Micro-displacement Measurement Based On Vortex Optical Field Interference

Vortex light is a special vector light field,because of its characteristics of spiral phase wave front and central phase singularity,the light intensity distribution of vortex light is in the shape of concentric rings with a dark core at the center;in addition,there is stripe bifurcation phenomenon in vortex light interference image,which makes the image contrast improved.With the continuous improvement of vortex light theory and the rapid development of vortex light in optical micro-operation,superior resolutive imagery,optical communication and other fields,researchers are increasingly applying the phase properties of vortex light in the field of high-precision measurement.In order to meet the demand for higher measurement accuracy of components in the manufacturing field,the introduction of vortex light into miniature measurement field helps advance optical non contact measuring technology,which is of great significance for the progress of the field.Based on the interferometric properties of vortex light,this paper proposes a new scheme to measure the displacement of an object using vortex light phase shift interferometry.The scheme consists of two main parts,which are the design of the measurement optical path and the image processing.The design of the measurement optical path is achieved by adding a vortex wavelet to the conventional electronic scattering optical path,using the vortex light as the reference light and a piezoelectric ceramic to control the generation of phase shift,and the spherical wave as the measurement light to measure the displacement of the object.The image processing is a study of three commonly used filtering methods,the least-squares unwrapping algorithm,and an improved algorithm for phase correction based on the intensity transfer equation,and a comparative analysis of the denoising effect of the three filtering algorithms,and a comparison of the effect of the improved least-squares unwrapping algorithm on phase recovery before and after.In the scheme,the vortex light is generated by the vortex wave sheet,and the CCD camera acquires the interference image containing the effective information,and the displacement of the object is obtained by combining the phase-shift interference principle and the phase unwrapping algorithm.Then,the feasibility of the measurement scheme is verified by simulating and analyzing the scheme with the optical software Virtual Lab Fusion.The experimental results are obtained by building the experimental system of the above measurement scheme,and the results show that the object displacement obtained by using the improved least squares algorithm is 0.33 μm smaller than the displacement error obtained by the commonly used least squares algorithm when the displacement is 15 μm.Finally,the superiority of the scheme in this paper is verified by comparing it with the scheme of calculating the rotation angle to find the object displacement.