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Characteristic Length and Time Scales of the Highly Forward Scattering of Photons in Random Media
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| Title: | Characteristic Length and Time Scales of the Highly Forward Scattering of Photons in Random Media |
| Authors: | Fujii, Hiroyuki Browse this author →KAKEN DB | | Ueno, Moegi Browse this author | | Kobayashi, Kazumichi Browse this author →KAKEN DB | | Watanabe, Masao Browse this author →KAKEN DB |
| Keywords: | radiative transfer equation | | highly forward scattering of photons | | diffusion and delta-Eddington approximations | | characteristic length and time scales of photon transport |
| Issue Date: | 20-Dec-2019 |
| Publisher: | MDPI |
| Journal Title: | Applied Sciences |
| Volume: | 10 |
| Issue: | 1 |
| Start Page: | 93 |
| Publisher DOI: | 10.3390/app10010093 |
| Abstract: | Background: Elucidation of the highly forward scattering of photons in random media such as biological tissue is crucial for further developments of optical imaging using photon transport models. We evaluated length and time scales of the photon scattering in three-dimensional media. Methods: We employed analytical solutions of the time-dependent radiative transfer, M-th order delta-Eddington, and photon diffusion equations (RTE, dEM, and PDE). We calculated the fluence rates at different source-detector distances and optical properties. Results: We found that the zeroth order dEM and PDE, which approximate the highly forward scattering to the isotropic scattering, are valid in longer length and time scales than approximately 10/μ′t and 40/μ′tv, respectively, where μ′t is the reduced transport coefficient and v the speed of light in a medium. The first and second order dEM, which approximate the highly forward-peaked phase function by the first two and three Legendre moments, are valid in the longer scales than approximately 4.0/μ′t and 6.3/μ′tv; 2.8/μ′t and 3.5/μ′tv, respectively. The boundary conditions less influence the length scales, while they reduce the times scales from those for bulk at the longer length scale than approximately 4.0/μ′t. Conclusion: Our findings are useful for constructions of accurate and efficient photon transport models. We evaluated length and time scales of the highly forward scattering of photons in various kinds of three-dimensional random media by analytical solutions of the radiative transfer, M-th order delta-Eddington, and photon diffusion equations. |
| Rights: | https://creativecommons.org/licenses/by/4.0/ |
| Type: | article |
| URI: | http://hdl.handle.net/2115/76547 |
| Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 藤井 宏之
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