Full-Range Line-Field Optical Coherence Tomography for High-Accuracy Measurements of Optical Lens

Abstract

A full-range line-field Fourier-domain optical coherence tomography (LF-FDOCT) system with an accuracy at nanoscale was proposed for high-accuracy measurements of optical lens surface profile. The LF surface curve information of optical lens could be obtained in one measurement which does not need point-by-point scanning used in the traditional 1-D FDOCT system. The measurement accuracy of surface profile curve could be improved from micrometer scale to nanoscale by applying spectral center correction method (SCCM) to the complex spectral interferogram. The corrected five phase-shifting (CFPS) method was employed to eliminate the complex-conjugate artifacts and the polychromatic error. The numerical simulation and experiment results demonstrated that the CFPS method had a better complex-conjugate suppression performance than other phase-shifting methods. Optical lens (e.g., cylindrical lens and spherical lens) was measured by the homemade LF-FDOCT system. After the analysis of the surface profile, the radius and the optical focal length of the measured lens were precisely obtained in a noncontact and nondestructive way. Therefore, the developed LF-FDOCT system has provided a new tool for high-accuracy measurements of optical lens surface profile and its parameters.