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

  1. #31
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    Xytrell: Thank you

    There's a line that's showing up at 626.64950, which is what I'm going to use - I can see that line clearly in your output.

  2. #32
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    Be careful on the flourescent lamp cal, some of the new lamps use a neon-krypton mix and almost no mercury.

    Steve

  3. #33
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    Quote Originally Posted by mixedgas View Post
    Be careful on the flourescent lamp cal, some of the new lamps use a neon-krypton mix and almost no mercury.

    Steve

    Interesting. Well, there WAS a line in this particular bulb around 435.8. I assumed this was the G-line from mercury. If indeed this was a neon krypton mix, then there's nothing strong (it seems) in neon around that range. What there IS, is a krypton line at 435.5. That's pretty close - close enough that I'm not feeling bad about the calibration.

    Any way to verify what a CFL would be filled with?

  4. #34
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    Any way to verify what a CFL would be filled with?[/QUOTE]

    A USB spectrometer?

    Seriously, there should be a transparent part of the bulb in the base some where. Cathodes in the mixed fill lamps will have a orange glow of neon recombination lines around one of the electrodes.

    Mercury will usually emit its green and UV lines when the cathode is heated before the lamp arc starts. The Krypton will NOT glow with just a hot cathode. 12V of voltage drop across the hot cathode is enough to ionize the mercury but not the krypton. This was used to make UV lights for aircraft cockpits in World War II, just take a 24V bulb and add pure mercury to the lamp before sealing.

    Steve
    Last edited by mixedgas; 02-08-2012 at 10:17.

  5. #35
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    Even in the low-mercury lamps, mercury is still the primary way to excite the phosphors, isn't it?

  6. #36
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    Quote Originally Posted by Xytrell View Post
    Even in the low-mercury lamps, mercury is still the primary way to excite the phosphors, isn't it?
    For the CFL, I'd located a fairly old bulb that I'm certain has a Mercury fill. Even if it didn't, it would still be a Krypton line at 0.3nm from the Mercury G Line, so the impact on calibration would be negligible. I think I found a final calibration setup, and I'd happily receive any critique of it that anyone might want to contribute:

    435.8 - Mercury G Line (from a CFL)
    473.? - DPSS
    532.? - DPSS
    589.? - DPSS
    632.8 - HeNe

    I need to locate the precise DPSS wavelengths, but I'll do that before undertaking my final calibration. I think I have them written somewhere. From memory, 473 isn't exactly 473.0.

  7. #37
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    Spectrum studio CSV file modification


    Hello to everyone, this is my very first post on this forum.

    I just want to share my modification of Science Surplus Spectrometer. Instead of calibration of squeezing the spectrum into wavelenght range, my approch was, Calibrate the spectrum adjusting the bottom pixel numbers as wavelenght. Basically in the graph normally you see wavelenght from 0 to 2048. I have modified the CSV. file to show from 383nm - 642nm. I have created a exel file to modify this range, and using Osram and Neon i have calibrated this table. For thouse who find this solution helpfull i can share and explain how it is possible. My another modification was to make this spectrometer possible to use internal and external CCD Linear Sensor IC SONY CDIP-22 ILX511 but that will be another post.. Click image for larger version. 

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