Public Lab Research note

Reproducibility test using a CFL lamp

by viechdokter | April 13, 2016 14:26 13 Apr 14:26 | #12966 | #12966

Another test whether the PLab spectrometer 3.0 can achieve reproducible data curves.

This time I took a CFL (because of the nice narrow light bands in the spectrum) and put it 2 meters away from the spectrometer to avoid over-exposure. Dark room (not what you think!) with no stray light. Spectra taken between 12:54 pm and 14:58 pm, roughly in 10 minute intervals. I put the curves together in a gif animation that you can see here:


As you will notice, there are intensity differences between the captures but the main peak wavelengths are pretty stable. Best seen at the red curve peak to the right.

All 10 pictures are calibrated using the same curve. If you want to check the CSVs the spectra are saved under the names "Reproducibility test CFL #" (1 to 10).

The lamp was a "Corso CTU 20W" with a very bright but annoyingly flickering light.

PS: if you can't see the gif animation try IrfanView.


Hi, I cant seem to get the gif to play... what about adding all your spectra to a set and embedding here? Thanks! Eager to see these results.

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Here is a wmv file, it's not so well lined up like the gif but you can see what I mean by stable wavelengths.


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And here is the set. (Sorry I didn't know there was such a possibility. Loads of things I have to learn yet.) Oh, one proposal to the programmers: would be cool if I could check boxes to compare more than one image at a time in order to build a set quicker.

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Hey my friend! You can compare more than one image, if you look down a little on the page where you would calibrate your spectrum there is a button you can click that say "compare," when you click it it will let you compare as many spectra as you like.

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I already did compare all 10 spectra in the set but I always had to add a single spectrum at a time to get them all compared. What I meant were checkboxes where you can choose more than two spectra IN ONE GO. Lets check maybe 10 checkboxes at once and compare them.

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Oh super -- looks pretty good, really! And I appreciate that it's laborious to add each individually, and I hope that we can get more folks contributing to the code to add such features and make it easier and more powerful.

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