Ocean Optics Nirquest Install - Manual (Page 24)

A: Calibrating the Wavelength of the Spectrometer
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• A light source capable of producing spectral lines.
Ocean Optics’ AR-1 Argon lamp or HG-1 Mercury-Argon lamp are ideal for this purpose. If you
do not have an AR-1 or HG-1, you will need a spectral line source that produces several (at least
4-6) spectral lines in the wavelength region of your spectrometer.
If an order-sorting filter is installed in the NIRQuest, the XE-1 Xenon lamp is necessary to
perform the wavelength calibration.
• The NIRQuest Spectrometer.
• An optical fiber (for spectrometers without a built-in slit, a 50-
µ m fiber works best).
• A spreadsheet program (Excel or Quattro Pro, for example) or a calculator that performs third-
order linear regressions.
• If you are using Microsoft Excel, choose Tools | Add-Ins and check AnalysisToolPak and
AnalysisTookPak-VBA.
Calibrating the Wavelength of the Spectrometer
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Procedure
Perform the steps below to calibrate the wavelength of the spectrometer:
1. Place SpectraSuite into Scope mode and take a spectrum of your light source. Adjust the
integration time (or the A/D conversion frequency) until there are several peaks on the screen that
are not off-scale.
2. Move the cursor to one of the peaks and position the cursor so that it is at the point of maximum
intensity.
3. Record the pixel number that is displayed in the status bar or legend (located beneath the graph).
Repeat this step for all of the peaks in your spectrum.
4. Use the spreadsheet program or calculator to create a table like the one shown in the following
figure. In the first column, place the exact or true wavelength of the spectral lines that you used.
In the second column of this worksheet, place the observed pixel number. In the third column,
calculate the pixel number squared, and in the fourth column, calculate the pixel number cubed.