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When you display the spectrograph there are numbers along the x and y axis but I can’t find labels as to what they represent? Anyone know?
The x axis is wavelength of light. If I remember correctly the y axis amplitude, but don’t quote me on this one.
The wave length makes sense for the x axis, but the y axis changes too much when normalizing. Without normalization 0 – .325 but after normalization its between -1.5 and + 1.5.
Hi,
I’m Guy , product manager of SCiO SDK.
Here are the answers:
- X is the wavelength represented in nm (nanometers).
- Y is dependent on the state of the toggle buttons in SCiO Lab.
When:
- No buttons selected: Raw reflectance spectrum
- Processed (only): Assumes Beer-Lambert model is valid, and transforms the measured signal to be linear with concentration by doing a log transform and adjusting the result for noise and deviations from the model. You can learn more about Beer-Lambert here: http://www.chemguide.co.uk/analysis/uvvisible/beerlambert.html
- Normalized (only): Performs normalization of the signal. This is meant to compensate for changing measurement conditions (e.g. varied scanning distances) that typically occur from sample to sample. Y axis still means reflectance but in normalized units instead of raw reflectance.
- Both Processed and Normalized: First assumes Beer-Lambert model (like processed) and then normalizes the results to compensate for differences in the optical path between samples. This is useful, for example, when there is variation in the thickness of the samples.
Typically, different models and types of samples will require different pre-processing methods. You should both choose the pre-processing method to match your experimental setup and optimize the performance of your model. If you planned and gathered your data correctly, these efforts will coincide.
Thank you, I now see where in the online documentation my question was answered… Its OK to say RTFM..
Where can I find the (online) documentation?
The online documentation is part of the SCiO Lab support suite that is available to users who receive their SCiO and the login credentials to SCiO Lab.
We are happy to answer any questions you may have on this forum, or via email at: dev@consumerphysics.com
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