What I want to do
replicate the results of my previous note using different other cameras. I want to know if the shift in the location of a spectra's peak from blue-green as a measure a series of heavy-to-light oils is reproducible. I took the spectra in the previous research note with a Syba camera that shipped in our first and second Desktop spectrometry kits, Here I compare to the Sanm camera found in the current Desktop Spectrometer and the infragram Webcam.
I want to see a replication of this pattern, where heavier = bluer. preferably at the same location.
- 5W-30 has a peak at 444nm
- 20W-50 at 436-8nm
- 80W-90 at 432-435nm
My attempt and results
I started measuring the styrene cuvettes I'd used in my previous trials, but some of them were melting (yes, melting) from contact with the oils and especially the diesel.
The Infragram Webcam has been deconstructed, and its blue filter removed, and the surface of the CCD cleaned off with denatured alcohol. Its focal length is set to 9." It is quite a bit more sensitive than the syba cam, and produces bright spectra. That becomes an issue. It could perhaps be attenuated with an optically-printed slit. It seemed like I got a lot of "blown out" spectra.
I tried some spectra through a polarized grating to attenuate it. it seemed to match the dimmer spectra taken off-center from the fluorescing oil.
just looking at and trusting (becuase they look nice) the lower peaks, I'm not able to grade the oil:
I'm not really seeing a clear difference in the peaks between diesel and crude either:
the crude peaks, even the "clearest" looking ones between syba, sanm, and infragram cameras are all different.
comparing crude to diesel on each leads to differing conclusions. The infragram camera and sanm cam both have a bluer peak fro diesel than crude, the opposite of what I'd expect, and neither is in the same place.
Questions and next steps
testing all the other cameras I have here built into spectrometers.