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Topic: Reflectance spectra analysis  (Read 123 times)

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Offline RedTomas

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Reflectance spectra analysis
« on: May 17, 2020, 09:18:16 AM »
Hi, I was wondering how one should interpret reflectance spectra measurements. I've never done any work with color measurements, so it's really annoying now when I try to understand what i've measured.

First graph is berry extract dilution measured with konica minolta cm-700d spectrophotometer, when chosen wavelenghts were 360-740.I would assume that the color of this is purple https://gyazo.com/3784f75d2a3ef7561989311c71ed8455, however what color would this be https://gyazo.com/75560319e0fa8e7f5414d5ae554e269d

Are these graphs supposed to represent color or what, at this point I'm really confused, because I have no idea why I did these measurements lol

Offline Corribus

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Re: Reflectance spectra analysis
« Reply #1 on: May 18, 2020, 10:07:40 AM »
I can't access the data you posted, but I'll just add a note that it's difficult to relate spectral absorbance or reflectance data with visual color. For one, the color you perceive is due to a combination of reflected, absorbed, and emitted wavelengths that your eye collects. We might say that light of 540 nm is "green", but rarely does monochromatic light reach your eyes. Your brain interprets the mixture of wavelengths your eyes detect as a certain color, but it's hard to take a look at a complex spectrum and say, "that's gonna look purple". This puts aside the fact that what one person calls purpl(ish), another may call red(dish).

For this reason, color is usually expressed on a L*ab scale, and is measured using a colorimeter, not a spectrophotometer. 

But certainly, if you don't know why you did whatever experiments you did, no amount of information we provide is likely to help you.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline RedTomas

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Re: Reflectance spectra analysis
« Reply #2 on: May 18, 2020, 01:31:09 PM »
But certainly, if you don't know why you did whatever experiments you did, no amount of information we provide is likely to help you.
You see the point of this measurement was to see how different concentrations of added compound affect reflectance spectre, however because of Corona virus, I'm left with unfinished measurements. I just can't grasp what reflectance spectre shows, what information I can attain by looking at such graph. Color was not the reason the measurements were made, however that's how I'm trying to interpret it. Its probably bad assumption from my side.

This is what finished experiment looks like, however only thing I can deduce from this is that L* value is lower the more compound is added, so maybe lower reflectance % corelates with L* . Maybe someone with more experiance in would see more
« Last Edit: May 18, 2020, 01:44:45 PM by RedTomas »

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