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System Description
84
Spectrometer
Optical System
The Avio 500 optical design combines an echelle polychromator with a solid-state
detector in an integrated system optimized for ICP-OES. The detector is a custom,
two-dimensional CCD array. The plasma source is a radial view or a dual-view
(can be viewed either axially or radially) RF generator.
The polychromator has an echelle grating designed to use multiple diffraction
orders. To separate the orders and create a two-dimensional diffraction pattern, the
echelle grating is combined with a cross-dispersing element. In the ultraviolet
range, a cross disperser is used. On the Avio 500, a prism is also used in the visible
range.
The Segmented-array, Charge-coupled-device Detector (SCD), patented by
PerkinElmer, is a solid-state imaging device. It provides simultaneous detection
with simultaneous background measurement.
The detector was designed to provide:
•
high UV quantum efficiency.
•
wide photometric dynamic range.
•
random access data readout: subarrays are addressed individually and data is
read out sequentially using CCD (Charge-Coupled Device) transfer
techniques.
•
low noise characteristics, including low dark current noise.
The slit width has three different settings: High, Normal, and Low. High resolution
uses the narrowest slit; low resolution uses the widest slit.
The way in which the detector is read varies when different slits are chosen. With
High resolution, each pixel is read as two separate half-pixels. With Normal and
Low resolution, each pixel in the detector subarray is read as a whole.
Optics Housing
The optics are sealed and insulated in a tub-like enclosure. The inside of the
enclosure is temperature controlled by outside heaters to a temperature of 39
0
C.
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Troubleshooting
