Ocean Optics HR4000CG-UV-NIR - Manual (Page 21)

Appendix A
Calibrating the Wavelength of
the HR4000
Overview
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. Ocean Optics recommends periodically recalibrating the
HR4000.
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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