TopBox User Manual
Table of Contents
Fig. 1. Left: The TopBox autoguider assembly.
Right: Interior detail of the pickoff mirror, focuser, and sliding stage.
The TopBox autoguider assembly is a traditional offset guider (sometimes called
an off-axis guider) consisting of a diagonal pickoff mirror which directs light
from the telescope to a small CCD camera externally mounted in a motorized
focuser. These components are connected together as a single unit mounted on
the moving stage of a motorized linear positioner, allowing guide stars to be
selected from regions far enough to the E and W of the main CCD camera field of
view to avoid vignetting by the pickoff mirror. To maintain alignment of the
sliding optical assembly, the top end of the focuser mounting bracket is
attached to a linear bearing that slides along a rail built into the frame of
the TopBox. As shown in Fig. 2 below, the focuser protrudes through a set of
sliding light baffles which it carries along as it moves back and forth in the
Fig. 2. Sliding baffle system for the autoguider focuser and camera.