Improvement on measuring precision of a optical fiber sensor

based on principle of laser interference

was proposed through the investigation of both the optical system and the opticalelectron measuring system. The theoretical foundation

the selecting principle of circuit parameters and the designing method of preamplifier were given and analyzed in detail for the phase modulation of low noise of weak signal and the demodulation procedure of telephone digits. A precision of 0.05nm for micro-displacement measurement has been obtained by this new method.