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9 July 2009 Angular domain optical imaging of turbid media using enhanced micro-tunnel filter arrays
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We experimentally characterized the angular distribution and proportion of minimally deviated quasi-ballistic (snake) photons versus multiply scattered photons in a homogenous turbid medium. The study examined the angular distribution of photons propagating through and exiting the highly scattering medium over a narrow range about the axis of a collimated light source in trans-illumination mode. The measurements were made using an angular domain imaging system that employed one of five silicon micro-machined arrays of micro-tunnels each with a range of different acceptance angles and micro-tunnel structures. The balance between quasi-ballistic photons and unwanted multiply scattered photons accepted by the micro-machined angular filters was measured in order to determine the optimum range of acceptance angles for the system. The experiments were performed in tissue mimicking phantoms using a 2-cm thick optical cell with 0.25% IntralipidTM and a near infrared laser. This paper also presents experimental results of the angular domain imaging system employing novel micro-tunnel arrays with minimal internal reflection which can accept the non-scattered light exiting from the turbid medium within its small acceptance angle more efficiently. Our experiments reveal that image contrast was improved from 20% to 30% by employing an angular filter array with minimal internal reflection compared to conventional square-shaped filter arrays of identical size.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fartash Vasefi, Benny S. L. Hung, Bozena Kaminska, Glenn H. Chapman, and Jeffrey J. L. Carson "Angular domain optical imaging of turbid media using enhanced micro-tunnel filter arrays", Proc. SPIE 7369, Diffuse Optical Imaging II, 73691N (9 July 2009);

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