A distributed optical fiber laser ultrasonic transducer based on coreless optical fiber

Abstract

The invention provides an optical fiber laser distributed ultrasonic transduction device based on non-core optical fibers. A pulse seed resource, a high-power Er-doped optical fiber optical amplifier,a high-power optical fiber isolator and an energy coupling structure with the non-core optical fibers are sequentially connected to form an ultrasonic transducer stimulation system. The ultrasonic transduction device of the energy coupling structure with the non-core optical fibers is composed of non-core optical fiber units of different lengths. The specific structure of each unit is a single mode fiber-non-core optical fiber-single mode optical fiber structure, and the laser energy coupling ratio of each non-core optical fiber unit is determined by the length of the corresponding non-core optical fibers. By means of the ultrasonic transducer stimulation system, the coupling ratios of the non-core optical fiber units are sequentially connected according to the sequence from small to large, a lead-out single-mode optical fiber cladding layer in the energy coupling structure of the non-core optical fibers is removed, a laser absorbing material is arranged in a filling manner, ultrasonic signals are generated through materials with the high heat absorption coefficient and the high thermal-elastic coefficient, and distributed ultrasonic signal balanced stimulation is achieved.

Description

Technical field [0001] The invention relates to the field of fiber laser ultrasonic excitation, in particular to a balanced fiber laser multi-point ultrasonic excitation transducer device based on a coreless fiber. Background technique [0002] In recent years, more and more attention has been paid to the structural health of important facilities such as civil buildings, industrial engineering, and aerospace structures. A series of environmental factors, such as high temperature, strong corrosion and severe collision, may have a destructive effect on the health of these structures. Therefore, for important structures, structural health detection and performance monitoring are particularly important. In particular, the timely detection and repair of initial damaged structures can avoid casualties and economic losses. Non-destructive testing technology is an ideal structural health monitoring method, which will not cause damage to the tested structure and can detect a wide range o...

AI Technical Summary

Problems solved by technology

Based on the idea of ​​multi-point ultrasonic excitation on the fiber side wall, multi-point ultrasonic excitation is realized by controlling the longitudinal misalignment of the optical fiber, which solves the problem that the inclined fiber Bragg grating ultrasonic transducers cannot be excited at the same time, but this longitudinal The amount of misalignment drastically reduces the radial and axial mechanical properties of the optical fiber, the optical fiber becomes very fragile, and is easily broken under the action of external force, and the control accuracy of the fusion splicer used in this method is not high, and system errors are likely to occur, making the preparation The energy radiation ratio of the ultrasonic transducer does not meet the requirements

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