Quadrature demodulation device for interference type photo-sensor based on pi/2 phase modulation

Abstract

The invention discloses a quadrature demodulation device for an interference type photo-sensor based on pi / 2 phase modulation. In the device, light output by a laser is divided into a signal sensing light path and a reference light path through a 1*2 coupler; on the signal sensing light path, a sensing signal output is acquired by a phase sensitive device of a sensing head; on the reference light path, a reference signal output is acquired by a pi / 2 phase modulator; the sensing signal output and the reference signal output are combined through a 2*1 light combiner, pass through a photoelectric detector and a low-noise amplifier sequentially and then are sampled by a digital signal processor; and the acquired data is divided into two paths according to odd-even positions and then is subjected to digital quadrature demodulation to acquired a sensing signal required to be demodulated. The device has the advantages of simple phase demodulation structure, simple and effective processing arithmetic, capability of effectively eliminating non-linear influences of devices and the like.

Description

technical field [0001] The invention relates to a quadrature demodulation device of an interferometric optical sensor, in particular to a quadrature demodulator of an interferometric optical sensor based on π / 2 phase modulation. Background technique [0002] With the rapid development of modern science and technology, human society is transforming from highly industrialized to informatized. Sensors, as an important way for people to obtain information, have attracted more and more people's attention and become the vanguard of the development of modern science and technology. . Optical fiber sensors have the advantages of anti-electromagnetic interference, small size, light weight, and high spatial resolution. It is easy to design into various shapes, easy to realize optical fiber transmission and long-distance telemetry, and easy to form a sensor network to achieve multi-point multi-parameter measurement. [0003] Interferometric optical fiber sensor has a complex structure...

AI Technical Summary

Problems solved by technology

The advantage of the heterodyne demodulation method is to avoid the associated AM interference. The disadvantage is that it needs to use a precise phase shift circuit of the heterodyne modulation signal. Once the phase is fixed, it cannot be adjusted with the change of the heterodyne modulation signal, and there is an inherent electronic phase drift. and serious noise interference

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