According to an embodiment, an interrogator includes a beam generator operable to scan a variable-power beam across a field of view, a detector aligned to receive an electromagnetic signal from the field of view and generate a corresponding detection signal, and a controller operatively coupled to the detector and the beam generator and operable to vary the power of the beam as it scans across the field of view responsive to the detection signal. According to an embodiment, an illumination system includes an illumination source operable to provide spatially-varying illumination, a detector configured to receive scattered energy from the spatially-varying illumination, and an electronic controller operable to vary the spatial variation of the illumination responsive to the scattered energy received by the detector. According to an embodiment, a method includes illuminating a field of view with a variable power illumination pattern, receiving scattered light from the field of view, and modifying the pattern of the variable power illumination responsive to the scattered light