Unicell photometer device

摘要

A unicell radiation measuring device having a single electrical output signal that can be correlated with film sensitometric characteristics and scene object luminance patterns to either predict photographic exposures directly, or alternatively, used as an input function for controlling a camera exposure control system. The device consists of an optical system having a single optical element for collecting and directing radiation from a scene onto the surface of a photoelectric transducer element having a spectral sensitivity substantially identical to the photopic visual response curve of the standard photometric observer according to the CIE thereby qualifying it as a photometer. The optical element consists of a central circular planar portion of uniform thickness surrounded by an annular positive lens portion having radially decreasing thickness. Both portions are integrally molded to provide the optical element with a unitary construction that is rotationally symmetric. The optical element functions to provide the device with a preferred directional response pattern that selectively weights the radiation received from objects distributed throughout a scene and also optimizes the transfer function of the device.