Osram Miniature UV Blacklight HNV 9W
During WW2 there was a heightened requirement for small sources of UV-A energy for operation on low voltage DC power supplies, for illumination of vehicle interiors - in particular for aircraft cockpits but also for train and truck dashboards. Until then it had been standard practice to employ miniature incandescent lamps, and this called for large numbers of lamps with complex illumination systems. It was also difficult to uniformly light large surfaces, with the result that some areas appeared brighter than others.

Parallel developments in fluorescent lighting at that time were resulting in new luminescent materials, and by painting these onto control panels the phosphors could be illuminated uniformly by floodlighting the area with invisible UV-A radiation. Another advantage of this approach was that the total light level was greatly reduced, making such vehicles less obvious to enemy aircraft.

One of Osram's first lamps for such applications was the HgN 13W, and by 1943 it had been joined by this even smaller and simpler HNV 9W. This lamp has no positive column discharge, and operates on the glow discharge principle. A tungsten filament is connected in parallel across a pair of electrodes, and following momentary preheating this generates sufficient free electrons for a small discharge to become established. This short-circuits the filament, which automatically extinguishes. The electrodes are asymmetric, the central anode having smaller dimensions than the adjacent off-centre cathode. The lamp is equipped with a bayonet cap as is customary for improved vibration resistance on vehicles, the pins being asymmetric so as to ensure correct polarity of the DC supply.
Manufacturer: Osram KG
Lamp Power: 9 Watts  
Lamp Voltage: 9-12 Volts  
Lamp Current: 0.7 Amperes  
Cap Type: B22d-3 Brass + Vitrite
Bulb Type: T-14 T-4½ in eighths/inch
Bulb Finish: Woods Glass UV-A transmitting
Electrodes: Tungsten Coils CC-2U filament
Electrode Gap: 5mm
Atmosphere: Hg | Ar
Luminous Flux: N/A
Luminous Efficacy: N/A
UV-A Irradiance: 1 mW/m² @ 1m distance
Colour Temperature & CRI: CCT: N/A CRI: N/A
Chromaticity Co-ordinates: CCx: 0.256 CCy:0.120
Rated Lifetime: Unknown
Warm-up & Re-strike Time: 1 minute Instantaneous
Burning Position: Universal
Overall Length: 56 mm 21/4 inches
Factory: Werk-S Charlottenburg Berlin, Germany
Date of Manufacture: 1943 October Date Code: z13
Original Value: Unknown
References: 1) Eine Lampe zur Fluoreszenzanregung für Sonderzwecke, E.Summerer, Technisch-Wissenschaftliche Abhandlungen der Osram-Gesellschaft, 1943 p66.