The rayleigh, originally defined as a unit to express the total column light emission rate [1010 photons sec−1 (m2column)−1] can equivalently be defined as a unit for apparent photon radiance (1/4π 1010 photons sec−1 m−2 sr−1). The selection of the appropriate definition will depend upon the physical situation and the interests of the user. The applicability of the unit for expressing the quantitative measurement of all extended light sources, including optically thick media, is both handy and valid.
© 1976 Optical Society of America
Original Manuscript: March 8, 1976
Published: August 1, 1976
Doran J. Baker and Gerald J. Romick, "The rayleigh: interpretation of the unit in terms of column emission rate or apparent radiance expressed in SI units," Appl. Opt. 15, 1966-1968 (1976)