PerkinElmer Spotlight 400 Series, User Manual

Page: 41 / 120

Getting Ready to use the Imaging System . 41
Cooling the MCT Detector
When an MCT (Mercury Cadmium Telluride) detector is fitted in the imager, it must be cooled
to 77 K before you collect spectra. It is mounted in a dewar that can be filled with liquid
nitrogen. As you fill the dewar, the temperature of the detector drops, and the preamp
supplies power to the detector. Use the following procedure to cool the MCT detector.
WARNING
Do not site the instrument in a poorly ventilated area.
Oxygen depletion in an enclosed space does not trigger a gasping reflex,
and errors of judgment, confusion, or unconsciousness can occur in
seconds and without warning.
See
Location and Ventilation
on page 18.
WARNING
The extremely low temperature of liquid nitrogen can burn skin and eyes.
Avoid exposure by wearing heavy gloves and safety goggles whenever
you work with it.
WARNING
When liquid nitrogen warms to room temperature, nitrogen gas vaporizes
so rapidly that resulting pressures can send a funnel or detector cap
suddenly and forcefully shooting upward from the top of the imager.
WARNING
Be sure to wait the specified time when filling the funnel and before
replacing the detector cap. This enables the bubbling nitrogen to settle
down and the pressure to dissipate. In addition to wearing safety goggles
at all times, stand back from the imager after each time you fill the
funnel.