38
Lansis
®
System Manual
Issue 1
EAR99
Technology
Subject
to
Restrictions
Contained
on
the
Cover
Page.
Note that the READOUT signal is:
•
LOW during Shutter Open/Close Compensation Times;
•
LOW during Exposure Time;
•
HIGH during Readout.
Since the shutter behaves like an iris, the opening and closing of the shutter will cause
the center of the CCD to be exposed slightly longer than the edges. It is important to
realize this physical limitation, particularly when using short exposures.
CAUTION!
!
A Shutter can overheat when short, rapidly repeated
exposures are used, or if the shutter is held open for an
extended period of time.
7.2
CCD Temperature
Lowering the temperature of the CCD generally enhances the quality of an acquired
signal. Temperature control is configured on the Sensor expander.
Once a Temperature Setpoint has been programmed on the Sensor Expander, the
software controls the camera's cooling circuits to reach the programmed array
temperature.
When the camera’s temperature has cooled to within ±0.5°C of the programmed
setpoint, Locked is displayed to the right of the target temperature in LightField’s status
bar. At this point, Lansis’s control loop will continue to reduce the thermal error,
typically holding the temperature to within ±0.05°C of the programmed setpoint.
The time required to achieve lock may vary considerably depending on factors such as
the camera type, CCD array type, ambient temperature, etc. Ultimate system stability is
achieved approximately 20 minutes after thermal loop locks. However, as long as
Lansis’s CCD has cooled sufficiently to image, focusing of the system can begin.
Typically, quantitative data may be acquired as soon as thermal lock is relatively stable.
If, however, an experiment requires exposure times in the 10 to 30 minutes range or
more, it is recommended that Lansis be permitted to cool for a longer period of time
before acquiring live data.
The deepest operating temperature for a system depends on the CCD array size and
packaging. Refer to
Table A-4, Default Operating Temperature
deepest cooling temperatures.
