Agilent Technologies 8453 Operator's Manual page 125

Figure 1
Cuvette
Source lens
Slit
Grating
Theory of Operation
Optical System Overview
Optical System Overview
Optical System
The optical system of the spectrophotometer is shown in Figure 1. Its
radiation source is a combination of a deuterium-discharge lamp for the
ultraviolet (UV) wavelength range and a tungsten lamp for the visible (VIS)
and short wave near-infrared (SWNIR) wavelength range. The image of the
filament of the tungsten lamp is focused on the discharge aperture of the
deuterium lamp by means of a special rear-access lamp design which allows
both light sources to be optically combined and share a common axis to the
source lens. The source lens forms a single, collimated beam of light. The
beam passes through the shutter/stray-light correction filter area then
through the sample to the spectrograph lens and slit. In the spectrograph
light is dispersed onto the diode array by a holographic grating. This allows
simultaneous access to all wavelength information. The result is a
fundamental increase in the rate at which spectra can be acquired.
Optical System of Spectrophotometer
Lamps
The light source for the UV wavelength range is a deuterium lamp with a
shine-through aperture. As a result of plasma discharge in a low pressure
deuterium gas, the lamp emits light over the 190 nm to approximately 800 nm
wavelength range. The light source for the VIS and SWNIR wavelength range
is a low-noise tungsten lamp. This lamp emits light over the 370 nm to
1100 nm wavelength range.
Shutter/stray
light filter
Tungsten
lamp
Deuterium
lamp
Source lens
Photodiode
array
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