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Definition: a term mostly used in a qualitative way, related to the output power and beam quality of a laser; quantitatively: often used instead of radiance or luminance

German: Helligkeit, Leuchtdichte

Category: general optics

How to cite the article; suggest additional literature


The term brightness should be used only for non-quantitative references, e.g. in the context of physiological sensations; that is recommended by the U.S. Federal Standard 1037C, for example. For actual quantitative references, one should usually use one of the following terms:

Unfortunately, the term brightness is often somewhat inaccurately used instead of radiance or luminance.

In laser technology, the term brightness is often said to be higher for one type of laser than for another, for example, but rarely with an actual quantitative specification (some numbers and units). What is usually meant is the clearly defined term radiance. That implies e.g. that the brightness of a laser is increased if its beam quality is improved for a fixed output power level.

The term also occurs as part of composite terms:

See also: spectral brightness, radiometry, lasers, brightness converters, beam quality, diffraction-limited beams, laser design, high brightness laser diodes
and other articles in the category general optics


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