Camera Maintenance; Desiccant Exchange - Moravian Instruments G2 Series Mark II User Manual

Camera Maintenance

The G2 camera is a precision optical and mechanical instrument, so it
should be handled with care. Camera should be protected from moisture
and dust. Always cover the telescope adapter when the camera is removed
from the telescope or put the whole camera into protective plastic bag.

Desiccant exchange

The G2 camera cooling is designed to be resistant to humidity inside the
CCD chamber. When the temperature decreases, the copper cold finger
crosses freezing point earlier than the CCD chip itself, so the water vapor
inside the CCD chamber freezes on the cold finger surface first. Although
this mechanism works very reliably in majority of cases, it has some
limitations, especially when the humidity level inside the CCD chamber is
high or the chip is cooled to very low temperatures.
This is why a cylindrical container, filled with silica-gel desiccant, is placed
inside the camera head. This cylindrical chamber is connected with the
insulated cooled CCD chamber itself.
Warning:
High level of moisture inside the CCD cold chamber can cause camera
malfunction or even damage to the CCD sensor. Even if the frost does
not create on the detector when the CCD is cooled below freezing
point, the moisture can be still present. It is necessary to keep the CCD
chamber interior dry by the regular exchange of the silica-gel
desiccant. The frequency of necessary silica-gel exchanges depends on
the camera usage. If the camera is used regularly, it is necessary to dry
the CCD chamber every few months.
It is possible dry the wet silica-gel by baking it in the oven (not the
microwave one!) to dry it again. Dry the silica-gel for at last one or two
hours at temperature between 120 and 140 °C.
The silica-gel used in G2 cameras changes its color according to amount of
absorbed water – it is bright yellow or orange when it is dry and turns to
transparent without any color hue when it becomes wet. It is
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