Times required for the detection of a target on a simulated PPI scope were determined for various scope luminances after different durations of light adaptation to a luminance of 3100 millilamberts. Increased duration of light adaptation results in increased detection time up to a maximum value which varies with scope luminance. In general, detection time decreases with either an increase in target luminance or a decrease in background luminance for a given duration of light adaptation. Within the range of luminances investigated, changes in target luminance result in a greater change in detection time than comparable changes in background luminance. The implication for radar scope viewing after adaptation to a high luminance is that optimum visibility will be obtained with maximum gain and as much negative bias as is possible without appreciable reduction of target luminance.
JOHN L. BROWN, A. LEONARD DIAMOND, and AND HELMUT E. ADLER, "Effect of Duration of Light Adaptation on Time Required for Detection of a Target on a Simulated PPI Scope," J. Opt. Soc. Am. 43, 1147-1152 (1953)