Spectral-domain OCT with dual illumination and interlaced detection for simultaneous anterior segment and retina imaging

Abstract

We present Fourier-domain/spectral-domain optical coherence tomography (FD/SD-OCT) using a single spectrometer with dual illumination and interlaced detection at 830 nm, which can provide anterior segment and retinal tomograms simultaneously. Two orthogonal polarization components were used so that both parallel and focused beams could simultaneously be made incident on the eye. This configuration with a polarization-separated sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample information. In the detector arm, a single spectrometer is illuminated via an ultrafast optical switch for interlaced detection. A graphical user interface (GUI) was built to control the optical switch for imaging the anterior segment and retina either simultaneously or individually. In addition, we implemented an off-pivot complex conjugate removal technique to double the imaging depth for anterior segment imaging. The axial resolution of our FD/SD-OCT system was measured to be ~6.7 μm in air, which corresponds to 4.9 μm in tissue (n = 1.35). The sensitivity was approximately 90 dB for both anterior segment and retina imaging when the acquisition speed was 35,000 A-scans per second and the depth position was near 120 μm from the zero-depth location. Finally, we demonstrated the feasibility of our system for simultaneous in vivo imaging of both the anterior segment and retina of a healthy human volunteer.