User`s manual

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

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high voltage to the image dissector tube may be increased. This adjustment is made on the back panel of the control unit

using a small screwdriver. For high light conditions, the high voltage may be reduced, or neutral density filters can be

placed in front of the lenses.

Note

The light source must be DC or the tracker will detect the 60 Hz change in light intensity.

Techniques of Targeting

There are many ways of illuminating and setting up targets. This section will deal with the two most common: front lighting

and back lighting.

Front Lighting

A target with a discrete light/dark interface can be illuminated from the front and the system can track it easily. If the object

under study does not have a built-in light/dark interface, you can tape or paint an interface onto the surface. The white

light/dark interface should be a flat, non-gloss surface. Make sure the intensity of the illumination is great enough to mask

any 60 Hz modulation from room lights, or turn down the room lights during operation of the system.

Figure 11

Back Lighting

Back lighting is best for illuminating dark or opaque targets. Placing a low-power lamp on the side of the target away from

the tracker produces a collimating or a silhouette effect. It might be necessary to place a light diffuser between the lamp and

the object to assure uniform illumination of the target. See Figure 12. Usually, the back-lit target offers a better signal-to-

noise ratio, and easier tracker focusing than other target configurations and has the further advantage of requiring less light

intensity.