LB1005 Operating Manual Getting Started
Bookham Revision 1 7
Chapter 2: Getting Started
This chapter explains the typical setup and operation of the LB1005 Servo
Controller. This chapter should help less experienced users rapidly adapt the
LB1005 to their specific servo application. Keep in mind that while the LB1005
has a flexible architecture that lends itself well to many feedback control
applications, not all types of operation can be adequately addressed in this
manual. The following are general guidelines for operating the LB1005, and
some deviation from these procedures may be required to meet specific
application needs. Demanding applications will require familiarity with
feedback control theory and good characterization of all system components.
The primary function of the LB1005 is to condition an input signal from a
detector and to provide an output signal to a transducer that controls a system
parameter. The output control signal forces the system parameter to a desired
value regardless of external disturbances, such as thermal fluctuations or
mechanical noise, which invariably affect the system. The difference between the
desired value and the actual value of the controlled parameter is typically called
the error signal. For instance, the parameter to be controlled might be the
intensity of a diode laser that has its optical output detected by a photodiode.
The LB1005 generates an error signal from the photodiode signal and then filters
this error signal to provide a control signal that changes the injection current to
the diode laser such that a stable optical power is maintained.
Typical Setup
The LB1005 is designed to easily integrate with other instruments and devices.
This section describes the various electrical signal connections that might be
made to and from the LB1005. Some typical signal connections between
common instruments are shown in Figure 3. Pay careful attention not to exceed
any damage thresholds when making connections between instruments.
NOTE: Before powering the LB1005, make sure that the fuse and voltage settings
are correct for your region’s wallplug electrical power (see the Electrical Fuse &
Voltage Selection section of Chapter 1.)
1. Detector output to LB1005 A & –B inputs: To provide feedback, the
parameter to be stabilized must first be detected. For example, a simple
photodiode might suffice for detecting optical intensity. For instances where
the laser wavelength is stabilized, spectrometers based on atomic/molecular
or interferometer resonances are needed to detect optical wavelength shifts.
The common characteristic of all detectors is that they produce a nonzero
slope that is locally monotonic around the desired lock point.
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