Sciencemadness Discussion Board

test lamp needed

chemrox - 9-11-2008 at 18:53

I need a test lamp for callibrating my IR. I could use polystyrene and adjust by trial and error but the procedure using the test lamp seems a lot more straightforward. I don't have the manual here but I recall it was a 1024 nm source that was needed.

vulture - 10-11-2008 at 02:44

1024nm, isn't that a YAG laser?

chemrox - 10-11-2008 at 08:11

I'll check this am.

chemrox - 10-11-2008 at 18:50

It needs to be a monchromatic source not necessesarily coherent and it's one of the Hg vapor green lines... and it might have been 532 nm .. still have to look it up

watson.fawkes - 10-11-2008 at 21:43

If it's a mercury line, you can get that with an ordinary mercury vapor lamp, a diffraction grating, and a slit aperture. Use a cheap mercury lamp, one without phosphors, special filter glass, other vaporants, etc.; just the mercury, please. Put a slit in front of the lamp. Look at the slip through the diffraction grating to determine the angle.

You can pick out the line by eye if you're familiar with the spectrum. Here's a page with spectrum pictures taken from various lamps. The 546 nm line is green.

chief - 11-11-2008 at 15:09

Calibration on only 1 line ?? Usually one would distribute several lines over all the lambda-range of the spectrometer, and then derive some polynome for mapping the data or something like that.

What would give a good IR-Standard might be the question:
==> easily obtainable substance,
==> with relyingly reproducible spectrum

Then just take the spectrum, see what it appears to be and what it should be, and calibrate ...

watson.fawkes - 11-11-2008 at 15:48

Quote:
Originally posted by chief
Calibration on only 1 line ??
If you were building one from scratch, sure, one line would be greatly insufficient. But since chemrox said he needed a monochromatic source, that's what a single line is.

chemrox - 11-11-2008 at 19:01

the callibration with one line gets the grating angle in the ballpark and then the final tweaking is with indene if available or polystyrene