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This page was last edited on 18 November 2013, at 15:41 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.
Optical density is a result of the darkness of a developed picture and can be expressed absolutely as the number of dark spots (i.e., silver grains in developed films) in a given area, but usually it is a relative value, expressed in a scale. [citation needed]
AFAIK, optical density was originally defined by Hurter and Driffield as D = log10(O) to indicate the amount of an opaque substance suspended in a transparent medium: "For our purposes, i.e., in its application to negatives, the density is directly proportional to the amount of silver deposited per unit area, and may be used as a measure of ...
τ ν is the spectral optical depth in frequency, and; τ λ is the spectral optical depth in wavelength. Although absorbance is properly unitless, it is sometimes reported in "absorbance units", or AU. Many people, including scientific researchers, wrongly state the results from absorbance measurement experiments in terms of these made-up ...
The constant of proportionality μ was often termed the "optical density" of the body. As long as μ is constant along a distance d , the exponential attenuation law, I = I 0 e − μ d {\displaystyle I=I_{0}e^{-\mu d}} follows from integration.
A densitometer is a device that measures the degree of darkness (the optical density) of a photographic or semitransparent material or of a reflecting surface. [1] The densitometer is basically a light source aimed at a photoelectric cell . [ 2 ]
In photography and optics, a neutral-density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving no changes in hue of color rendition.
The volume fraction of porosity had to be reduced below 1% for high-quality optical transmission (99.99 percent of theoretical density). This goal has been readily accomplished and amply demonstrated in laboratories and research facilities worldwide using the emerging chemical processing methods encompassed by the methods of sol-gel chemistry ...