A special photodetector array for sampling the light energy distribution in a plane, such as the diffraction or fourier-transform pattern of an illuminated object transparency which is obtained by a well-known optical configuration in the rear focal plane of a simple lens. The function of the array, in this diffraction pattern measurement example, is to provide simultaneous and nearly instantaneous voltage readouts corresponding to the power spectral density and to the angular variations in the spatial structure of the input object's pattern. The array comprises first and second semi-circular sub-arrays. The first sub-array comprises a plurality of concentric annular detectors, such as hemi-rings. The second sub-array comprises a plurality of detectors extending approximately radially from near to the center of the first sub-array. Each detector of the array is provided with a separate attached electrical conductor. The conductors attached to the ring detectors are positioned in portions of approximately radial sector gaps separating the two sub-arrays.
PHOTODETECTOR LIGHT PATTERN DETECTOR