Campbell Scientific CS135 Lidar Ceilometer - Manual (Page 13)

User Guide
5
The control system of the CS135 is divided into three modules, DSP, TOP and
PSU as follows:-
DSP is the main data processing and communications unit of the CS135.
TOP provides a number of safety shutdown features such as over and under laser
output level. It also contains the calibration circuitry and dirty windows system.
PSU controls the power supply, including battery charging and deep discharge
protection.
The CS135 has a rugged environmental enclosure that protects the instrument
from the harshest conditions and will measure the atmosphere with high stability
and repeatability.
Fig 2.2 Principle of operation
2.2 Optical Measurement
2.2.1 Optical Arrangement
The CS135 employs a novel split-lens design to increase optical signal to noise
ratio over other instruments while maintaining Class 1M eye safety by integrating
larger optics into a compact package (see Fig 2.2). This optical design provides an
alternative to traditional biaxial or common-optics designs. The optical isolation
of traditional biaxial systems is maintained to increase detector sensitivity, while
the low overlap onset height of common-optics systems is incorporated to allow
measurements at close ranges.
2.3 Internal Monitoring
The CS135 monitors a large number of parameters relevant to its performance.
These include window contamination, key voltages and currents and internal
temperature and relative humidity. Data messages, see Section 5, include this
information allowing remote diagnosis of the CS135 condition. In addition a
special status message can be polled.