The Biplane Filament in Spotlighting

The high degree of uniformity and source of brightness that have made the biplane filament so desirable for motion picture projection prove to be valuable also in spotlighting. The two parallel rows of coils placed so that the coils of one plane fill the spaces between the coils of the other provide a light source of greater uniformity and double the average brightness of the monoplane filament construction. Results are given showing the increased uniformity of the spot and the higher intensities attained with biplane filament lamps as compared with monoplane filament lamps of the same rating. The three types of spotlights most commonly used—namely, the lens spotlight, the shallow paraboloid, and the stereopticon spotlight—have been subjected to test to determine their operating results.

Print ISSN

0097-5834

Published

1934-09

Content type

Original Research

DOI

10.5594/J05445