ABSTRACT
In Fourier domain (FD) optical coherence tomography (OCT), the
interference pattern is recorded as a function of light frequency
which can either be encoded spatially with the help of a diffraction
grating and a camera or be encoded in time using a sweeping
frequency laser source. FD-OCT systems typically have a sensitivity
advantage of about 20-30 dB over the conventional time domain
(TD) OCT systems [1, 2]. The sensitivity advantage of FD-OCT
and possibility to enhance imaging speed by parallelization has
motivated researchers to develop line field (LF) FD-OCT and
swept source (SS) full-field (FF) OCT imaging techniques. The
LF-FD-OCT setup typically consists of a Michelson interferometer
with an anamorphic illumination system using a broadband light
source to produce a line illumination on the sample and the
reference mirror. The light reflected from the sample and the
reference arm is combined and dispersed using a diffraction
grating, and subsequently detected by a 2D charge-coupled device
(CCD)/complementary metal-oxide semiconductor (CMOS) camera.
Thus, a spectrally resolved interference signal of each point on the
line illuminating the sample is obtained in parallel. A simple 1D
fast Fourier transformation (FFT) along the spectral dimension of
the data (after λ → k interpolation) yields an XZ cross-sectional image. A working LF-FD-OCT system was first demonstrated by
Zuluaga and Richard-Kortum using a technical sample [3]. This
technique has been further developed by Grajciar et al. [4] and
Nakamura et al. [5] for in vivo ophthalmic imaging. However, this
technique still requires scanning along one lateral direction in order
to acquire 3D volume image. On the other hand, SS-FF-OCT does
not require scanning of the sample in any direction. The FF-SS-
OCT setup usually consists of a free-space Michelson interferometer
and involves area illumination with a sweeping wavelength laser
source on the sample and the reference mirror. The detection of
the generated interference signal is performed by a high-speed 2D
camera. The 2D interference signal is recorded for each wavelength
sequentially in time, and 1D FFT (after λ → k interpolation) is performed along the spectral dimension to get a 3D volume image
with depth information of the sample.
