RQE Spot Detector Needed

Need an RQE detector that provides a very focused detection zone. The small space will be occupied and I do not want the door unlocking when occupants move around or go to the door to see who is knocking. Ideally, the detector would reliably detect a hand reaching for the lever on a mortise lockset. I already know the other techniques (i.e. switch in the lock, foot pad, pushbutton, etc) but I am restricted ONLY in a motion or presence detector.