Film-Tech Forum ARCHIVE: Looking for IR spectrum data for different makes of bulbs.

This is topic Looking for IR spectrum data for different makes of bulbs. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Eric Robinson (Member # 2966) on 07-02-2007, 01:45 PM:

I'm interested in comparing infrared spectrum output from different makes of bulbs. Anyone know if this data is readily available?

Posted by Michael Moore (Member # 3867) on 07-02-2007, 02:08 PM:

I've asked this question before and all I got from people here is nothing, I can measure it because I have an avaspec 211c with fiber optics. I have not done so because I only have one bulb and none for comparisons. I can do it if you want but it is going to take me till next month because I have my lamp house down. I have an ASL bulb and that is it. What wave lengths are you interested in?

if you check out http://en.wikipedia.org/wiki/Xenon_arc_lamp

there is a discussion about the IR spectrum I believe in the 800-950 range.

I never looked into the manufactures of the bulbs but I'm sure they have the data.

Mike

Posted by John Hawkinson (Member # 1135) on 07-02-2007, 04:33 PM:

Why is this data interesting?

Osram's Technology and Applications guide has a graph on p.12 for "a typical XBO lamp" versus a black-body radiator. (For some reason the graph doesn't show up in the copy in the Manuals section on Film-Tech...)

--jhawk

[ 07-04-2007, 11:12 AM: Message edited by: John Hawkinson ]

Posted by Eric Robinson (Member # 2966) on 07-02-2007, 06:10 PM:

Having data about the IR spectrum would help me understand which bulbs generate more heat or less heat. Ideally I would like to buy a bulb which provides a lot of usable light and the smallest possible amount of IR.

Posted by John Pytlak (Member # 331) on 07-04-2007, 09:30 AM:

Frankly, I suspect that lamps of a given power produce very similar levels of Infrared energy. A Xenon arc's spectral output is relatively constant, and unless some sort of proprietary filter were used, I doubt lamps would be much different from each other.

Posted by Eric Robinson (Member # 2966) on 07-07-2007, 01:02 AM:

Thanks John, that's the kind of information I was looking for.

A 4500 watt Perkin Elmer bulb was installed in a super highlight II which had previously been using a Christie 4000 watt. The theatre ran the show and burnt each frame to a crisp.

When I interveined, I installed a heat filter lens in the snood. I adjusted the bulb amperage to 80% of max amperage, even still the film was very hot coming out of the film gate. I ended up defocusing the bulb for a darker picture and cooler film.

I was suspecting that this Perkin Elmer bulb somehow generated more heat than the Christie, so I thought I would try and analyze the IR spectrums to compare heat output to see if my suspicion was true or false.

Posted by Gordon McLeod (Member # 33) on 07-07-2007, 08:45 AM:

I beleive there is a fair bit of difference in the IR area between manufacturers
I have notice that with identical light distribution the PE/ASL lamps produce a measurable hotter projector head (same light level and distribution same cooling )
I would suspect it is in the doping of the electrodes or the type of quartz used?

Posted by Steve Guttag (Member # 268) on 07-07-2007, 09:05 AM:

Hmmmm...I've never noticed this before but I had never been looking either. You might try asking the people at ASL...they are some of the nicest people to talk to and they genuinely seem interested in making the lamps as good as possible.

Steve

Posted by John Pytlak (Member # 331) on 07-07-2007, 07:24 PM:

The total mass of the anode and cathode electrodes could have a small effect on the amount of IR (they get red hot), but the energy from the xenon plasma (arc) would predominate the output spectrum.

Posted by Steve Guttag (Member # 268) on 07-07-2007, 10:19 PM:

I have found that different lamp designs produce more/less light in different reflector/lens combinations. It isn't all about wattage. Some lamps work better with some reflectors than others.