Research On Key Technology Of High Dynamic And Large Optical Path Closed-Loop Measurement Of Interferometer

The high sensitivity of optical fiber interferometer makes it widely used in modern sensing field.Increasing the fiber length of the sensing arm is an effective way to improve the measurement sensitivity and the measurement range,but the increase of the fiber length will lead to the increase of the optical path difference caused by the measurement signal.At the same time,in the modern measurement environment,the signal component of the target is increasingly complex.In this case,the improvement of the closed-loop detection bandwidth and range of the interferometer is the key to ensure the accurate measurement.The closed-loop measurement technology with high bandwidth and large optical path is the key technology to further improve the sensitivity and measurement range of the interferometer.Aiming at this problem,this paper studies and builds a general closed-loop measurement system based on fiber-optic interferometer,and achieves the purpose of high-precision closed-loop detection by precise compensation of high bandwidth and large optical path phase drift of system inputThe main contents of this paper are as follows:(1)Based on the analysis of the problems and limitations of the existing measurement methods of optical fiber interferometer,the scheme design of high bandwidth and large optical path closed-loop measurement system of optical fiber interferometer is completed based on the method of closed-loop work point control(2)The research of low-noise photoelectric detection technology is carried out,the analysis and modeling of optical and electrical noise in the photoelectric conversion process are completed,and the noise of photoelectric detection is reduced by optimizing the circuit topology and parameters,and the low-noise photoelectric detection circuit is designed and completed.(3)The research of high bandwidth and high precision digital control technology is carried out.The discrete domain transfer function model is built,the open-loop factors affecting the bandwidth and accuracy of the digital controller are analyzed,the system identification method of the complex control system is studied,and the performance evaluation model guiding the design of the digital controller is formed.The simulation test of PID and ripple free minimum beat digital control method is completed,and the digital controller is optimized by using the phase leading link and Smith prediction calculation method.(4)The high dynamic large optical path driving technology is studied.The research of high dynamic and large optical path actuator based on delay line and piezoelectric ceramic actuator is completed to ensure large dynamic range optical path compensation.The topology optimization of the high gain driving circuit is completed,and the high gain and low noise level are considered.(5)The experimental platform is built to verify the key technical performance indicators,achieving the closed-loop detection capability of 50 wavelengths under the control bandwidth of 1kHz,with the minimum error of 56dB.The optical path compensation capability of the closed-loop measurement system with large optical path and high bandwidth is verified.