Transmission by Invisible Rays

Radio Record, Volume III, Issue 27, 17 January 1930, Page 10

Transmission by Invisible Rays

— ee A Modern Invention YEW systems of communication are constantly being sought-to relieve the eongestion of existing channels and to increase the usefulness of communication apparatus, A demonstration was recently given of such a new system, which used ultra-violet light as a medinm over which intelligence could be conveyed. The ultra-violet ray exhibition made apparent immediate scientific usages and opened a wide experimental fiel/. An example is ship-to-ship communication in time of war, when radio sig nals and visible light beams wauld he impractical. The same is true of communication between aeroplanes, In fact, an invisible ray, for the transmission of sound and pietures, which ray can neither be seen nor henrd, has far-reaching potentialities, The demonstration of this new means of communication was recently held in New Yotk, The casual spec tator ohseryed a group of transmitting equipment at one end of the building and a receiving device at the opposite end. A bulb emitted a beam of varying coloured light from the transmitting end. The light flickered and changed in intensity in accordance with the words which an oflicial spoke into a nearby microphone connected to an apparatus operating the bulb, The bulb behaved the same way when attached to the television transmitter, At the opposite end of the floor a loudspeaker and headphones delivered the same speech; or when television -was being sent a sereen showed the image of the person seated before the television transmitter, Whenever the light or rays were intercepted, reception stopped, Following this, a filter allowing ultra-violet rays to pass through was placed over the bulb. Reception of both sound and television still continued, The feasibility of the system is due in large measure to the extraordinary qualities of the mercury induetion lamp, originally developed for therapeutie work, but recently discovered to have desirable characteristics for light modulation beyond the highest frequeney needed for television, A. remarkable feature of this lamp is that the radio frequeney which actuates it eauses it to darken and glow at least thirty million times in every second. i