Pco dicam C1, Руководство пользователя

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2.1 SAFE USE OF IMAGE INTENSIFIER
LIGHT DAMAGES IMAGE INTENSIFIER
Too much light input during exposure time (gate=ON) lowers the
lifetime of the image intensifier.

Be careful with all kinds of light sources, a few milliseconds
can be enough to damage the image intensifier irreversibly.
Working with Image Intensifiers: Safety Instructions
The camera contains a highly sensitive image intensifier. To avoid
damages or loss of quality, the camera should not be operated with
too high light input. The photocathode’s lifetime and its loss of
sensitivity depend directly on the amount of light impinging on it
during exposure time. A few milliseconds or even microseconds of
exposure time may be sufficient to damage the photocathode if the
light source is powerful enough. The photocathode is a few µm thin
layer of a photo sensitive material. It absorbs photons and in turn
generates photoelectrons for amplification in the Micro Channel Plate
(MCP). In case the photoelectron generation rate is too high due to
intense light input, the photocathode might be eroded. In extreme
cases the layer completely wears off and there a black spot appears.
The photocathode is now ‘blind’ and there is no remedy except
replacing the complete image intensifier tube. Bright light sources,
e.g. lamps or daylight (for example while adjusting or focusing the
camera) in a long exposure operation mode can permanently damage
the photocathode, even when a monitor does not show any picture
(if, for instance the
Intensifier Voltage
MCP-Gain is set to minimum).
Since the MCP is behind the photocathode, changing the MCP-Gain
does not affect the load of the photocathode. It is a wrong conclusion
to assume lower MCP-Gain would save the photocathode in an
overexposed scene. The opposite is true.
Therefore for a safe camera operation we recommend to start with a
nearly closed iris (high f-stop, e. g. 22), short exposure time and
maximum MCP-Gain value (Image
Intensifier Voltage
set to
maximum). If no image is visible to yield an image the exposure time
may be carefully increased or the iris opened step by step.
If the camera is not in use replace the cap in front of the lens or
intensifier.
Operational Lifetime Values
The manufacturer of the image intensifier tube specifies durability for
continuous, non-gated operation only:
The half-life of the image intensifier (time taken for a 50% decrease in
sensitivity) is approximately 2000 hours at a light input of 1 mlx. 10-
times higher light input reduces the half-life to approximately 200
hours.
In the gated mode a linear correspondence of half-life and light input
does not apply.
In this case substantially higher light inputs are allowed.
NOTICE
NOTICE
NOTICE