only one emitting end of the converter forms an optical system of direction and distribution of the radiation flux consisting of two optical elements, containing the emitting end of the converter’s optical fiber and the reflective end formed by it on the membrane, the emitting end sends radiation to the membrane, and the reflective end distributes the radiation reflected from the membrane along the emitting end, while the end face has constant optical and geometric parameters, and the reflective end has variable optical and geometric parameters, the value of which depends on the distance and medium parameters between the ends, and the sensor conversion function is determined by the dependence: where 2r = 2 + z · tgq, sinq = NA , q is the aperture angle of the optical fiber; is the radius of the core of the emitting optical fiber; r is the radius of the core of the reflecting optical fiber; z is the distance between the ends of the optical fibers; x is the lateral displacement of the axes of the optical fibers; n is the refractive index of the environment

Claims

1. Fiber-optic pressure sensor, consisting of an optoelectronic unit with a radiation source and receiver, a membrane sensitive element and a fiber-optic transducer, the optical end of which is fixed in the housing of the sensitive element and facing the membrane, and the ends of the transmitting and receiving optical fibers are optically connected respectively with radiation source and receiver, characterized in that to reduce optical loss in the measurement zone, the fiber-optic converter is based on the converter the diameter of the mode field, which inside the case of the sensing element in the “emitting end-membrane” space, with only one emitting end of the converter forms an optical system of direction and distribution of the radiation flux consisting of two optical elements, containing the emitting end of the converter’s optical fiber and the reflective end formed by it on the membrane, the emitting end sends radiation to the membrane, and the reflective end distributes the radiation reflected from the membrane along the emitting end, while the end face has constant optical and geometric parameters, and the reflective end face has variable optical and geometric parameters, the value of which depends on the distance and medium parameters between the ends, while the sensor conversion function is determined by the dependence:

where 2r = 2 a + z · tgq, sinq = NA, q is the aperture angle of the fiber;

a is the radius of the core of the emitting fiber;

r is the radius of the core of the reflecting fiber;

z is the distance between the ends of the optical fibers;

x is the lateral displacement of the axes of the optical fibers;

n is the refractive index of the environment;

n ₁ is the refractive index of the core of the reflecting fiber;

NA is the numerical aperture of the optical fibers;

L is the reflection coefficient of the membrane.

2. The sensor according to claim 1, characterized in that the space inside the housing of the sensing element is represented by an optical system (a set of optical elements) created for a specific formation of beams of light rays.

3. The sensor according to claim 1, characterized in that the equivalence of the end-membrane system and the end-end system is accepted.

4. The sensor according to claim 1, characterized in that the theory of optical waveguides is applied to the end-to-end system, which is extended to the field of measuring transducers, and the sensor conversion function is obtained on the basis of this theory.

5. The sensor according to claim 1, characterized in that the membrane is matched with the receiver and the radiation source along the emitter wavelength.

6. The sensor according to claim 1, characterized in that the transceiver channel is matched according to the aperture angle.

7. The sensor according to claim 1, characterized in that the measuring path has an almost unlimited bandwidth.

8. The sensor according to claim 1, characterized in that the electrical circuit of the optoelectronic unit is made with alternating current.

9. The sensor according to claim 1, characterized in that it measures any industrial frequency of oscillations of the membrane or other physical object.

10. The sensor according to claim 1, characterized by a small value of the temperature error.

11. The sensor according to claim 1, characterized by a stable zero setting.