RLOD#15 (2020.05.21) 1963 Philips C011-01

The Philips model C011-01 is a special low-voltage incandescent lamp with a transverse coiled filament intended for the projection of a narrow light beam with a very precise pattern, useful in signaling applications of the kind found in lighthouses and aerodromes. Interestingly, the lamp features an aluminosilicate glass bulb designed to withstand a very high thermal load around the filament. The later is placed near the prefocus P40s end cap, leaving a large volume of gas above, needed for thermal dissipation and to prevent evaporated tungsten from condensing near the source of light. The filament operates above 3000 K to maximize output and luminance, resulting in a 23 lm/W efficacy at the cost of a mean service life limited to 500 h. Given its design, the C011-01 is intended for a vertical cap-down operation in luminaires equipped with a back mirror and filament-imaging optics in the front.