Ocean Optics S1024DW Install - Manual (Page 20)

17
Light Sources: HG-1 Mercury Argon Calibration Source
The HG-1 M ERCURY A RGON C ALIBRATION S OURCE is a wavelength calibration source for UV-VIS-
Shortwave NIR spectrophotometric systems. The HG-1 produces Mercury and Argon lines from 253-922 nm,
for use in performing fast, accurate spectrometer wavelength calibrations. The HG-1 has an SMA 905
termination for connecting to optical fibers.
Caution!
! The beam emerging from the HG-1 produces ultraviolet radiation. Direct contact with the beam could
cause serious eye injury. Never look directly into the light source.
! The SMA connector may get HOT during operation.
! Dangerous voltages present. No user-serviceable parts inside.
! Never take apart the HG-1. The HG-1 contains mercury.
Operation
1. Plug the wall transformer end into a standard 110 V outlet. Plug the 12 V output end into the back of
your HG-1. Or, insert a 9V battery (not included).
2. Screw a fiber into the SMA connector on your HG-1. If your spectrometer does not have an entrance
slit, use a 50
µ
m diameter (or smaller) optical fiber. Larger fibers and slits will have lesser optical
resolution. Also, keep in mind that if the spectrometer has no slit and your experimentation involves
using optical fibers of different diameters, wavelength calibration will be necessary. Calibration is also
recommended each time you unscrew the fiber from the spectrometer.
3. Find the on/off switch next to the SMA connector and turn the lamp on. The red indicator will light
when the lamp is on.
Calibration
Users can perform wavelength calibration with a spreadsheet program such as Microsoft Excel, or a
calculator that performs polynomial regressions. The following describes how to calibrate the wavelength
of your spectrometer using the HG-1. 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. To recalibrate the wavelength of your spectrometer, just follow these simple steps.
What You Are Doing:
The relationship between pixel number and wavelength is a second-order polynomial . . .
λ
p
= I + C
1
p + C
2
p
2
. . . where
λ
is the wavelength of pixel p, I is the wavelength of pixel 0, C
1
is the first coefficient (nm/pixel)
and C
2
is the second coefficient (nm/pixel2). You will be calculating the value for I and the two Cs.
What You Will Need:
•
Your HG-1 Mercury-Argon lamp.
•
Your spectrometer.
•
An optical fiber. For spectrometers without a built in slit, a 50-
µ
m fiber works best.
•
Either a spreadsheet program (Excel or Quattro Pro, for example) or a calculator that performs second-
order linear regressions. (If you are using Microsoft Excel, select Tools | Add-Ins and make sure that
that Analysis ToolPak has been chosen.)