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.