Question: Can I get spatial resolution by making multiple parallel slits?

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dgidon asked on February 22, 2018 04:39
148 | 1 answers | #15799


Hello,

I'm trying to get some 1D resolution on the optical emission of a plasma jet. Is there any reason why I cannot make multiple parallel slits to get some spatial resolution? Looking at the images it seems to me that the broadening is small enough that it may be possible to visualize multiple points at once. Any thoughts?



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I don't think there's any particular reason you can't do that, but it will require you do some work: * Extracting the data would probably require that you crop out several ROIs. * The slist would probably need to be correctly spaced, too close and you would get the spectra to overlap, too far and they would be out of the FOV.

BTW: do note that as the slit used in the public lab spectrometer has a wide slit and not a point source you would get a 1D image, I'm guessing the spectral workbench is then integrating along the wavelength axis to improve the SNR, but you could re-write this code.

Do share your experience.


While one could construct two, parallel slits, no, that would not 'enhance resolution. A single slit is many, many wavelengths 'wide'. Assuming ideally-parallel light, the slit controls the number of diffraction grading ('DVD lines') being illuminated. Narrower single slits with very sharp edges are better. Wider/multiple slits and 'fuzzy' edges only add optical interference pattern distortion. As slit width decreases so does the total light intensity so with simple 'webcam' detectors, there are diminishing returns. For PLab-type devices, slit widths in the range of 0.1-0.15mm experimentally appears to be a good trade-off. PLab 'photo-film-slits' have limited edge-sharpness and their 'slit-space' has some random film emulsion spotting -- not dramatic but a pair of razor blades is experimentally, more optimal (if you can construct one accurately). https://publiclab.org/notes/stoft/10-03-2016/plab-3-proto-slit-upgrade might be helpful.


Totaly agree with @stoft.


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