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For whatever reason, the "blinded by the light" contest has stuck in my head, motivating me to take some images of sources.
As usual, don't try this at home.
Halogen (incandescent) bulbs are fairly easy to photograph: this is a standard 12V 100W bulb
[PLAIN]http://img713.imageshack.us/img713/1043/hibeams.jpg
This was done by adding together an image of the unlit bulb with an image of the lit bulb- that's why the reflected filament is cold metal. Easy breezy.
More interesting are arc lamps- I have a spare 100W Hg high-pressure arc, so I thought it would be interesting to get some images while it was firing. Here's the unlit bulb-
[PLAIN]http://img141.imageshack.us/img141/3287/unlit.jpg
The gap is about 1 mm, and somewhere inside is about 100 ug of Hg. There's other gases as well. After taking this image, I stopped down the lens to about f/120, set my shutter speed to 1/640 s, turned on the bulb and started snapping away, decreasing the shutter speed all the way down to 1/8000 s as the bulb came on- the process took about 20 seconds. After it was lit for a few minutes, I increased the shutter back to 1/60s and turned off the bulb to take an image of the hot electrodes.
I've never seen images of this process. Arc lamps are fairly complex to understand, but it appears that there is a multicolored diffuse glow from the other gases present, which heats up the Hg. The diffuse glow then goes away, and as the Hg heats up, it pools and collects in the glass as it evaporates, finally resulting in a concentrated arc.
The cooldown image clearly shows the thermal expansion of the electrodes.
[PLAIN]http://img197.imageshack.us/img197/8607/startup1.jpg
[PLAIN]http://img141.imageshack.us/img141/9681/startup2.jpg
[PLAIN]http://img441.imageshack.us/img441/4006/startup5.jpg
[PLAIN]http://img715.imageshack.us/img715/8358/startup8.jpg
[PLAIN]http://img251.imageshack.us/img251/4813/lits.jpg
[PLAIN]http://img703.imageshack.us/img703/6186/cooldown.jpg
The other sources I want to try next are a HeNe laser (which I have to disassemble first) and a 1200W medium-pressure Hg arc we use for lithography. The laser should be straightforward, but the MP arc may be problematic due to the excessive amount of UV light. Stay tuned...
As usual, don't try this at home.
Halogen (incandescent) bulbs are fairly easy to photograph: this is a standard 12V 100W bulb
[PLAIN]http://img713.imageshack.us/img713/1043/hibeams.jpg
This was done by adding together an image of the unlit bulb with an image of the lit bulb- that's why the reflected filament is cold metal. Easy breezy.
More interesting are arc lamps- I have a spare 100W Hg high-pressure arc, so I thought it would be interesting to get some images while it was firing. Here's the unlit bulb-
[PLAIN]http://img141.imageshack.us/img141/3287/unlit.jpg
The gap is about 1 mm, and somewhere inside is about 100 ug of Hg. There's other gases as well. After taking this image, I stopped down the lens to about f/120, set my shutter speed to 1/640 s, turned on the bulb and started snapping away, decreasing the shutter speed all the way down to 1/8000 s as the bulb came on- the process took about 20 seconds. After it was lit for a few minutes, I increased the shutter back to 1/60s and turned off the bulb to take an image of the hot electrodes.
I've never seen images of this process. Arc lamps are fairly complex to understand, but it appears that there is a multicolored diffuse glow from the other gases present, which heats up the Hg. The diffuse glow then goes away, and as the Hg heats up, it pools and collects in the glass as it evaporates, finally resulting in a concentrated arc.
The cooldown image clearly shows the thermal expansion of the electrodes.
[PLAIN]http://img197.imageshack.us/img197/8607/startup1.jpg
[PLAIN]http://img141.imageshack.us/img141/9681/startup2.jpg
[PLAIN]http://img441.imageshack.us/img441/4006/startup5.jpg
[PLAIN]http://img715.imageshack.us/img715/8358/startup8.jpg
[PLAIN]http://img251.imageshack.us/img251/4813/lits.jpg
[PLAIN]http://img703.imageshack.us/img703/6186/cooldown.jpg
The other sources I want to try next are a HeNe laser (which I have to disassemble first) and a 1200W medium-pressure Hg arc we use for lithography. The laser should be straightforward, but the MP arc may be problematic due to the excessive amount of UV light. Stay tuned...
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