Ocean Optics NIR Series - Appendix A: Calibrating the Wavelength of the NIR Spectrometer; About Wavelength Calibration

Appendix A
Calibrating the Wavelength of
the NIR Spectrometer
This Appendix describes how to calibrate the wavelength of your spectrometer. Though each
spectrometer is calibrated before it leaves Ocean Optics, the wavelength for all spectrometers will drift
slightly as a function of time and environmental conditions.
About Wavelength Calibration
You are going to be solving the following equation, which shows that the relationship between pixel
number and wavelength is a third-order polynomial:
λ
p
= I + C
1
p + C
2
p
2
+ C
3
p
3
Where:
λ = the wavelength of pixel p
I = the wavelength of pixel 0
C
1
= the first coefficient (nm/pixel)
C
2
= the second coefficient (nm/pixel
2
)
C
3
= the third coefficient (nm/pixel
3
)
R
λ
= the reference intensity at wavelength λ
You will be calculating the value for I and the three Cs.
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