The overall goal of this study is to develop a novel optical coherence photorefractive holographic imaging system that can achieve fast, depth-resolved en-face imaging at different near infrared wavelengths and provide a new tool to assess tissue and cell function and morphology in situ. This is the first demonstration system using photorefractive polymer composites for high-resolution imaging of biomedical tissues. The proposed system has potential advantages such as parallel en-face,imaging without lateral scanning, high sensitivity, large dynamic range, and flexibility of imaging at different wavelengths. In this parallel holographic imaging system, low time-coherence light source in the near infrared region is used. The axial resolution is determined by the coherence length of the source. When the optical path lengths of the reference beam and the backscattered light from the object are matched to within the coherence length, the hologram can be recorded and reconstructed. The photorefractive material can optically reject the multiply scattered light, allowing large dynamic range. In each step, a 2D en-face cross-sectional image can be obtained in parallel. By translating the object, slices of en-face images for different depth are formed with a fast response photorefractive material, and a 3D volume can be recontructed in real-time by computer rendering. In the proposed exploratory phase of this technology-driven project, we will evaluate the performance of our novel imaging systern on tissue phantoms and biologically relevant samples ex-vivo. We will compare the obtained images to images in non-scattering media and to cross sectional microscopy images of our samples after standard histologic processing. Success of the experiments would be demonstrate if we can resolve 40.3 lines per mm below 100 micron of medium with a scattering coefficient of 100 cm^-1. Successful completion of this project will include the design a specific medical/clinical application suitable for a R33 phase.
