Specifications

36 ST-133/ST-133A Controller Manual Version 2.H
Cooling (TE, RTE, PI-MAX)
These cameras are ordinarily equipped with a multi-stage Peltier type cooler that is
thermally coupled to the CCD. This device uses injected current to draw heat away from
the CCD surface. The heat is sequentially transferred through the Peltier stages and from
there to the outer shell of the camera via a heat transfer block. The method used to
remove the heat from the camera depends on the camera type. In the case of RTE/CCD
cameras, fins on the body of the camera radiate the heat to the surrounding atmosphere.
In addition, there is provision for optional air cooling via an accessory fan for enhanced
cooling performance. A cooling fan is standard in the PI-MAX camera. In the case of
TE/CCD cameras, liquid coolant can be circulated through the camera to remove the
heat, and there is provision for optional air cooling via an accessory fan. There are also
cameras in which air cooling is standard.
Cooling (LN)
LN/CCD detectors have several sections. The front enclosure contains the CCD array
seated on a cold finger. This finger is in contact with the LN Dewar and has a heater to
regulate the CCD temperature. The front enclosure opens into the vacuum jacket that
surrounds the internal LN Dewar.
LN/CCD detectors use liquid nitrogen to reduce the temperature of the CCD. The liquid
nitrogen is stored in a Dewar that is enclosed in a vacuum jacket for minimal external
thermal losses. The chip temperature is regulated by a heating element driven by closed-
loop proportional control circuitry. A thermal sensing diode attached to the cooling block
of the detector monitors the chip temperature. The temperature can be controlled over a
40° to 50° range Celsius. The exact range depends on the CCD device, as indicated in the
Table 2.
CCD Model Approximate Range
1024HER, 1024EHRB -50°C to -100°C
All other arrays. -80°C to -120°C
Table 2. Approximate temperature range vs. CCD model
LN/CCDs, because of their low operating temperatures, must always be connected to an
operating controller. If the controller power is turned off with liquid nitrogen remaining
in the Dewar, the CCD will quickly become saturated with charge, which cannot be
readily removed without warming the detector to room temperature.
Never remove the detector’s front window; ice will form immediately, destroying the
array. Operations requiring contact with the device can only be performed at the factory.
Never operate the detector cooled without proper evacuation. This could destroy the
CCD!
CAUTION
WARNINGS