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I recently got a spectrometer with a fibre input from fleabay, which I've been enjoying playing with. I got a tiny ruby stone and shone a tungsten halogen ligh
by anfractuosity 3y ago
I recently got a spectrometer with a fibre input from fleabay, which I've been enjoying playing with.
I got a tiny ruby stone and shone a tungsten halogen light behind it -
https://www.anfractuosity.com/files/ruby.png https://www.anfractuosity.com/files/ruby.png I could see a dip around 694nm like someone else's spectrum - https://en.wikipedia.org/wiki/Ruby_laser#/media/File:Ruby_transmittance.svg https://en.wikipedia.org/wiki/Ruby_laser#/media/File:Ruby_tr.... This is the same wavelength that ruby lasers emit light apparently.
I'm planning on using it to try to measure ABV of beer/spirits. I noticed some of the cuvette holders with fibre inputs seem to be crazy expensive though, so probably need to DIY that!
A while ago I got a little spectroscope that looked a bit like - https://shop.wf-education.com/science/op66595.html https://shop.wf-education.com/science/op66595.html. And simply attached to a camera, to generate graph from.
- HerculePoirot 3y agoA $500 DIY near-IR spectrometer that would sell for $10,000 https://caoyuan.scripts.mit.edu/ir_spec.html https://caoyuan.scripts.mit.edu/ir_spec.html
- anfractuosity 3y agoLooks very impressive!, thanks
- qwertox 3y agoCurrent discussion: https://news.ycombinator.com/item?id=37498142 https://news.ycombinator.com/item?id=37498142
- OJFord 3y agoWhat sort of wavelength of sensor do you need for ABV measurements? Size of ethanol particle? Half it because of Nyquist? Or what does it have to relate to? I'm just wondering how fancy vs. DIY you need for that sort of purpose basically.
- anfractuosity 3y agoThis is the paper I've been looking at - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356901/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356901/ they make use of a tungsten lamp and IR leds, I tried with just a tungsten lamp and only really saw a plateau around 900nm when ethanol was present. Their spectrometer goes further into IR than mine, mine tops out around 1000nm, but hopefully I'll still be able to get some results when I add IR LEDs. I'm not sure what the peaks correspond to regarding the ethanol molecule though afraid. It's been a while since I read the paper, but maybe that indicates this. I believe my spectrometer just has a linear CCD sensor.
- s0rce 3y agoFor ABV you'd usually use refractive index, there are low cost non-electronic refractometers, you can also use density. Alcohol doesn't absorb much light so generally not done by UV or IR.
- qwertox 3y agoFYI, the ruby.png image is 19200 x 14400 pixels big. Luckily it's mostly white.
- anfractuosity 3y agoThanks for the heads up, just regenerated the graph
- kurthr 3y agoHey, try heating up that ruby! It'll turn darker as the bandgap moves toward the IR. You can shift your dip with a hair drier. It should move from ~1.15eV at room temp 75F/25C to ~1.10eV at 120F/50C, which should be about 35nm longer.
- anfractuosity 3y agoOoh, cool! Will definitely have to give that a shot.
- kurthr 3y agoUse liquid nitrogen and you can get it to turn light pink!
- s0rce 3y agoAseq? I've had good luck with these for a few applications.