Design of a spectrometer for all-reflective optics-based line scan Fourier domain optical coherence tomography

Abstract

Optical design of a spectrometer for all-reflective optics based line scan Fourier domain optical coherence tomography (FD-OCT) imaging has been reported in this work for high-speed scanning. FD-OCT imaging data acquisition offers significantly improved imaging speed in the depth direction compared to conventional time domain optical coherence tomography (TD-OCT). On the other hand, line focused scanning improve imaging speed in the transverse direction compare to commonly used flying spot scanning. Combination of FD-OCT acquisition and line focused scanner can give higher imaging speed. Spectrometer is a critical submodule in FD-OCT system. Apart from the spectrometer optical resolution, and detector array resolution, the chromatic aberration should be considered to design a high-quality FD-OCT imaging spectrometer. The proposed imaging spectrometer consists of a planer reflective grating, off-axis parabolic cylindrical mirror and a CCD array detector. Mirror focusing reduces the chromatic aberration because of its insensitivity to the wavelength of the laser beam, therefore the spectrometer image quality enhanced by the reflective optics focusing. Spot profile fall-off characteristic was analyzed by using ZEMAX optical design software.