Ocean Optics Question of the Week

Q.
What is the difference in the shape of spectra obtained by SpectraSuite vs. OmniDrived based applications?

A.
Users who develop applications using OmniDriver may produce spectra which, when graphed, look significantly different than the “same” spectra displayed by SpectraSuite.  If all conditions are identical, the graphs of spectra should match between SpectraSuite and OmniDriver-based applications.  Here are a few things to check for:

1.    Lighting conditions.  Make sure both spectra were obtained with identical lighting conditions.  It should be possible to run SpectraSuite and the OmniDriver App at the same time to eliminate any differences in lighting conditions.  But even if SpectraSuite and the OD app are not running concurrently, you can ensure that the lighting conditions are stable by watching the spectra graph in SpectraSuite for a period of time and ensuring that the graph is not changing.

2.    Integration Time.  Make sure the integration time matches between SpectraSuite and your OD application.

3.    Electric Dark Correction.  Make sure that both SpectraSuite and the OD app are using the same setting for this option.

4.    Mode.  Make sure SpectraSuite and the OD app are effectively running in the same “mode” (i.e. “scope”, “scope minus dark”, “absorbance”, “transmission”, etc.  It is best to start comparing spectra in “scope” mode, because this has the fewest variables involved that might impact the shape of the spectrum graph.

5.    If you are comparing spectra between SpectraSuite and your OD app in “scope minus dark” mode (or any other mode that depends on a dark spectrum, make sure that the lighting conditions were identical for both SpectraSuite and your OD app when you captured the dark spectrum.

6.    The same goes for “reference” spectra.  Make sure the lighting conditions are identical between SpectraSuite and your OD application when you captured the reference spectrum.

7.    Nonlinearity Correction.  Be sure the setting for this feature in SpectraSuite matches what your OD app is doing.

8.    Stray Light Correction.  Again, be sure the setting for this feature in SpectraSuite matches what your OD app is doing.

There are a few settings which cannot affect the basic shape of a spectrum graph.  They will only impact the noise level or “smoothness” of the graph.
1.    “Scans to Average”
2.    “Boxcar Width”

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