Photonics Dictionary: R

The fundamental wavelength standard of time or frequency. An atomic standard, it is properly expressed as 9,192,631,770 times the frequency of the transition between the hyperfine structure levels of...

Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that allows for high-resolution, in vivo imaging of biological tissues at the cellular level. It is particularly useful in...

1. In optics, the ability of a lens system to reproduce the points, lines and surfaces in an object as separate entities in the image. 2. The minimum adjustment increment effectively achievable by a...

The re-emission of absorbed energy, having the same wavelength as the incident energy, in an arbitrary direction from a particle because of an energy level transition within the material.

That radiation emitted by an atom or molecule that has the same frequency as that of an incident particle; e.g., a photon. It generally involves a transition to the lowest energy level of the atom or...

A test method for determining high-reflectivity levels by monitoring cavity decay within a resonant cavity formed by two mirrors under test.

One of the types of change in the energy levels of molecules or atoms in a laser that can result in lasing action. Because the energy levels between rotational states are small, such lasing action is...

A digital imaging method whereby the first gray level in the ordered sequence and the position of the first lengths of all runs are specified; used when there are only two possible gray levels...

A digital imaging method whereby the first gray level of each sequential point-by-point sample and its position in the succession of gray levels is encoded. It is used when there is a tendency for...