steradiancy

English

Noun

steradiancy (countable and uncountable, plural steradiancies)

1. The rate of radiation transfer from a surface for each steradian of solid angle in a specified direction per unit area of cross section of the radiation perpendicular to that direction
   • 1954, Alexander Hollaender, Radiation Biology: Ultraviolet and related radiations, page 123:

     Such sources usually attain brilliance by high current densities in small volumes. The total energy output may therefore be less than a greatly extended source of low steradiancy.

   • 1959, United States. National Aeronautics and Space Administration, NASA Technical Note (issues 3641-3650, page 15)

     The geometry of the cone θ and the irradiance at the image of the carbon block were used to determine the absolute steradiancy of the energy in the cone θ as a radiometer calibration value.

   • 1966, Project Fire Flight 1 Radiative Heating Experiment, page 29:

     […] steradiancies seen by the instrument during calibration were between 45 and 55 percent higher than the calculated average steradiancies […]