Specific detectivity

Specific detectivity: For a photodetector[?], a figure of merit used to characterize performance, equal to the reciprocal of noise equivalent power (NEP ), normalized to unit area and unit bandwidth.

Note: Specific detectivity[?], D *, is given by where A is the area of the photosensitive region of the detector and Δf is the effective noise bandwidth. Synonym D-Star.

Source: from Federal Standard 1037C