INFICON Cool Drawer Single Sensor - Manual (Page 35)

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Cool Drawer Single and Dual Sensors Operating Manual
2.6 Shutter Operation
The shutter shields the crystal from molten pieces of material during the
preconditioning and conditioning phases of a process. A dual sensor head comes
standard with one shutter to protect the secondary crystal during the process.
2.6.1 Dual Sensor Head Shutter
INFICON dual sensor heads are designed to provide automatic crystal failure
backup or to provide separate crystals for use with two different materials. The two
crystals are located side-by-side in a water-cooled housing. Only one crystal is
exposed to the evaporation source. The other crystal is covered by the shutter. The
normally exposed crystal is the primary (crystal 1) and the covered crystal is the
backup (crystal 2). The shutter is moved by pneumatically actuating the bellows
assembly. When the pneumatic valve is open (on), the bellows is actuated which
moves the crystal shutter over crystal 1 to expose crystal 2.
2.6.2 Single Sensor Head Shutter
For the single sensor head type, a shutter covers the crystal. The shutter does not
fully cover the crystal at atmosphere, but once under vacuum, due to the differential
pressure, the shutter rests over the crystal. When the pneumatic valve is open (on),
the air actuates the bellows, which moves the shutter to expose the crystal.