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2 March 2011 Angular-domain imaging of fluorescence sources within tissue phantoms
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Conventional fluorescence imaging often does not have a mechanism to remove the scattering effect in biological tissue. We use Angular Domain Imaging (ADI) to improve the detection of smaller structures in fluorescence layer over that can be provided by existing systems. ADI is a high resolution, ballistic imaging method that utilizes the angular spectrum of photons to filter multiple-scattered photons and accepts only photons with small angular deviation from their original trajectory. Advantages of the ADI technique are that it is insensitive to wavelength and the sources are not required to be high quality, coherent, or pulse, as with OCT or time domain. Our target is to perform fluorescence ADI at shallow tissue such as skin (≈ 1mm) with a buried collagen layer. To experimentally model shallow tissue with phantoms, a thin layer of scattering medium with similar scattering characteristic (μs = 200cm-1, g = 0.85) is placed on top fluorescence plastic (415nm excitation, ≈ 555-585nm emission) which is patterned by strips of non-emitting structures (200-400μm). Positioning multiple collimated arrays with acceptance angles of 5.71° on top of the scattering medium, test structures (200μm wide) can be detected at shallow scattering medium thickness (1mm). Monte Carlo simulation confirms that fluorescence ADI can image structures at shallow tissue depth by using collimator array with modest filtration angles. Results show micromachined collimator arrays provide both high spatial resolution and angular filtration on scattered photons.
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Rongen L. K. Cheng, Polly Tsui, Glenn H. Chapman, Reza Qarehbaghi, and Nick Pfeiffer "Angular-domain imaging of fluorescence sources within tissue phantoms", Proc. SPIE 7897, Optical Interactions with Tissue and Cells XXII, 78970W (2 March 2011);

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