Complex Conjugate Resolved Retinal SDOCT using Integrating Buckets

摘要

The complex conjugate artifact intrinsic to spectral domain optical coherence tomography (SDOCT) complicates retinal image acquisition in patients with poor fixation or head control, imaging of vitreal and choroidal structures, and imaging of extended retinal pathologies. We demonstrate high speed complex conjugate artifact-resolved imaging of human retina using simple and inexpensive sinusoidal reference mirror modulation in combination with 4-step integrating-bucket acquisition and a quadrature projection reconstruction algorithm. The method uses a sinusoidal PZT driving signal to modulate the reference delay continuously during N integration buckets per modulation. The spectral interferometric signal measured by the CCD is phase shifted as a function of the amplitude and phase offset of the driving signal. We show that the amplitude and phase can be optimized for DC and complex conjugate artifact removal and minimal fringe washout. This method is illustrated experimentally using a four bucket phase modulating signal and quadrature projection algorithm for complex conjugate suppression. DC suppression of 53dB and complex conjugate suppression of 30dB is demonstrated for sets of four A-scans, each acquired at 17kHz. Densely sampled (3000 A-scans/image, acquired at 1.46 images/sec) in vivo complex conjugate artifact-resolved images of fovea and optic nerve-head acquired show complex conjugate artifact suppression for most image reflections to the noise floor.