Detector input can be e.g. @R05046@, @I03255@, @R05039@. It produces a measurable detector output which may be e.g. an electrical charge, an electrical current or potential or a change in pressure. The ratio of the detector output and the detector input is defined as the responsivity. It is given in e.g. @A00300@/@W06656@, @V06634@/@W06656@. The responsivity is a special case of the general term @S05606@. Dark current is the term for the electrical output of a detector in the absence of input. This is a special case of the general term dark output. For photoconductive detectors the term dark resistance is used. If the responsivity is normalized with regard to that obtained from a reference radiation the resulting ratio is called relative responsivity. For measurements with monochromatic radiation at a given @W06659@ the term @S05829@ \(R(\lambda)\) is used. In some cases the @R05279@, where the @S05829@ is normalized with respect to the responsivity at some given @W06659@, is used. The dependence of the @S05829@ on the @W06659@ is described by the spectral responsivity function. The useful spectral range of the detector should be given as the @W06659@ range where the relative responsivity does not fall below a specified value.