Optical domain subsampling for data-efficient optical coherence tomography (OCT)

Abstract

Recent advances in optical coherence tomography (OCT) have led to higher-speed sources that support imaging over longer depth ranges. Limitations in the bandwidth of state-of-the-art acquisition electronics, however, prevent adoption of these advances into clinical applications. This thesis introduces optical-domain subsampling as a method for increasing the imaging range while reducing the acquisition bandwidth. Optically subsampled lasers utilize a discrete set of wavelengths to alias fringe signals along an extended depth range into a bandwidth limited window. By detecting the complex fringe signals and under the assumption of a depth-constrained signal, optical domain subsampling enables recovery of the depth-resolved scattering signal without overlapping artifacts. Key principles behind subsampled imaging will be discussed, as well as the design criteria for an experimental subsampled laser. A description of the laser, interferometer, data acquisition system, and signal processing steps is given, and the results of point spread functions compressed into a baseband window are presented. Images that were taken with the subsampled OCT system and a wide-field microscope show that this imaging scheme is viable in vivo and can advantageously image samples that span a long depth range.