Holographic optical coherence imaging of diffuse targets is an en face direct imaging modality that simultaneously illuminates and detects several hundred spatial modes. The interferences among these modes contain information on long-range structure. By using Fourier spatial filtering in Fourier-domain holography, we demonstrate the first phase-contrast en face imaging of extended tissue. This ability represents a fundamental difference between holographic optical coherence imaging (OCI) and conventional optical coherence tomography (that illuminates only a single spatial mode at a time). Channel cross-talk is separated into "interesting" speckle that carries information on long-range spatial coherences in tissue, and "uninteresting" speckle that arises from multiple scattering. Spatial coherence control of the illuminating beam can separate these two contributions. Data on multicellular tumor spheroids obtained from Fourier-domain OCI operating in a phase-contrast mode, using the knife-edge technique, are presented. We achieve -95 dB of sensitivity and nearly 50 dB of dynamic range in tissue reflection.

Date Published: 13 April 2005
PDF: 10 pages
Proc. SPIE 5690, Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine IX, (13 April 2005); doi: 10.1117/12.590080

Published in SPIE Proceedings Vol. 5690:
Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine IX
Valery V. Tuchin; Joseph A. Izatt; James G. Fujimoto, Editor(s)