Strain sensor and strain detection method based on ring cavity ring-down spectroscopy

Abstract

The present invention provides an annular cavity ring-down spectroscopy-based strain sensor and a strain measurement method. According to the annular cavity ring-down spectroscopy-based strain sensor and the strain measurement method, continuous light emitted by an ASE light source passes through an optical polarizer and a photoelectric modulator so as to be converted into pulse light; the pulse light is decayed circularly several times in an annular ring-down cavity; in each circulation, only a small part of the signal light is outputted through the first output end of a second coupler, and then is detected by a photoelectric detector, and the remaining part of the signal light continues to be decayed in the annular cavity; when a sensing fiber grating is strained, the relative positions of the spectrum of the sensing fiber grating and the spectrum of an auxiliary fiber grating change, which results in the change of the loss of the annular ring-down cavity, and as a result, the ring-down time of the pulse signals changes, and therefore, the strain of the sensing fiber grating can be obtained through detecting the ring-down time of the pulse signals; and since the temperature responses of the sensing fiber grating and the auxiliary fiber grating are identical, temperature change will not change the loss of the annular ring-down cavity and the ring-down time of the optical pulse signals, and therefore, the sensor can realize automatic temperature compensation.

Description

technical field [0001] The invention relates to strain sensing technology, in particular to a strain sensor based on ring cavity ring-down spectrum technology. Background technique [0002] Fiber Bragg grating strain sensor uses laser as the carrier of strain information, and uses optical fiber to transmit laser light. Therefore, compared with the traditional electrical signal-based strain sensor, it has the advantages of electrical insulation, anti-electromagnetic interference, small size, light weight, and multiplexing. Therefore, it is widely used in civil engineering structures, aerospace industry, shipping industry, electric power industry, petrochemical industry, medicine, nuclear industry and other industries, especially in It has strong application advantages in harsh environments with high voltage, strong electromagnetic field, and flammable and explosive. [0003] Fiber Bragg grating is not only sensitive to strain, but also extremely sensitive to temperature. The...

AI Technical Summary

Problems solved by technology

[0005] Article 1 (Daqing Tang, Dexing Yang, Yajun Jiang, Jianlin Zhao, HaiyanWang, Shiquan Jiang, “Fiber loop ring-down optical fiber grating gas pressure sensor,” Optics and Lasers in Engineering , 2010, 48:1262–1265.) disclosed a pressure sensor based on optical fiber ring cavity ring-down spectroscopy technology and a single fiber grating. Although this sensor can theoretically improve the measurement sensitivity of the fiber grating, it cannot compensate for the ambient temperature Therefore, it can only be applied under constant temperature conditions; Article 2 (N. Ni, C. C. Chan, X. Y. Dong, J. Sunand P Shum, “Cavity ring-down long-period fibregrating strain sensor,” Measurement Science and Technology , 2007,18:3135–3138.) disclosed a strain sensor based on optical fiber ring cavity ring-down spectroscopy, long-period gratings and fiber-optic gratings. Since the responses of long-period gratings and fiber-optic gratings to temperature are different, the strain Sensors also cannot compensate for temperature effects

Images