Chapter 3
Theory of Operation
Focus 30/35 Service Manual 3 - 16 P/N 79000035_SM, Version 1.5
infrared beam is transmitted from a Laser diode to the direction of a possible existing target prism. In
this search mode the telescope scans a predefined search window driven by the Servo drive system.
A target prism is found if the beam is reflected from a prism via the coaxial optics to the receiver. A
deviation to the centre pixel of the camera determines the horizontal and vertical direction to the
reflected infrared signal. It gives the Servo drive system the information to drive the instrument
sighting axis in to the center of the target prism. The status “target found “ is given and the tracking
mode is started to move the sighting axis exactly to the centre of the target prism.
The search mode is performed:
• automatically when camera starts in Auto Lock mode at actual telescope position
• automatically when target was lost in tracking mode by using a defined search window
• when target search was started manually by using a defined search window
The tracking mode is performed:
• automatically when in Auto Lock mode and a prism was found
• automatically when EDM tracking was started
Principle schematic of Tracker unit
Fig. 3-13 Principle of Tracker unit
Tracker transmitter diode
Tracker camera
Tracker mirror
Front lense prism
Tracker servo focus board
2°
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