User`s manual

Biaxial Displacement Follower User’s Manual Version 1.4, April 19, 2004 IM1013

Page

Figure 2

There are two possible target configurations for measuring target displacement along the vertical axis: light over dark and

dark over light. That means it must be possible to alter the phase of the current going through the deflection coils to deflect

the electron image back to its original locked-on position and not away from this center position. In the 5000 Series, the

target switch on the front panel of the control unit changes the phase. See Figure 3. Failure to set this switch to the target

configuration being tracked will cause improper deflection and render the system inoperative.

Figure 3

With the switch set to H (horizontal) mode, the system can track one target along the horizontal axis. V (vertical) mode

allows for tracking one target along the vertical axis. In MUX (multiplex) mode, multiplexer circuitry switches the tracker

back and forth between vertical and horizontal tracking. Hold and shift amplifiers in the servo loop remember the last target

position. Deflection amplifiers are driven by the two hold amplifiers. As a result, the time required for the tracker to move

from vertical to horizontal is a function only of the system slew rate, which is approximately 3 microseconds. Two data

Demultiplex Filter

Deflection

Servo Amp

Optical

Head

Vertical

Horizontal

Photo-Tube

Preamp

Velocity

Converter

model 5600

Block Diagram

Sample/Hold

Multiplex