OpenRAMAN – Low-cost, high-performance, open-source Raman spectrometer
open-raman.org
open-raman.org
I mention this because it seems counter to what calling something "open source" means to most people. On the main page of the project, they say "It is strictly reserved for non-commercial applications" which... IANAL but I think the license limits commercial use of the design, but not of the device created with the design? Also NoDerivatives runs pretty counter the open source ethos IMO.
This project is not open. A non commercial license is in direct conflict with what is the commonly accepted definition of "open" (source or hardware) [1].
Normally when hardware projects claim to be "open source", I give them a pass as they sometimes have the code or other firmware under a GPL-compatible license even when they have the hardware files under a proprietary or non-commercial license. This content is not providing any source or other files under an open/free/libre license.
This project is "open washing" and should not be considered an "open source" project.
[1] https://en.wikipedia.org/wiki/Open-source_license
> " ... Licenses which only permit non-commercial redistribution or modification of the source code for personal use only are generally not considered as open-source licenses. ... "
Looking through the BOM, I feel there's a good bit of fat to be trimmed actually. They splash €85 on a linear regulated power supply (you can get something similar giving clean power for $20 in bulk), and the camera setup (sensor, lens, related hardware) costs more than €600 in total. While there's a good reason they picked the lens they did [0] I feel the sensor (might) be replaceable by a new Raspberry Pi setup (also C-mount) - that'd save $400!
Then there's a lot of money (couple hundred) in fancy plastic/aluminum parts. Manufacturing in higher quantities could save quite a lot there.
There's some stuff that is much trickier to push down in price much: laser stuff/dichroic mirrors, filters, etc are tough.
Still, though, I feel that this has potential to eventually come down a good bit in price, and I really look forward to seeing that eventually happen!
[0] http://www.thepulsar.be/article/raman-imaging-lens-upgrade/
Caveat: this is much lower quality, but for a "home" kit, this is probably better. The OpenRAMAN edition is much higher quality and aimed lowering the bar to entry and making lab setups cheaper (Raman Spectroscopy can actually be useful in a lot of settings).
It seems very well developed. The open source RamanPI [1] got some traction here a while ago. This looks like it may be more costly than RamanPI but it also is more thoroughly developed.
On the other hand, Luc's results are drop-dead awesome: http://www.thepulsar.be/article/some-diy-raman-spectra/
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My money would be on mass spec, although it requires high voltage and vacuum. Back in my old university days Zbigniew Gasnaya made a home gamer mass spec that worked fine for what looked to be about 300$ in today's parts
3 high DC voltage plates, a harbor freight vacuum, an amp...
As with his Raman setup, there were some good questions raised in the comments about whether he really saw the effect in question or just got lucky with plausible-appearing artifacts. It's hard to assess validity from the presented results alone, which is unfortunately common in Ben's videos. In the Raman video, he didn't test anything but a single styrofoam cup, and in the mass-spec video he didn't do the obvious baseline run with a clean filament.
Ben's channel is one of those rare ones where the comments are worth reading. You can really see how easy it is for a scientist to inadvertently fool themselves and others. I often end up yelling at the screen, but it's still my favorite YouTube channel of all time.
I think Ben's misused over there at google. He should be designing the national high school science lab curriculum.
http://www.open-raman.org/quantifying-methanol-in-ethanol-us...
It can be used to detect and quantify methanol in ethanol. This is interesting because ethanol is (relatively) safe to drink, while methanol is metabolized to poisonous compounds when ingested. Methanol and ethanol look the same and have nearly identical densities. The odor and taste of methanol are distinguishable from ethanol only at high concentrations. Raman spectroscopy is one way to distinguish a dangerously adulterated alcoholic beverage from a safe one.
You do need to put a sample of the substance to be tested in the machine, though. You can't point the machine at a container in front of you and get a reading. Also, Raman spectroscopy is suitable for distinguishing many but not all substances. The Tricorder's capabilities for universal remote analysis are superior if fictional.
Here is a paper detailing its use in determining methanol content of ethanol spirits: https://pubs.rsc.org/en/content/articlelanding/2019/an/c8an0...
The methanol I've worked with has a strong wintergreen odor, impossible to mistake for ethanol. I'd always assumed that's just what methanol smells like. Is it actually an odorant?
The only consumer product I know that resembles this is the SCiO: https://www.consumerphysics.com/scio-for-consumers/
Not everything is so constrained. Lasers can get smaller. Certainly electronics. As those things get more efficient, the batteries can get smaller.
Now, it all depends on what you're trying to measure. And there are cases where the chemicals themselves cooperate with you in some way. For this reason, single purpose instruments can often be quite small. An example is the finger cuff for blood oxygen.
If you search for mini- or micro-spectrometer, you'll find that these things are all over the place. Many of them demonstrate one interesting application with great fanfare, that is perpetually almost sensitive enough for practical use.
It seems quite simple, in that it seems to use a light source and looks at the reflection using photodiodes with different lenses on top.
So as I understand it wouldn't perform as well as a spectrometer with diffraction grating and linear CCD, but would be interested to hear from someone knowledgeable about spectrometers about that.
But it does seem to use a simpler principle than a raman spectrometer, I believe this is the general term for the approach it uses - https://en.wikipedia.org/wiki/Near-infrared_spectroscopy