This may well be sufficient for most DIYBio applications.
It has low resolution (5 to 10 nm) so applications that need sub-nanometer resolution are out of the question (doppler astronomy, etc.).
The low resolution masks focus problems (different wavelengths focus at different distances, so one usually tilts the camera with respect to the grating, while this design has the image plane parallel to the grating).
It could easily be made self-calibrating by imaging mercury vapor lines in the top half of the image, and the sample in the bottom half, and adding a little software.
Since it is video, there is no way to let the sensor integrate a faint image over several seconds as there is when using a still camera, so the brightness of the sample could become a problem. Longer exposures are often useful when doing long range spectroscopy (to identify pollutants in smokestacks, e.g.).
Quite a nice project for $15.
On Mon, Feb 4, 2013 at 12:52 PM, Mac Cowell <mac@diybio.org> wrote:
Ah ha, calibration instructions! http://publiclaboratory.org/wiki/spectral-workbench-calibrationWell I'm interested in building one of these to play with. Will let you all know how it goes.--On Mon, Feb 4, 2013 at 12:49 PM, Mac Cowell <mac@diybio.org> wrote:
What do you all think about the Public Laboratory for Open Technology and Science (PLOTS) spectrophotometer design?They have developed instructions for building a basic spectrophotometer from a low-cost webcam, electrical-conduit housing, and a fragment of a DVD as a diffraction grating. Seems like the devil is in the details for something like this and they have paid a fair amount of attention to the details.Build instructions: http://publiclaboratory.org/wiki/dskWhat about calibration? I think I missed that step in their instructions...
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