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FrozenGate by Avery

470nm diode

Bluefan said:
Gas lasers can have very narrow linewidths too, a simple HeNe would extend your stable wavelength range to 632.8. A mixed gas laser would get you even wider. A simple gas discharge lamp doesn't have to be that expensive, take a look here:
Gas-discharge lamp - Wikipedia, the free encyclopedia
Neon lamps are quite common and some nice visible lines. Xenon looks perfect with lots of lines and are common as car headlights. All the lines are documented somewhere, so that won't be the problem.

If you think the math is a problem just post your measurement results here, I'll do a curve fit for you.
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Good point. I may see if I can take the Xenon approach. Here's a set of used Xenon bulbs that also includes the bulb holder and a more than adequate power supply unit. It has a buy-it-now of almost $19, but with the bidding at just a bit above $10 now, I think I could get it for a solid fifteen K ;)
eBay Motors - Xenon Headlights with SUPRCHARGD 2005-JAGUAR-S-TYPE

In all seriousness though, I have neither a car, nor xenon bulbs on hand. Would it really be as simple as buying $3 dollar xenon bulbs (like these) and giving them their stated 12V and ~8A (90W / 12V) ?

EDIT:
What about Krypton? It looks like the spectra is a little less crowded, and it might be easier to pull out particular lines. Plus, the bulbs are cheap, and seem to run on a low enough power that I could easily fire them up from my bench psu:
http://www.ebay.com/itm/Eveready-Kr...Flashlights&hash=item53e4f76fa1#ht_500wt_1180

Krypton
Krypton_Spectrum.jpg
 
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rhd said:
You could never get even a roughly decent calibration using diode lasers. You'd end up with a spectrometer many times less reliable than the diffraction grating approach.

"445"s would be completely out of the question, as they can range from 435 to 460.

As would "635"s, since even when not over-driven, they can very easily stray by 10nm or more.

"658"s are just as bad as 635s, even though their wavelength shifting gets less attention.

What's left? I suppose I don't know how stable 405s are, but I'd have to assume they vary a lot too, since they're the same bsic technology as 445s.

Long story short, you can't calibrate those machines using diode lasers as any part of the equation. DPSS should be doable.
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that was my point heh

a ML argon would do the trick i assume gas lasers are basically right on point... aren't they?
 
bennett326 said:
that was my point heh

a ML argon would do the trick i assume gas lasers are basically right on point... aren't they?
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No, that would be horrible since it covers such a narrow range of blue/green. You want your calibration to span as much of the spectrum that you plan to test in the future as possible.
 
rhd said:
No, that would be horrible since it covers such a narrow range of blue/green. You want your calibration to span as much of the spectrum that you plan to test in the future as possible.
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:yabbem: heh that makes sense
 
Those are just regular incandescent flashlight bulbs, rhd. Krypton is just the fill gas. Krypton is a better fill gas because it insulates the filament better than nitrogen. The fill gas emits no light of its own.

Any fluorescent lights will have the five main mercury lines that are easy to pick out

And I'm sure you'll have a power strip or other device with a lighted rocker switch that has a neon indicator inside:

neon_lamp_round_rocker_switch_YW1_217.jpg
org_shwtLJVCwiDH.jpg
 
I thought flourescent lights worked by using basically a phosphorescent coating inside the tubes that itself gave off the white light when excited by the UV emissions from the gas? Wouldn't that white light be made up of inconsistent (depending on coating) wavelengths?
 
rhd said:
I thought flourescent lights worked by using basically a phosphorescent coating inside the tubes that itself gave off the white light when excited by the UV emissions from the gas? Wouldn't that white light be made up of inconsistent (depending on coating) wavelengths?
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Those, too. But mercury is what generates the UV. Mercury also generates several visible lines that stand out as "spikes" among the rounded "hills" that the phosphors generates.

edit: Yeah, what Trevor said.
 
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I think I'll just use 5 dpss lasers.

What I loose, is a calibrating wavelength under 473. I cant imagine that this will have a fatal impact on my measurement of ~445 range lasers, especially not given that I'll be using five calibration lines instead of just four.

Edit, although it might stink for 630+ reds.....

If I use a florescent bulb, can it be any old cfl ?
 
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The spectral lines of a gas discharge lamp are very narrow and usable, fluorescent light aren't usable, the fluorescence is broadband. The ebay "HID" lamps are just incandescent lamps.
Neon indicators are gas discharge lamps, a HeNe laser would work fine too for calibration although that's a single line.
 
Just a tip... Try talking to your local university... I'm sure they would have a spectrometer you could calibrate against. They would also have a calibrating laser or light source for you to use.

Worth a shot...
 
Good idea. I'll pop the physics society an email later this week. I might even just stop by the Atmospheric Science building.
 
Let me ask the more practical (for me) question -

What are the downsides to shining a 473, 532, 556, 589, 594 at a blank surface, in a dark room, and using the resulting light to calibrate my equipment?
 
Total thread jack guys. :twak:

Can't you guys discuss your spectrometer calibration process in a.. spectrometer calibration thread?

(btw laser still hasn't arrived. It might not show up until tomorrow.)
 
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Cyparagon said:
Mercury lines are easily distinguished from the fluorescence bands. Haven't you read the thread?
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I must've missed that one, sorry. I haven't pointed a spectrometer at one so I thought a fluorescent lamp was mainly fluorescent.
rhd said:
Let me ask the more practical (for me) question -

What are the downsides to shining a 473, 532, 556, 589, 594 at a blank surface, in a dark room, and using the resulting light to calibrate my equipment?
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There's a chance the calibration is slightly less accurate at wavelengths far away from either end of your lasers' wavelength range, but if you look up the precise wavelengths of the lasers you should come a long way.
 
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