Ocean Optics S2000 - Manual (Page 49)

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.
Never take apart the HG-1. The HG-1 contains mercury. Dangerous voltages present. No user-serviceable
parts inside.
! !
The SMA connector may get HOT during operation.
Setting Up
To re-calibrate the wavelength of your spectrometer, you will need the following:
" The 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 third-order
linear regressions. If you are using Microsoft Excel, choose Tools | Add-Ins and check AnalysisToolPak and
AnalysisToolPak-VBA
Operation
1. Plug the wall transformer end of the HG-1’s power supply 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. Attach a fiber from the spectrometer 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 with each fiber you anticipate using 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
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
2
p 3
where
λ
is the wavelength of pixel p, I is the wavelength of pixel 0, C
1
is the first coefficient (nm/pixel), C
2
is
the second coefficient (nm/pixel 2 ), and C
3
is the third coefficient (nm/pixel 3 ). You will be calculating the value
for I and the three Cs.
Light Sources: HG-1
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