User`s manual

Biaxial Displacement Follower User’s Manual Version 1.4, April 19, 2004 IM1013
Page
10
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 7, 8,9 and 10how some examples of possible target configurations.
Figure 7 Figure 8
Figures 7and 8 represent targets with configurations: of light over dark and dark over light, respectively. The 5000 Series
can measure vertical displacement for both configurations.
Figure 9 Figure 10
Figures 9and 10 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 17. 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