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Point contact fiber optic ultrasonic sensor

An ultrasonic and sensor technology, applied in the field of measurement, can solve the problems of staying at the highest response frequency, unsatisfactory high-frequency ultrasonic response characteristics, reduced sensor sensitivity, etc., to achieve the effect of real-time monitoring

Inactive Publication Date: 2016-04-27
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the limitation of the slender structure of the optical fiber, the fiber-optic ultrasonic sensor researched and developed at present, the response characteristics to high-frequency ultrasonic waves are not ideal.
At present, the highest response frequency of most ultrasonic sensors only stays between tens of kHz and hundreds of kHz, and it is difficult to cover the spectrum range of high-frequency ultrasonic waves generated by partial discharge.
On the other hand, at present, most types of fiber optic ultrasonic sensors are still of the surface contact type, so there are still certain requirements for the flatness of the contacted solid surface.
Often due to the unsatisfactory surface coupling state and frequent changes, the sensitivity of the sensor is greatly reduced, and many uncertain factors are brought to the measurement process

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0046] Referring to Fig. 1 and Fig. 2, this point-contact optical fiber ultrasonic sensor includes a core part and a package shell, and is characterized in that: the core part is made of an optical fiber ultrasonic sensitive element; the package shell is an electrical insulation shell; the fiber optic ultrasonic sensor Sensitive elements are encapsulated in the electrical insulation shell to form a single sensor.

Embodiment 2

[0048] This embodiment is basically the same as Embodiment 1, and the special features are:

[0049] The optical fiber ultrasonic sensitive element consists of a single-mode optical fiber coated with a polyimide resin film on the surface, an optical fiber F-P resonant cavity formed by two spaced fiber gratings, and a ceramic plug glued together with the head of the single-mode optical fiber. Core composition.

[0050] The packaging structure in which the sensitive element of the optical fiber sensor is encapsulated in the electrical insulation shell applies effective stress to the optical fiber F-P resonant cavity in advance, so that the sensor has the function of sensing high-frequency ultrasonic waves.

[0051] The inner end surface of the ceramic ferrule is supported by a plastic spring, and the plastic spring is installed in the inner hole of the packaging shell in a compressed state, and applies effective stress to the optical fiber F-P resonant cavity in advance.

Embodiment 3

[0053] The fiber optic ultrasonic measurement system related to the embodiment of the present invention as shown in Fig. 2(a) is used as an example below to illustrate the measurement of the ultrasonic signal propagating in the surface layer of the metal flat plate by using the point contact optical fiber ultrasonic sensor of the present invention.

[0054] For example, a point-contact fiber optic ultrasonic sensor 10 can be formed by using the fiber optic ultrasonic sensor shown in FIG. 1( a ) and the package structure of the sensor shown in FIG. 1( b ).

[0055] For example, using the fiber optic ultrasonic sensor shown in Figure 1(a), the center wavelength of the two fiber gratings 2a and 2b is 1552.3nm, the line width is 1.8nm, the reflectivity is 10%, and the fiber F-P resonant cavity length L The surface is coated with a single-layer polyimide resin film, and the ceramic ferrule is the fiber optic connector material, with an outer diameter of 2.5mm and a length of 10.5mm....

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Abstract

The invention discloses a point contact type ultrasonic wave sensor based on the fiber grating technology. The sensor comprises a core portion and a packaging shell. The core portion is composed of a fiber ultrasonic wave sensitive element; the packaging shell is an electric insulating shell; the fiber ultrasonic wave sensitive element is packaged in the electric insulating shell, and the one-body sensor is constituted. The point contact type ultrasonic wave sensor is small in size, does not have any metal part, has the low requirement for the flatness of the surface of a measured point, is capable of achieving point contact measurement, is particularly suitable for detecting high-frequency ultrasonic wave signals produced through partial discharging in high-voltage transmission transformers, gas insulated switchgears and other high-voltage equipment, and is novel.

Description

technical field [0001] The invention belongs to the field of measurement, and in particular relates to a point-contact optical fiber ultrasonic sensor for detecting high-frequency ultrasonic vibrations propagated on a solid surface. technical background [0002] In the industrial field, traditional piezoelectric ceramic ultrasonic sensors based on the piezoelectric effect have been used for a long time to measure ultrasonic signals transmitted in solid objects such as metals or on their surfaces. However, the piezoelectric ceramic ultrasonic sensor has high requirements on the flatness of the contact part of the solid surface, and it cannot be used directly for some irregular surfaces, such as curved surfaces. On the other hand, in order to obtain high detection sensitivity, it is necessary to maintain good contact between the sensor surface and the solid surface. When in use, it is often necessary to apply an acoustic wave coupling medium between the two contact surfaces, ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01H9/00
Inventor 王陆唐方捻黄肇明
Owner SHANGHAI UNIV
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