Philips HPI-TD 1000W/D

Here you can see a 1kW Philips HPI-TD 1000W/D lamp as it was designed for overhead projectors and episcopes as a replacement for tungsten incandescent lamps. It is unsual that this lamp is the bare arc tube. Osram of Germany offered similar lamps first under the SOLARCA brand and then plainly rebranded HQI-TS in 250, 400 and 1000W. The 1000W lamp was not interchangebl with this one, as it was longer and featured an external envelope.

This lamp is of more modern design featuring a gold heat reclective coating araound the electrode which is rather annoying. See wile it looks very Fance when new, after this lamp is lit for a bit of time, the gold will stop sticking to the glass and will be wiped off just by touching it. The same problem can be seen with Philips HPA series of lamp, which is the reason that lamps employing an oxide coating rather then the gold coating like Osram Ultramed lamps were superior.

Eventually these lamps wer phased out and replaced with more modern short arc Lamps like the Osram HMP series