Journal of the Society of Motion Picture and Television Engineers (1950-1954)

camps267 of France. An interference mirror used in an arc projector to transmit infrared and reflect the visible spectrum was described by Koch.268 The use of the electrooptical shutter has been applied by Babits and Hicks of Rensselaer,269 using ADP crystals, for the production of electrically controlled color filters. S. Light Sources A number of interesting light sources and their applications were described in 1950. A high-intensity spark source, providing an effective duration of the order of 10"7 sec has been developed at Catholic University.270 The system used permits a much more intense source than has been previously developed. The light emission from high-current spark discharges of the flash-tube type, has been studied by Glaser.271'272 Sparks obtained with the discharge of the large capacitances (0.01 to 5 mf at 2 to 15 kv) through gases at 1 to 17 atm were studied for spectral emission. Additionally, oscillator discharges were studied. The FT-110 flash tube providing for high efficiency at low voltage was described by Noel and Davis.273 Barstow98 applied a very small quartz tube designed specifically for an infrared instrument recorder. The use of the gaseous-discharge tube as a light source for motion pictures was analyzed by Carlson and Edgerton,274 while Olsen and Huxford275 of Northwestern University measured the electrical and radiation characteristics of flash discharges in quartz tubes filled with rare gases at pressures of about 100 mm of mercury. Laporte has applied xenon flash tubes to photomicrography at repetition rates up to 25/sec,276 and has investigated277 the use of the gaseous-discharge tube for projection at 24 frame/sec, a flash tube operating at 48 flashes/sec has been employed. An embodiment of this nature was described in a German journal by Hagemann278 in a continuously moving film projector. A compact source lamp described by Bourne and Beeson279 has been employed for high-speed motion picture photography. This device, named the Cine Flash, permits the flashing of two compact source mercury-cadmium lamps operated in series at their normal wattages of 1 kw as continuous sources, and then flashed at 3, 5 or 10 kw for 5, 2 or 1 sec. This light output is sufficient for color photography at speeds up to 3000 frame/sec or for black-and-white photography with small lens apertures to give considerable depth of focus. General Electric introduced a schlieren light source utilizing their H-6 mercury lamp.280 Hoyt and McCormick281 have made an intensive study of the dependence of peak intensity and duration of the visible light from arcs of a few microseconds' duration in xenon, krypton and argon on the input energy, the circuit characteristics, the gas and the pressure. The ultraviolet radiation of the high-pressure xenon arc was investigated by Baum and Dunkelman.282 This source, operating under a pressure of approximately 20 atm, provides a particularly intense ultraviolet source. It was found that the radiance of the central spot exceeds that of the carbon crater by a factor of 23 at 2500 A, 12 at 3000 A, and 6 at 3500 A. Carbon arcs have been the subject of further research, and have led to the development of a new high-intensity carbon arc lamp described by Gretener.283 This device, called the Ventarc, produces an extremely high brilliance. A power supply for the Western Union concentrated arc lamp was described by Mitchell,284 and Buckingham285 disclosed the new Western Union open-air concentrated arc lamp. This latter device, using molten zirconium, provides an intense light source of small size, relatively long life, and good stability. T. Nuclear With the advent of the new nuclear emulsions produced by Kodak here and Kenneth Shaftan: Photographic Instrumentation in 1950 475