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The n(λ) and k(λ) spectra of each film are obtained along with film thickness, over a wide range of wavelengths from deep ultraviolet to near infrared wavelengths (190–1000 nm). In the following examples, the notation for theoretical and measured reflectance in the spectral plots is expressed as "R-theor" and "R-meas", respectively.
Many commercial instruments for UV/vis spectroscopy are capable of recording spectra in the NIR range (to perhaps ~900 nm). In the same way, the range of some mid-IR instruments may extend into the NIR. In these instruments, the detector used for the NIR wavelengths is often the same detector used for the instrument's "main" range of interest.
An infrared spectroscopy correlation table (or table of infrared absorption frequencies) is a list of absorption peaks and frequencies, typically reported in wavenumber, for common types of molecular bonds and functional groups.
"Green" Band 3 (559 nm) and "NIR" Band 8A (864 nm) McFeeters index: If looking for water bodies or change in water level (e.g. flooding), then it is advisable to use the green and NIR spectral bands [18] or green and SWIR spectral bands. Modification of normalised difference water index (MNDWI) has been suggested for improved detection of open ...
Karl Norris pioneered the field of near-infrared spectroscopy. [23] He began by using log(1/ R ) as a metric of absorption. While often the samples examined were “infinitely thick”, partially transparent samples were analyzed (especially later) in cells that had a rear reflecting surface (reflector) in a mode called "transflectance".
Radiance emitted by a surface, divided by that emitted by a black body at the same temperature as that surface. Spectral directional emissivity: ε Ω,ν ε Ω,λ — Spectral radiance emitted by a surface, divided by that of a black body at the same temperature as that surface. Hemispherical absorptance: A —
Values of range from below 25 for very dense flint glasses, around 34 for polycarbonate plastics, up to 65 for common crown glasses, and 75 to 85 for some fluorite and phosphate crown glasses. Most of the human eye's wavelength sensitivity curve, shown here, is bracketed by the Abbe number reference wavelengths of 486.1 nm (blue) and 656.3 nm (red)
The near-infrared (NIR) window (also known as optical window or therapeutic window) defines the range of wavelengths from 650 to 1350 nanometre (nm) where light has its maximum depth of penetration in tissue. [1] Within the NIR window, scattering is the most dominant light-tissue interaction, and therefore the propagating light becomes diffused ...