Optical Building a Raman spectrometer….

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Arduino technology has advanced to a point where it could potentially serve as a more practical alternative for on-the-spot drug purity testing compared to previous Raspberry Pi mass spectrometry projects, which were cumbersome and not mobile. The goal is to create a compact device that can recognize various drugs and their purity, with a focus on saving lives. There is a discussion about the differences between Raman and mass spectroscopy, clarifying that they are distinct techniques requiring different hardware. The conversation also highlights the importance of building a reliable database of real drugs for accurate identification. Overall, the community is exploring the feasibility of using Arduino sensors for this purpose.
  • #31
sbrothy said:
Your wife has no comments on that? :woot:
She mainly knows about the fire at home (at our old apartment years ago), and we laugh about it now. It involved a HAM radio project (we are both HAMs), where I made a fundamental mistake in building a large battery backup box. That was embarrassing...
 
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  • #32
berkeman said:
She mainly knows about the fire at home (at our old apartment years ago), and we laugh about it now. It involved a HAM radio project (we are both HAMs), where I made a fundamental mistake in building a large battery backup box. That was embarrassing...
Eeesh! :smile:
 
  • #33
The original paper (including the "Supporting Information") is a little silent on the nature of the lenses. I'd like to analyze my beam using a laser beam profiler but that darn thing is even more expensive than the spectrometer itself. I could build it myself but where will I end up having to build gizmo after gizmo?

I hope I understand that the long pass filter is supposed to filter out the Rayleigh radiation and as such is a pretty straightforward acqusition. The lenses om the other hand....

I've come to understand that I need biconvex lenses as the beam has to go back and forth through it. but their exact nature still eludes me a little. Can I just "try" with what I think are the proper ones, or do I need to profile the beam and "math it out"? The example I'm trying to follow uses a cube beam splitter (splitting the beam 70%/30%) but I'm wondering whether it wouldn't be smarter using a "proper" beam splitter?

Incidentally, I found this, related, document:

The Design and Construction of an Affordable Raman Spectrometer.
 
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  • #34
Well, actually doing my homework myself and understanding the difference between "cut-off" and "cut-on" filters I realize I need a "cut-off" filter blocking wavelengths longer than 550nm in order to cut off Rayleigh scattering radiation.

I'm surprised about the prices of these lenses though! Cheap they aren't! I read somewhere one can use ordinary magnifying glasses instead of biconvex lenses, but I doubt that works for laser light though.
 
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  • #35
  • #37
sbrothy said:
OK, after using my own brain and search skills I think I found the correct long-pass filter (no affiliation of course):

https://www.thorlabs.com/thorProduct.cfm?partNumber=FGL550S

Although I think I need an uncolored one.

and the lenses:

https://www.thorlabs.com/search/thorsearch.cfm?search=biconvex+lens+laser

Just need to find out which coating I need, if any.

I must admit I'm surprised that the filter and lenses are the most expensive part of this project!

Well, it turns out I “need” the colored one after all. At least that’s what they use in the paper I’m using as a guide.

Again, I’m in no way affiliated with Thorlabs. They just seem to have most of what I need, albeit, as I mentioned, they have no scruples charging you. In fact, they also have a complete Raman Spectrometer Kit.

Again, cheap it is not.
 
  • #38
I bought this SparkFun Triad Spectroscopy Sensor - AS7265x (Qwiic) but I think this was a mistake. It can do 3 different types of spectroscopy, but none of them is really what I need. It may turn out to be useful anyway though.

Details here:

https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/697/SEN-15050_Web.pdf

EDIT: Fun fact: as dimensions are difficult to assess I thought it was 10x10 cm, but it turned out to be 2x2 cm!

82829E37-3A3D-474E-8139-B9E1BA785CD9.webp
 
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  • #39
I bragged about not going down on equipment and then I stumbled across this guy’s blog.

I must admit I feel like I’m missing something here now.

Also, just ftr I should mention that my engineer partner bought the triad board (on my wrong request). I better find something constructive to use it for now! :smile: