GB191509543A - Improvements relating to Apparatus for Signalling by Means of Light. - Google Patents

Abstract

9543. Brodsky, G. June 30. [Cognate Application, 11,423/15.] Flash signals; recording signals.-Flash signals are given by a beam of polarized light, the polarizer at the transmitting station being rotated through a right-angle to produce variations in intensity of the light when viewed through an analyzer, or variations in the observed colour may be obtained by interposing a filter of mica, quartz, or other doubly-refracting medium in the beam. The polarizer comprises one or more piles of thin glass plates 10, with intermediate partitions 11 to stop reflected light, mounted at a suitable angle in a barrel 3 which is rotatably mounted in a cylindrical casing 2. The polarizer is interposed in the path of a parallel beam of light from any suitable source, such as an electric lamp or heliographic apparatus. The barrel 3 may be rotated to give signals by any suitable means, such as a handle passing through a slot in the casing 2, or Bowden wire attached to a pin 15, and may be returned by a spring. The barrel shown is mounted by means of pivot pins 7 and spiders 6, but circumferential ball-bearings may be substituted. Any suitable analyzer may be used by the observer. The analyzer described comprises a pile or piles of glass plates mounted in a tube, which may, if desired, be attached to a telescope or binoculars. A photographic record of the signals may be made by passing the light through a slit behind the analyzer, on to a moving negative strip. An arrangement is also described in which the light passing through,the analyzer is focussed, by a parabolic mirror, on to a selenium cell in circuit with a telephone or an electro-magnetic relay controlling a. tape telegraph recorder or other indicating device. According to Provisional Specification 9543/15, the plane of polarization may be rotated magnetically, and the apparatus may have sighting arrangements.