Signal detection with a laser amplifier

The use of signal-to-noise ratio as a figure of merit for a signal detection system involving a threshold detector may lead to erroneous conclusions when the signal strength, in absolute terms, is small. Recourse to approximate or exact distributions must be made and the notion of statistical separation must be employed. A new figure of merit utilizing the idea of statistical separation is defined. The method is applied to the question of the efficiency of a laser amplifier in a pulse detection system.