Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
59
Description
The optical subassembly consists of the following major units: the conical
optical tube with fixture for the lens, a precise beam integrator block at the
lower end including a beamsplitter and a narrow-band filter, and a connection
flange for the laser transmitter and receiver subassemblies.
The receiver and transmitter subassemblies are factory-aligned and focused to
the optimum. They can be replaced any time by new assemblies without need
for readjustment. The adjustment necessary for the compensation of the
optical crosstalk after replacement of the receiver or transmitter subassembly
can be made by means of a graphical presentation on a maintenance terminal.
At the upper end of the optical tube is the Optics Monitor for control of the
laser performance, window contamination and temperature.
5.3.2 Laser Transmitter CTT21
Figure 5-6 CTT21 Block Diagram
Description
An unregulated supply voltage P65 is brought to the Laser Transmitter CTT21
and adjusted to a suitable level by means of an internal voltage regulator. The
laser diode of the subassembly is supplied with this regulated high voltage. A
trigger pulse is routed through a transformer to the trigger electrode of the
switching thyristor for driving a current pulse through the laser diode. A
special pulse-forming network makes this current pulse near-rectangular. A
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