Stereo Scan 440 - DCU

The specimen chamber of the Slereoscan 440 holds the specimen to be viewed in
such a way that it may be freely manoeuvred during examination. The ~n
stage which holds the specimen is attached to the door of the chamber and may
be of the normal cartesian type or the Optional eucentric type. The cartesian stage
pennits movements of lOOmm in both X and Y directions, 3Omm in the Z
direction, 0 to 9(}° tilt and 360° rotation. Control of the stage move~nts may be
either manual, from the front of the stage door. or motorised using the Optional
stage motorisation package. The stage may be opened for examination once the
vacuum within the chamber has been released.
1.1.2. The Vacuum System
The operation of the electron optical column and specimen scanning is dependent
not only on the presence of a vacuum, but also the degree of vacuum, i.e. the
system is safely interlocked so that it is not possible to switch on any of the high
voltages until an adequate vacuum is reached.
The vacuum system is simple and efficient. A turbomolecular pump, backed by a
rotary pump, is mounted on the lower face of the specimen chamber and
commences pumping when the system is being evacuated and comes to rest
during system venting. The electron gun and column are pumped through the
tube running from the left side of the chamber up to the gun section. The only
valve in this system is the air-admittance valve attached to the rear of the
chamber, which automatically opens when venting is requested. Normal
operating vacuum should be in the range to 10-4 to 10-6 torr. No water cooling is
required.
If the lanthanum hexaboride option is fitted. a greater degree of vacuum is
required in the gun section and for this reason provision is made to independently
pump the gun and column to a level of about 10-7 torr using an ion-getter pump
The pump is mounted on the rear of the gun section and the column may be
isolated during specimen exchange by the two valves associated with the LaB6
option.
1.1.3. The Control Console
Complete software control of the Stereoscan 440 ~ that operation of the
instrument is rather like operating a desktop computer - all operations are
controlled through the moose and keyboard. Within the console of the
microscope, the computer is used to communicate your operations and commands
into actions by the SEM. The PC environment used is Microsofi@
WindowslM 3.11 and the SEM control application (LEO) runs within this well
known and easy to use system. Section 1.2 provides an introduction to
Window~ and how to use the system of Help provided. If you are unfamiliar
Stereoscan 440 Operator Manual