Système de détection angulaire

1,136,272. Photo-electric position finding. UNITED AIRCRAFT CORP. 9 Aug., 1966 [13 Aug., 1965], No. 35616/66. Heading H4D. In a photo-electric direction finder a light beam is caused to scan spirally a field of view. The spiral scan is outwardly from the centre and back thereto, the time interval between the two ensuing echo pulses being a measure of the angular position of the target (e.g. a satellite) from the direction of the unscanned beam, Figs. 3, 4 (neither shown). In the embodiment a laser is pulsed and range measurement may be added. The laser Q-switching may be effected using an ultrasonic modulator 18 as described in Specification 1,068,515 (see Division . H1). The spiral scan is produced by an ultrasonic modulator as described in Specification 1,127,238, or 1,136,271. The target may be automatically tracked. The angular measurement is obtained from an oscilloscope 32 or a computer 34. Telescope 16 may be eliminated by beam splitting optics in telescope 14; or the latter may be omitted. A continuous-wave laser may be utilized, the ambiguity in consecutively received pulses being resolved by a reference marker generated at the beginning of each spiral scan.