Influence of Aberrations and Numerical Aperture of an Illumination Microscope Objective on the Quality of Pinhole Diffraction Wavefront

摘要

Point diffraction interferometer (PDI) uses the nearly ideal spherical wave front diffracted by the pinhole as the reference, thus its measurement accuracy depends mainly on the quality of the diffraction wave front. However, aberrations and numerical aperture (NA) of the microscope objective (micro-objective) used to illuminate the pinhole in PDI can affect the quality of the diffraction wave front and further reduce the measurement accuracy of PDI. It's necessary to analyze the influence of the micro-objective on the quality of the diffraction wave front detailly. In this paper, numerical simulation of the propagation of the incident light through the pinhole is carried out with the method of the finite difference time domain (FDTD), vector diffraction integral and vector diffraction theory. Then energy transmittance, homogeneity and deformation are obtained, which are used to evaluate the influence of the micro-objective on the quality of the diffraction wave front. These simulation results will provide a reference for rational selection of the micro-objective parameters, contributing to establish PDI system with best measurement accuracy.