Quasi-single shot axial-lateral parallel time domain optical coherence tomography with Hilbert transformation

We developed axial-lateral parallel time-domain optical coherence tomography (ALP TD-OCT) from a single interference image. A two-dimensional camera can produce a depth-resolved interference image using diffracted light as the reference beam and a linear illumination beam without any mechanical scan. An OCT image of biological tissues with sufficient sensitivity requires extraction of interference signals by subtracting the DC image, which contains the intensity of noninterference light and the electrical noise of the camera, from a single interference image and subsequent application of the Hilbert transformation for each axial direction. We measured 300 interference images of a moving human finger in vivo using an indium gallium arsenide (InGaAs) camera (320 x 250 pixels) operating at 60 frames per second and then obtained OCT images with an imaging range of 5.0 x 1.7-mm(2) (lateral x axial) using a DC image based on averaged interference images. The system sensitivity was 90.5 dB with a 1.05-ms exposure. As the OCT image depends on the interference signals in a single interference image, the OCT signals were stable compared with OCT images based on the phase-shift method.