# Lambert's cosine law

In

telecommunication,

**Lambert's cosine law** is the mathematical statement that the radiance of certain idealized optical sources is

directly proportional to the cosine of the angle--with respect to the direction of maximum radiance--from which the source is viewed.

*Note:* Lambert's cosine law may also apply to certain idealized diffuse reflectors. *Synonyms* **cosine emission law, Lambert's emission law.**

Source: from Federal Standard 1037C