Abstract: An improvement in a semi-active laser last pulse logic missile seeker is disclosed and claimed. In one embodiment, the improvement includes a first polarizer disposed in the detection field of view of the PIN photodiode detector and a second polarizer disposed in the detection field of view of the staring imaging infrared focal plane array. Each of the first and second polarizers has an identically configured plurality of segments. Each segment allows transmission of a different polarization than other segments and is sized to completely cover the fields of view of both the PIN photodiode detector and the staring imaging infrared focal plane array. First and second actuators are connected to the first and second polarizers, respectively, to synchronously and simultaneously step identical and corresponding segments in a plurality of discrete steps within the fields of view in response to incoming temporal and spatial laser returns.

Abstract: The semi-active laser (SAL) last pulse logic seeker utilizing a focal plane array is obtained by combining the semi-active laser last pulse logic sal processing using a single PIN photodiode with a staring imaging infrared (I.sup.2 R) focal plane array detector, such as InSb. The result is an improvement that renders the seeker capable of operating in three different modes: SAL only, I.sup.2 R only or simultaneous multi-spectral processing in SAL/I.sup.2 R. The improvement uses a single PIN photodiode detector with an imaging infrared focal plane array (I.sup.2 R FPA) detector to correlate the temporal laser returns of the former with the spatial laser returns of the latter which enables the SAL last pulse return, indicative of the true target, to be identified on the I.sup.2 R FPA. To facilitate the correlation process, the FPA can be divided into regions-of-interest (ROI) that are analyzed to determine which temporal laser pulse falls in which particular ROI.