PerkinElmer AAnalyst 700, User Manual

Page: 124 / 194

Spectrometer System Description
7 -6
0993-5255
The optical system
The AAnalyst 700 uses a double-beam optical system as depicted in Figure 7-1.
Front-surfaced, reflecting optical components are used throughout. The mirror
surfaces are coated with silica for durability.
The lamp compartment has positions for up to eight spectral sources. The
radiation from the requested source lamp is reflected by a movable mirror into the
optical path.
A beam splitter splits the radiation into a sample beam and a reference beam. The
sample beam passes through the atomizer while the reference beam passes around
the atomizer and is conducted by a fiber optic. The sample and reference beams
are measured simultaneously.
The Littrow-configuration monochromator has a large area reflecting grating
blazed a two wavelengths; 236 nm for operation in the UV spectral range and
597 nm for operation in the visible spectral range. The monochromator offers a
choice of three spectral slit widths. Two slit heights are available for each slit
width. The high slits are used with the flame technique while the low slits are used
with the graphite furnace technique. The detector is a segmented array of discrete
photodiodes.
For continuum source background correction, the radiation from the deuterium
lamp is merged with the source radiation at the beam splitter.