| 摘要 |
1,158,863. Photo-electric direction finders. SOC. ANON DE TELECOMMUNICATIONS. 29 July, 1966 [6 Aug., 1965], No. 34089/66. Heading H4D. Relates to photo-electric direction finders in which the frequency modulation produced by a rotating reticle 5 composed of alternate obturating and non-obturating sectors is rotated in the focal plane of the objective 2. According to the present invention a graded optical filter 11 is added near that focal plane, the opacity is a minimum at the centre of the filter and increases progressively outwards therefrom, a second system incorporating a similar reticle 15 driven at the same speed as, and in phase with, reticle 5 is provided, and the outputs of photo-cells 9 and 17 are differentially combined before demodulation in known circuit 10. It is stated that background interference from objects near the light source whose direction is to be ascertained, is reduced. The second system may incorporate an obturator 19 and the field of view of the second system may be made the larger, Fig. 2 (not shown). |
