Abstract: A light source includes an electrodeless lamp having an envelope for enclosing a volatile fill material which emits light upon vaporization and excitation, a source of power at a high frequency and a termination fixture coupled to the source. The fixture has inner and outer conductors which have dimensions such that the lamp is located in the high field region at the end of the conductors. When the high frequency power is applied to the fixture, a voltage standing wave is formed which initiates vaporization and excitation of the fill material. The termination load impedance which is that of the lamp changes from a lossy open circuit to a finite value when vaporization and excitation occur. An impedance matching device is provided for matching the running lamp impedance to the output impedance of the source.

Abstract: A termination fixture for an electrodeless lamp has dimensions which match the output impedance of a coupled high frequency power source to the real impedance of the lamp when in a discharge condition. The fixture may consist of a pair of coaxial conductors, and the lamp forms the termination load for the ends of the conductors. The length of the conductors is such as to place the lamp one quarter wavelength from the opposite ends of the conductors. The diameters of the conductors are such as to produce a fixture characteristic impedance which matches the lamp impedance to the source output impedance.

Abstract: Photographic flash apparatus having one flash unit which may be called the main or master or primary flash unit, and one or more additional flash units which may be called secondary or slave or dependent units. Eliminating connecting cables often used in the prior art, and also eliminating ratio frequency controls sometimes used in the prior art relating to multiple units, the secondary or dependent units of the present invention are independently powered and are triggered to initiate a flash by the light from the flash of the main unit, and triggered to terminate or discontinue the flash in each dependent unit when the flash in the main unit turns off. The control of each secondary unit is entirely by means of the flash of light from the main unit. The apparatus is particularly useful in studio lighting where it is desired to illuminate the subject being photographed from a plurality of different directions.

Abstract: The operating condition of a producer of intermittent radiation, such as a motion-picture projector or a television receiver, is monitored by a detector circuit including a photoelectric transducer followed by a filter with a pass band centered on the interruption frequency. The detector output is used to control the lighting of a lamp or the drawing of a curtain in a room where ambient illumination is to be suppressed or reduced during operation of the monitored apparatus. In one embodiment, the band-pass filter is inserted in a negative-feedback loop which suppresses the frequencies falling within its pass band. A band-stop filter may be connected in cascade with the band-pass filter to block the passage of signals due to other radiation such as ambient artificial light.