Full-field optical coherence tomography by achromatic phase shifting with a rotatinghalf-wave plate

Abstract

An achromatic phase shifter with a rotating half-wave plate (HWP) and a full-field opticalcoherence tomography (FF-OCT) system based on it are presented. The novelconfiguration of this phase shifter in the FF-OCT system can achromaticallyprovide a phase shift of eight times the rotation angle of the HWP. The theoreticalcalculation of the phase shift and numerical analysis of the phase shift error,as well as the amplitude ratio, are conducted by means of Jones matrices. Theactual phase shift has also been measured to confirm the validity of the ‘8θ phase shift—HWProtation angle θ’ relation. The coherent image of a mirror has been obtained by using the Hariharanalgorithm to verify the phase shifter’s feasibility. Using traditional phase shiftingalgorithms, en-face images of a coin have been measured at different depths to illustrate thetomographic capability of this FF-OCT system. In comparison with other current systems,our design has several advantages, and high-resolution high-speed FF-OCT imaging can beenvisioned. The phase shifter can be used for common path setups and is verysuitable for implementing the phase shifting of a broad-spectrum light source.