
1100 Series DAD and MWD Reference Manual 229
Introduction to the Detector 6
Optical System Overview
Optical System
The optical system of the detector is shown in Figure 57. Its illumination
source is a combination of a deuterium-arc-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 achromat (source lens) forms a single, focused beam of light
through the flow cell. Each cell room and lamp are separated by a quartz
window which can be cleaned or replaced. In the spectrograph, light is being
dispersed onto the diode array by a holographic grating. This allows
simultaneous access to all wavelength information
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 low-pressure
deuterium gas, the lamp emits light over the 190-nm to approximately 800-nm
Figure 57 Optical System of the Detector
Tungsten lamp
Deuterium lamp
Holmium oxide filter
Achromat (source lens)
Flow cell
Slit
Diode arra
Grating
Cell suppo
window
Spectro le
Coupling lens
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