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.
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