Key Technology Of Micro Vibration Displacement Measurement System Based On Laser Interference Principle

The traditional micro-vibration displacement measurement method has been difficult to meet the requirements of modern industry for non-contact,long-term and high stability measurement.The interferometer designed by laser interferometry can solve this problem very well.However,most of the current laser interferometer optical system is easy to produce DC drift phenomenon in data due to environmental impact,which reduces the stability of the system.Moreover,the portable instrument and equipment are insufficient,and the measurement speed is slow.Therefore,in this paper,based on the principle of laser interferometry,the traditional interferometry system is analyzed and studied,and the optical path structure,hardware circuit and software algorithm are improved.A compact optical path structure and adaptive de-offset micro-vibration displacement measurement system are designed.Firstly,by comparing the advantages and disadvantages of homodyne interference and heterodyne interference in laser interferometry,the overall design of system measurement scheme based on homodyne interference principle is selected.Secondly,on the premise of reference homodyne interferometric optical path system,the optical path of the system is redesigned by using optical path micro-polarization method to improve the ability of obtaining clear interference fringes.Optical adjustability and miniaturization and portability of the system are realized by improving the optical mechanical structure.Thirdly,in terms of hardware and software systems,the ability of adaptive de-bias is realized by designing the de-DC bias circuit and the biasing program of dichotomy,which greatly eliminates the interference of DC drift caused by background light intensity.By designing a programmable amplifier circuit,the amplified signal suitable for subsequent data processing is obtained.Finally,the program of ellipse fitting algorithm and unwrapping algorithm is designed to transform the interference signal from displacement data.Displacement data are displayed in real time through the upper computer CVI control interface.The hysteresis comparison circuit is also designed to convert the interference sinusoidal signal into square wave signal.Through STM32 sampling,the fast fringe counting is realized,which provides conditions for improving the speed of displacement measurement.Finally,by measuring the output micro-vibration signal of the piezoelectric pendulum mirror,the related stability of the system is tested,and the improvement of the system in the future is put forward.