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DIY High Resolution Spectrometer (2018)

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Re: DIY High Resolution Spectrometer (2018)

#21

Post by jamal-kumar »

I've been wanting a cheap, no-cloud raman spectrometer in my pocket for a while now.

Like something that can plug into something as universal as an audio jack on a phone, reflecting the laser back into its built in camera. I know there was some options out there that were cloud-based but I want one simply lets us interpret the samples and their readings ourselves with lab device quality output.

DIY stuff like this is ultra cool but it's like miniaturize-able for sure, and something you can run with open source software.

I know it's around the corner, I've read about it. It's like the next killer feature for new cell phones already. [1] Making it open source so some corporations who are doing cloudy things with your spectrometer data is definitely an international research security imperative.

[1] https://aip.scitation.org/doi/10.1063/5.0046281

Re: DIY High Resolution Spectrometer (2018)

#22

Post by schobi »

PragmaticPulp wrote: post #9
paulkrush wrote: post #2

Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru...

> Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru... The linked project uses a 4000px wide image sensor and the second example in the a…

Not going to happen!

Photons of different wavelength are absorbed and converted at different depth in silicon sensors. Blue photons mostly convert at the surface, while red go much deeper into the sensor. The pixel electronics of a regular cmos image sensor however will only collect the resulting electrons in a certain region at the surface. If an electron is generated somewhere else, it will recombine and be 'lost', not contributing to the signal.

Depending on the sensor, at 1000nm only Why? Silicon has a band gap of 1.12eV - photons with lower energy will not interact. This corresponds to ~1100nm - you will need sensors with different materials

Re: DIY High Resolution Spectrometer (2018)

#23

Post by jacquesm »

PragmaticPulp wrote: post #9
paulkrush wrote: post #2

Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru...

> Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru... The linked project uses a 4000px wide image sensor and the second example in the a…

You'd better start saving for a cryo setup as well then, because even if your sensor has the right sensitivity at those wavelengths it will be hard to avoid contaminating the results if the gear itself is not chilled, unless the signal you are sampling is overwhelmingly stronger than the stray photons produced by the gear.

Re: DIY High Resolution Spectrometer (2018)

#24

Post by qwertox »

jfnetsec wrote: post #13

almost completely off topic but btw the o in spectrometer, speedometer, worldometer, whatever is called an interfix. you've heard of suffixes and prefixes, well interfixes unlike those two have no meaning other than to join two root words (as in words that can't be used as suffixes or prefixes).

You may be doubting if your comment was actually useful: thanks for posting it, for not discarding it.

Re: DIY High Resolution Spectrometer (2018)

#25

Post by Rnonymous »

paulkrush wrote: post #2

Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru...

As mentioned below, the main problem is the detector. Most detectors are Si CCD. meaning the Si is fundamentally limited to 1100nm due to bandgap. Going beyond that means you need a different material such as InGaAs or Ge, unfortunately CCDs are not as common or are expensive for these materials. Which then gives you two choices:

- an array detector, which is pricey.

- a single detector such as a photodiode behind a second slit. a detector such as these https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=12... With a moving(rotating) grating, so that the wavelengths can be reached by moving the grating.

The latter is quite common in lab spectrometers.

Re: DIY High Resolution Spectrometer (2018)

#29

Post by hoseja »

jamal-kumar wrote: post #21

I've been wanting a cheap, no-cloud raman spectrometer in my pocket for a while now. Like something that can plug into something as universal as an audio jack on a phone, reflecting the laser back into its built in camera. I know there was some options out there that were cloud-based but I want one simply lets us interpret the samples and their readings ourselves with lab device quality output. DIY stuff like this is…

I don't think smartphone manufacturers are incentivized to put better, cooler sensors into them; unless those sensors can be used to better spy on you, which I don't think a spectrometer can be.

Re: DIY High Resolution Spectrometer (2018)

#30

Post by paulkrush »

schobi wrote: post #22
PragmaticPulp wrote: post #9

Earlier quoted context omitted.

> Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru... The linked project uses a 4000px wide image sensor and the second example in the a…

Not going to happen! Photons of different wavelength are absorbed and converted at different depth in silicon sensors. Blue photons mostly convert at the surface, while red go much deeper into the sensor. The pixel electronics of a regular cmos image sensor however will only collect the resulting electrons in a certain region at the surface. If an electron is generated somewhere else, it will recombine and be 'lost',…

Thanks, this was very helpful(and interesting) for the IR part of the question.
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