| 摘要 |
An infra-red auto-ranging system for a photographic camera or the like includes a ranging sensor that directs a portion of the light energy from the subject of principal interest through a diffraction device that diffracts the radiation into central and higher order spectral lines that are then passed through an infra-red filter. An infra-red responsive sensor, such as a photo-responsive reticon array, is positioned to receive the radiation from a selected one of the spectral lines with the position of the imaged spectral energy on the sensor varying as a function of the angle of incidence of the light from the subject and of the range to the subject. The diffraction device may take the form of a conventional transmission-type diffraction grating, a replica, or an acousto/optical diffraction cell responsive to an excitation energy source. Computing circuitry is provided to determine the range to the subject of principal interest as a function of the position that the selected spectral line images on the sensor. By appropriate selection of the diffraction characteristics of the diffraction device, it is possible to limit the width of the selected spectral line to a narrowly defined physical limit to enhance the resolution of the ranging determination.
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