Vortex Light Coaxial Interference Micro Displacement Detectio

In recent years,laser measurement technology has become a research hotspot in precision measurement fields such as precision industry,medicine and military manufacturing.At present,laser precision measurement mostly uses Gaussian beams to achieve measurement purposes by interferometry,grating diffraction method,etc.,and these methods generally have problems such as complex measurement equipment,high cost and poor stability.Vortex beam is a beam with spiral phase factor exp(ilφ),and its unique intensity,phase,interference diffraction characteristics are widely used in optical communications,particle manipulation and optical measurement.In this paper,it is proposed to use Optical Vortices(OV)carrying Orbital Angular Momentum(OAM)for micro-displacement monitoring,and the main work results are as follows:First,the interference characteristics of vortex beam and the relationship between displacement and interference field change are studied,and the simulation and verification of vortex optical coaxial interference micro ranging are realized.Combined with the classical Michelson interferometer,a microdisplacement measurement method based on OAM laser coaxial interference is proposed.It solves the problems of difficult rounding and low resolution of traditional laser interferometric ranging fringes,converts the displacement into the rotation angle of the central symmetric interference field,and designs the measurement system by constructing a mapping relationship between the displacement and the rotation angle,and obtains the simulated light field of microdisplacement measurement.Second,design and build a vortex optical interference micro displacement detection system to achieve nanometer displacement measurement.For the first time in data acquisition and signal processing,electrical signal data is used to accurately measure small displacement changes and velocity changes of objects.The periodic electrical signal data corresponding to the object displacement were fitted,and the average relative error of 20 groups of parallel experimental results with small displacement(250nm),medium range displacement(2μm)and large displacement(20μm)was less than 1.15%,and the precision measurement of small displacement was completed.It realizes the monitoring and analysis of the onedimensional motion state of the object,and can calculate the moment and position of the speed change of the object,and the motion speed before and after the change.The measurement system has the advantages of small error,fast speed,no contact,and low cost.Based on the macro measurement technology of vortex optical interference principle,this paper realizes large-range and high-precision measurement of microdisplacement,and completes the detection and analysis of the motion state of microspeed objects.These works have certain reference value for the development of precision measurement,control and object micromotion analysis.