The General Radio Strobolux unit triggered by a Strobotac has been used extensively in this laboratory for visual threshold determinations. This photometric study was undertaken to provide information on the duration of the flash and the constancy of the total energy for successive flashes. By using a standardized ribbon filament lamp for a comparison source and four narrow pass filters, the total energy per flash in absolute units was found for four spectral regions. A high-speed camera developed by O’Brien was used for the photographic record. A narrow slit illuminated by the Strobolux was imaged on a strip of 16-mm Super-XX film carried on the inner circumference of a drum mounted on the shaft of a vertical motor. When the drum was driven at 10 800 rpm, the exposure time on the film was 0.236 µsec. The film was calibrated by exposing a standard lamp through a stepped slit on the same record. The peak luminance through a 550-mµ interference filter is 7660 c/cm2 of tube area. The duration of the flash is about 100 µsec with 90% of the energy delivered in 41 µsec.
© 1959 Optical Society of AmericaFull Article | PDF Article