Chapter 7
MCP-100 Option
57
SHUTTER OR CW/GATE
switch selects between Gate mode or Shutter mode. When
in Gate mode, the intensifier is normally off and a high voltage gate pulse is
needed to turn it on. When in Shutter mode, the intensifier is normally on with
no connection or a logic high (5 V) on the Shutter In BNC. A logic low (0 V) is
needed to turn it off.
BRIGHT CNTRL ON/OFF
switch turns the brightness control feature on or off.
Brightness control reduces the MCP gain when exposed to high light levels. This
compresses the output dynamic range to keep signal levels on screen during set-
up.
MCP POWER ON/OFF
switch turns the intensifier voltages on or off while chassis
power remains on.
INTENSIFIER H.V.P.S.
connector is used to supply High Voltage DC power to the
intensifier through the cable supplied by PI. The high voltage cable must always
be connected when power is on.
Hardware Overview
The MCP-100 option consists of a printed circuit board and a modular high voltage
supply which are mounted in the PG-200 chassis.
The MCP-100 contains circuitry for the following functions:
A variable high voltage power supply for the MCP voltage. MCP voltage is a linear
function of the programming voltage supplied by the keyboard of the PG-200.
Upper and lower limit circuits for the MCP voltage. (Normally set to -500 V and
-1000 V respectively).
Note:
When the image intensifier and MCP-100 option are purchased from Princeton
Instruments as part of the same order, the upper limit circuit will be set for the maximum
limit of the intensifier. The upper limit circuit also provides a slow turn-on during power-
up.
High voltage adjustment circuit for the voltage between MCP-Out and Phosphor
(normally set for -5500 V).
Alarm and shutdown circuit to shut down the high voltage and bring MCP voltage to
the minimum value if an over-current condition exists due to excessive light on the
Photocathode. This circuit automatically resets and retries after about 0.5 seconds.
Thus it will not prevent intensifier damage if excessive light is allowed to
continuously fall on the intensifier.
Automatic Brightness Control circuit to reduce the MCP voltage in response to
increasing light intensity on the Photocathode. This can be useful in focusing. When
properly interfaced to a PI CCD Controller, the Brightness Control circuit uses a
sample/hold to sample phosphor current during CCD exposure, and hold between
exposures. The sample/hold is inactive in the Gate mode. The Brightness Control
function is disabled for normal operation, since response is not linear (and may not
even be constant) when it is used.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com