Range resolution enhancements for laser radar by phase modulation

Abstract

A technique is developed to increase the range resolving ability of a long pulse laser radar system. Range resolution is the ability to distinguish between two or more closely spaced objects. The resolving ability of a pulsed ladar system is related to the effective correlation bandwidth of the pulse. Phase modulation of an outgoing pulse increases the effective correlation bandwidth of the pulse and enhances range resolution. Using a coherent, pulsed ladar system a pulse would be emitted from the system and the return signal detected. The return pulse is optically heterodyned and recorded. The recorded echo is then matched filtered to obtain an estimate of range. The estimate will be shown to have increased resolution with modulation.