COBR-Polam Metal Halide LRJD 400W

This lamp is a prototype manufactured by COBR Polam - a small and semi-independent company which existed as the research and development laboratory of the Polish national lamp manufacturer, Polam. It appears to be substantially the same in construction as an earlier lamp that was manufactured by that company in the 1970s.

The lamp radiates a powerful light of unusually high colour temperature around 8000K, and a rather poor colour rendering index of about 60. Its chemistry is based on the Dysprosium iodide system as introduced by Osram during the 1970s. Whereas the Osram dysprosium lamps are also filled with thallium so as to raise the efficacy, and caesium to stabilise the arc by fattening its dimensions and making the lamp less susceptible to variations in burning position, this COBR-Polam lamp contains a much higher thallium component, and an additional dose of indium. Owing to the presence of indium's strong blue lines, it has an extremely high colour temperature light, while the thallium pushes the colour well above the blackbody locus. The application is not known, although since COBR-Polam is known to have produced many special discharge lamps for medical uses, it seems possible that it was developed for that application.

The arc tube design is similar to Osram's first dysprosium lamps of the 1970s. It has a 3-piece construction with conical end chambers, covered with a heat-reflective zirconia paint. Even the exhaust tip has been painted to prevent halide condensation. The arc tube is mounted in a high vacuum outer jacket to limit thermal losses, the vacuum being maintained by four barium getters and an annular strip of hydrogen getter material near the domed end.
Manufacturer: Centralny Osrodek Badawczo-Rozwojowy POLAM
Lamp Power: 370 Watts
Lamp Current: 115 Volts
Lamp Voltage: 3.5 Amperes
Cap Type: E40s/45 Nickel plated brass + porcelain
Bulb Type: T-46 TD-14½ in eighths/inch
Bulb Finish: Clear Borosilicate glass
Electrodes: Backwound Tungsten No emitter
Arc Length:
Atmosphere: Inner: Hg, (Dy,In,Tl)Ix | Ar Outer: Hard vacuum
Luminous Flux: 26,500 lumens
Luminous Efficacy: 71.5 lm/W
Colour Temperature & CRI: CCT: 8000K CRI: Ra60
Chromaticity Co-ordinates: CCx: 0.272 CCy: 0.387
Rated Lifetime: Approx. 10,000 hours
Warm-up & Re-strike Time: 3 minutes 10 minutes
Burning Position: Universal
Overall Length: 145 mm 53/4 inches
Light Centre Length:
Factory: Warsaw R&D Lab Poland
Date of Manufacture: 1st December 1997
Original / Present Value: No commercial value
References: 1) Private Communication, Bartlomiej Kuzma, 2014.
2) Manufacturing specifications Telam LRJD 400W lamp, on website of Polish Lighting Gallery.
3) Description of lamp on French Public Lighting Forum.