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Chapter 7
Calibration
Overview
This chapter provides information for performing your own wavelength calibration and
irradiance calibration.
An EEPROM flash memory chip in each Flame contains wavelength calibration coefficients,
linearity coefficients, and a serial number unique to each individual spectrometer. The
spectrometer operating software application reads these values directly from the spectrometer,
enabling the ability to “hot-swap” spectrometers between computers without entering the
spectrometer coefficients manually on each computer.
USB Programmer software is freely available from Ocean Optics:
http://oceanoptics.com/support/software-downloads/. This software can be used to
write calibration coefficients to the spectrometer and reload firmware if the spectrometer
becomes corrupted.
Wavelength Calibration
This section 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 Flame.
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:
p
=
I
+
C
1
p
+
C
2
p
2
+
C
3
p
3
Where:
= 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
)
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