Displacement Follower User’s Manual
Version 1.4, April 19, 2004
IM1008
Page 9
Targeting
Target Requirements
The 5000 Series operates by locking onto a sharp discontinuity in the intensity of an object’s reflected or emitted light. The
target is actually the edge that can be seen at the light-dark interface and can be made up of any combination of reflected,
absorbed, or emitted light. The contrast in light intensities should be at least three to one. The greater the contrast, the easier
it is to obtain lock-on and the less system output noise is produced. In general, any target whose discontinuity can be
observed visually can also be tracked electro-optically. Select the target configuration using the Target Phase switch on the
front panel of the control unit.
Figures 6, 7, 8
and
9
show some examples of possible target configurations.
Figure 6 Figure 7
Figures 6
and
7
represent targets with configurations: of light over dark and dark over light, respectively. The 5000 Series
can measure vertical displacement for both configurations.
Figure 8 Figure 9
Figures 8
and
9
represent targets with light to the left of dark, and dark to the left of light, respectively. The 5000 Series can
measure horizontal displacement for both configurations.
Target Illumination
If the light portion of the target is not bright enough, lock-on is not possible. The amount of light can be read with the built-
in light measuring system. See
Operating Procedures
, page 16. If the light intensity of the target is beyond the adjustable
range of the lens diaphragm—either too bright or too dim—other adjustments are available. For low light conditions, the
high voltage to the image dissector tube may be increased. This adjustment is made on the back panel of the control unit