Question: Best light source for spectrometer?

jneish is asking a question about spectrometry: Subscribe to answer questions on this topic

jneish asked on July 10, 2018 18:25
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I am wondering what light source is best for the lego spectrometer - I remember an old writeup discussing halogen bulbs and fluorescing laser pointers. Are these still suggested?

We are hoping to use the spectrometer to measure the concentration of various petroleum hydrocarbons. Has anyone experimented with various light sources for similar studies and found one they like best? In the spirit of open source data, we would like to be able to compare spectrographs but differing light sources would make this less helpful...



2 Comments

A couple of gottchas here. I think you want to use the lego spectrometer with a light source. The light source would be fed through a cuvette filled with the liquid for analysis, correct? Final assumption- your measurements will be done in the visible.

If all of the above are true, then a tungsten halogen lamp is a good source. Usually, coverage is pretty good from say 350 nm to 700 nm. The intensity will vary, but if ratioed , it can be accounted for.

Good luck

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The spectrum of most common halogen lamps is neither smooth nor flat and generally do not have published spectral data. You might consider the Solux 4700K (only the 4700K) which has relatively broad, and smooth, spectrum and has published data. The following links might be helpful: https://publiclab.org/notes/stoft/03-02-2015/plab-3-spectrometer-upgrade-prototype https://publiclab.org/notes/stoft/03-06-2015/plab-3-gain-correction .

As for measuring petrochemicals, that is likely an extremely difficult task using only visible light. You might find the following links helpful. https://publiclab.org/notes/stoft/01-19-2016/otk-proto3 and https://publiclab.org/notes/stoft/01-26-2016/otk-proto3-analysis .


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