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Thread: Looking for an economical calibration light source at ~ 400nm

  1. #11
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    Quote Originally Posted by DZ View Post
    That's what I thought. I had run a test on a couple blueray diodes for dave at LPF a year or two ago and used 532nm and 473nm as the stage to determine the blueray diodes wavelength, knowing that 532 and 473 should be dead on. If I remember correctly, I had one as short as 402nm and one as long as 416nm.
    Ya, that makes sense. You would expect 405s to vary just as much as 445s. And given that my purpose for calibrating in this range is to gain the ability to test 405nm diodes, it would be conceptually inappropriate to use a 405 as a calibration source anyway

    Quote Originally Posted by -bart- View Post
    I recall that your average nightclub blacklight fluorescent-tube has a ~370 nm peak.
    It won't get cheaper than that.
    Not sure about the spectral bandwidth, pretty broad, probably like 20nm.
    I thought about that - but as mentioned the bandwidth is poor, from 20 to 50nm.

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    Quote Originally Posted by mixedgas View Post
    I can do the glassware and pump a pure argon lamp for you if you need it. So can any neon sign shop.

    GE AR2s show up on Epay from time to time for about 20$.
    Steve
    Excuse my double-post. I think I have some post/refresh lag. Re the GE bulbs, this wouldn't work would it? (on account of being AR1)
    http://www.ebay.com/itm/GE-W1A-AR-1-...ht_2463wt_1396

    The Penray lamp approach looks promising. It seems like Mercury, Krypton, or Argon would be the most ideal for my purposes. Reading the line "UVP invented the Pen-RayŽ Lamp and can provide the most experience, history and knowledge in the industry" immediately signals "pricey" in my mind though - am I wrong?

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    The whole GE AR series works off 110 in standard sockets and needs no external ballast resistor.
    Go for it.

    Steve

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    The Penray lamp approach looks promising. It seems like Mercury, Krypton, or Argon would be the most ideal for my purposes. Reading the line "UVP invented the Pen-RayŽ Lamp and can provide the most experience, history and knowledge in the industry" immediately signals "pricey" in my mind though - am I wrong?[/QUOTE]

    You betcha, they get serious money for those.

    I think I have two penray HGs I picked up at a Hamfest, without the transformers.

    Let me go check, I'll post again this evening.

    Steve

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    Quote Originally Posted by mixedgas View Post
    You betcha, they get serious money for those. I think I have two penray HGs I picked up at a Hamfest, without the transformers.

    Let me go check, I'll post again this evening.
    Thanks! My bet is that you'd probably want to sell them for a bit more than I'd have to spend on this project, but I'm still interested to see what you come up with.

    Re: the AR bulbs - I think I'd still run into the problem of basically have strong lines in the 350s, which is too low.

    It sounds like what I probably need is a low-pressure mercury lamp. There's a REALLY strong line at 398, which would be perfect.

  6. #16
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    Price is right...

    http://www.ebay.com/itm/GE-W1A-AR-1-...ht_2463wt_1396


    I may have to cal a spectrometer next week. This just got interesting on a personal bias.

    SO:

    http://web.mit.edu/8.13/8.13d/manual...tion-lamps.pdf

    Nice argon lines listed there at 394 and 404. Probably weak, but you'd need to look at the NBS (now NIST) online spectral book to be sure.


    Re the PenRays...

    Um, 10$ + shipping is going to be too much?

    Steve
    Last edited by mixedgas; 01-25-2012 at 08:44.

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    Quote Originally Posted by mixedgas View Post
    Before we go too far down the Argon route, can I ask for clarification on a few points?

    1) Am I correct that Argon would give me a strong spectral line at 357/358 and then another strong line at 440 (My source btw is: http://physics.nist.gov/PhysRefData/ASD/lines_form.html)

    2) That bulb says AR-1. The lines at 357/358, and 440 are AR-II. Does that imply that the AR-1 bulb won't have those lines? Or is this an incorrect interpretation?

    3) 357/358 would be below my calibration range, but 440 wouldn't. If I calibrated a spectrometer using 4 coefficients (4 spectral lines), those being 440, 473, 532, and 561, would it be inappropriate to use this spectrometer to subsequently measure 405nm diodes? (since I wouldn't have had a calibrating spectral line near to the 405nm wavelength)

    EDIT:
    The Argon lines at 394 and 404 are REALLY weak. The realtive intensity of the 394nm and 404nm Argon lines are 204 and 288. I'm not sure what that is relative to, but for comparison, the Argon ilnes at 357nm and 358nm have a relative intensity of 12,000+ and the 440nm line is 8,000.

    So I don't think an Argon source would be usable for the 394/404 line as calibration. Hg on the other hand, has a VERY strong line at 398nm - a relative intensity of 10,000,000 which appears to be it's strongest line in the 350 to 450nm range.

    $10 would be no problem at all Is it Mercury?
    Last edited by rhd; 01-25-2012 at 09:09.

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    Too bad they can't make a xenon or mercury-neon laser. There's some fun frequencies in there

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    Quote Originally Posted by steve-o View Post
    Too bad they can't make a xenon or mercury-neon laser. There's some fun frequencies in there
    Or a low pressure sodium vapor laser, with corresponding efficacy, that would be the day !

  10. #20
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    Quote Originally Posted by -bart- View Post
    Or a low pressure sodium vapor laser, with corresponding efficacy, that would be the day !
    Xenon lases, neon-mercury mixes lase. They just lase pulsed. I've never gotten my hands on a pulsed xenon, they were made for resistor trimmers. I've seen them, but always get outbid.

    Mercury lasing was what Bridges was doing when he found Argon lases.

    AR1 is simply the part number of the lamp, it is not a ion spectrum, just a glow spectrum. GE drives argon quite hard in the lamp. Can't you just lengthen your CCDs integration time and pick up the weak lines?

    IF not the AR1 lamp, why do I just not carefully pack up a penray and loan it to you.
    Steve

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