| 摘要 |
A cylindrical objective lens 10 views a field of view within which a source of radiation may be located. The objective lens 10 produces a line image on a mask 11 located in the focal plane of the objective lens. The mask carries a number of parallel tracks extending perpendicular to the line image, each track comprising a sequence of opaque and translucent regions. Optical means comprising further cylindrical lenses 13, 14, 15 are provided to image the illuminated portions of the tracks on the mask 11 on to a linear array of detectors 12. Circuit means are provided which respond to the electrical outputs of the detectors to provide an indication of the direction of the source relative to a datum direction. The mask tracks may form a Gray code and further tracks may be provided to guard against illumination by a source of large angular subtense or incomplete illumination of the mask providing a false indication. A second similar apparatus may be modified to provide an indication of wavelength (figure 4, not shown). |
