INFICON Guardian EIES Controller - Manual (Page 103)

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Guardian Co-Deposition Controller Operating Manual
CAUTION
Be careful when bending fiber optic lines. Individual
internal fibers are easily broken, which reduces the light
signal at the output. Also, the detectors must be
supported by an external means. Do not hang the
detector from the Optical Beam Splitter fibers. Be sure
power to the PMT Detector Module is turned off whenever
the PMT is exposed to room light to avoid damage to the
PMT.
4.3.3.3 Optical Beam Splitter
For 2-material systems, two detectors can be mounted at the two outlets of one
beam-splitter. If there were no losses, half the original light signal would go to each
detector. In reality, light losses are significant and much less than half actually goes
to each detector.
Figure 4-11 shows a simplified schematic of an optical beam
splitting system for two detectors.
Figure 4-11 Beam Splitter
Beam splitters from Thorlabs are available with 1 in. (25 mm) threaded fittings to
mate with the Guardian detectors and flange couplings.
Multiple detectors and the associated optical components add size and weight to
the detection system. Sufficient clearance and support must be provided for all
these components. They cannot be supported by the vacuum feedthrough as in the
one-detector case. When installing the detector system, be sure to allow clearance
for maintenance of the sensor/feedthrough assembly.
For 3-material systems the signals reaching all three detectors are not the same
magnitude. Because of the additional beam split, detectors #2 & #3 each get much
less light than detector #1. The Guardian controller and software provide for gain
beam
splitter
optical
detect
PM
extension
tube
optical detect
PM