Question: Buggy spectral meter? Galaxy S7...

sirkubax asked on December 12, 2016 21:44
273 | 5 answers | shortlink


I've just build the tool from the kit that I've ordered.

  1. How to choose the rear camera on Galaxy S7 (Chrome browser)

  2. Why the image is so small, I did not find a way to enhance it, or it was unintuitive.

  3. The capture did start to work for a second, but then it did refuse to work anymore, probably I'd have to close the browser, I'll try later.

  4. Note - the tape or the box is conductive :/ my screen was constantly interrupted, I had to use small post it - so annoying - why did you even thought of using front camera.... ?

  5. I did try to point the spectrometer at the LED light, and the Ikea Vaxer light - so much noise on the screen... Why? Is the gap to wide (I did use sharp knife as gap-meter - suppose it is 0.3-0.5mm wide....)

Any thoughts? I'm kind of upset now - it supposed to work, but it seems like an alpha version... I know it is an open project, and I'd love it, but so many things failed to work in a row... It reminds me a linux 10 years ago - so buggy or intuitive...

How could I help you to debug this issue?

2016-12-12_22.32.56.jpg



spectrometer spectralworkbench red uvc save

question:general



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5 Answers

Hi! Thank you for helping debug, and for being an open source supporter! Seems to me like some instructions got lost in the wash, so i'll type them in here real quick:

(1.) On Android use the Firefox browser. Only this browser lets you choose the rear camera.

(4.) After solving #1, there will not be tape on your front screen!


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So you were right about 1 - on firefox rear camera works... thx Rear camera capture: 2016-12-12_23.07.11.png

p 6. How to get the image/spectrum to fill the whole capture field as on provided example? Is the project proper for a smartphone camera?

Ad. 5 Some picture showing the reflections while pointing on the lights

Led Red-Blue light 2016-12-12_23.10.53.png

Ikea Vaxer 2016-12-12_23.12.19.png


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Hi!
(5)You can try pointing your spectrometer to a white paper in the place of pointing it directly to the light.
(6) I think that depends on the resolution of your camera. If you use a camera with an picture output of 3500x2000 for example, the spectra will always be smaller that if your camera output is, lets say 900x600. Anyway the size of the image is not important for spectrometry unless you want to print the image.
Another thing you can do is what I do. Since spectralworkbench does not work on Iphone I capture my spectra using the regular camera (something you can do also offline) and then upload it to spectralworkbench. During this process you can crop the image.
You can also try reducing light inside the spectrometer https://publiclab.org/notes/xose/11-22-2016/reduce-light-inside-foldable-pl-spectrometer


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thx, I thought about using DSLR camera (EOS 350D) that has a bigger sensor and a better lens, it might (not sure yet) capture the spectrum better


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I've recently tried with a Nikon D700 + Elmarit 35mm with good results.
If you have an extra lens cap you can try making a hole and fix the spectrometer to it.
Also browsing the PL website just found this interesting post by @dhaffnersr about CFL calibration (Compact Fluorescent Light).
https://publiclab.org/notes/dhaffnersr/09-10-2016/a-near-perfect-cfl-compact-fluorescent-light-calibration


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