| 摘要 |
An optical system for determining the position and/or orientation of an object (10), for example, a freely suspended rotatable polygon mirror, comprises a convex mirror (24) on the rotation axis (11) of the polygon mirror and a plane mirror (25) perpendicular to the rotation axis. A convergent radiation beam is projected on the convex mirror (24). The reflected radiation is subsequently focused on a detection system (40, 45) via an astigmatic imaging system (75, 78, 51). A substantially parallel radiation beam is incident on the plane mirror (25), which beam, after reflection, is also focused to a radiation spot (34a) on the detection system (40, 46). The position and the shape of the radiation spots (34, 34a) are a measure of the position and the orientation of the polygon mirror (10). After processing, the output signals of the radiation detection system are applied to elements (91), for example electromagnets for stabilizing the polygon mirror (10). <IMAGE> |
