title: Lensed fiber-optic probe design for efficient photon collection in scattering media.
abstract: Measurement of bioluminescent or fluorescent optical reporters with an implanted fiber-optic probe is a promising approach to allow real-time monitoring of molecular and cellular processes in conscious behaving animals. Technically, this approach relies on sensitive light detection due to the relatively limited light signal and inherent light attenuation in scattering tissue. In this paper, we show that specific geometries of lensed fiber probes improve photon collection in turbid tissue such as brain. By employing Monte Carlo simulation and experimental measurement, we demonstrate that hemispherical- and axicon-shaped lensed fibers increase collection efficiency by up to 2-fold when compared with conventional bare fiber. Additionally we provide theoretical evidence that axicon lenses with specific angles improve photon collection over a wider axial range while conserving lateral collection when compared to hemispherical lensed fiber. These findings could guide the development of a minimally-invasive highly sensitive fiber optic-based light signal monitoring technique and may have broad implications such as fiber-based detection used in diffuse optical spectroscopy.
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea ; Co-first authors with equal contribution.
authors: Youngjae
authors: Y
authors: Ryu
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea ; Co-first authors with equal contribution.
authors: Younghoon
authors: Y
authors: Shin
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea.
authors: Dasol
authors: D
authors: Lee
authors: Metabolic Disease Program, Sanford-Burnham Medical Research Institute, USA.
authors: Judith Y
authors: JY
authors: Altarejos
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea ; Department of Mechatronics, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea ; Co-corresponding authors: ogong50@gist.ac.kr.
authors: Euiheon
authors: E
authors: Chung
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea ; Department of Mechatronics, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea.
authors: Hyuk-Sang
authors: HS
authors: Kwon
keywords: (000.4430) Numerical approximation and analysis; (060.2300) Fiber measurements; (170.3660) Light propagation in tissues; (170.5280) Photon migration; (170.7050) Turbid media
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