Opacity (optics)

Opacity Definition and Characteristics

Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light.
It describes the absorption and scattering of radiation in a medium.
An opaque object is neither transparent nor translucent.
Light striking an interface between substances can be reflected, absorbed, scattered, or transmitted.
Opacity depends on the frequency of the light being considered.

Radiopacity is used to describe the opacity of X-rays.
Radiodense substances do not allow X-rays or similar radiation to pass through.
Radiodense contrast media revolutionized radiographic imaging.
Radiopacity is a key consideration in the design of medical devices used during radiological intervention.
It allows the tracking of devices during procedures.

Opacity has a specific, quantitative definition used in astronomy, plasma physics, and other fields.
It is synonymous with the mass attenuation coefficient or mass absorption coefficient.
Opacity is measured at a particular frequency of electromagnetic radiation.
In air pollution work, opacity refers to the percentage of light blocked.
Opacity can vary from 0% light blocked to 100% light blocked.

Planck opacity uses the normalized Planck black-body radiation energy density distribution as the weighting function.
Rosseland opacity uses the temperature derivative of the Planck distribution as the weighting function.
Photon mean free path is the inverse of the Rosseland opacity.
The Rosseland opacity is derived in the diffusion approximation to the radiative transport equation.
The mean opacity for Thomson electron scattering and nonrelativistic thermal bremsstrahlung can be calculated.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/opacity-optics
Wikipedia	http://en.wikipedia.org/wiki/Opacity_(optics)
Wikidata	https://www.wikidata.org/wiki/Q691914
Knowledge Graph	https://www.google.com/search?kgmid=/m/09myyn