page_title: Near-infrared window in biological tissue
section_title: Fat
hierarchical_section_title: Near-infrared window in biological tissue / Absorption properties of tissue components / Fat
caption_attribution_description: English: fig_5
context_page_description: The near-infrared window defines the range of wavelengths from 650 to 1350 nanometre where light has its maximum depth of penetration in tissue. Within the NIR window, scattering is the most dominant light-tissue interaction, and therefore the propagating light becomes diffused rapidly. Since scattering increases the distance travelled by photons within tissue, the probability of photon absorption also increases. Because scattering has weak dependence on wavelength, the NIR window is primarily limited by the light absorption of blood at short wavelengths and water at long wavelengths. The technique using this window is called NIRS. Medical imaging techniques such as fluorescence image-guided surgery often make use of the NIR window to detect deep structures.
context_section_description: Fat is one of the major components in tissue that can comprise 10-40% of tissue. Although not many mammalian fat spectra are available, Figure 4 shows an example extracted from pig fat.
caption: Figure 5: The scattering coefficient spectrum of biological tissue.[10]
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