Scanning microscope with orthogonally displaced scanning head

摘要

The microscope has a scanning head which is displaced in orthogonal directions relative to the surface of the scanned microscope sample. A defined gap is maintained between the scanning head and the sample surface. The scanning signals for both orthogonal directions are provided by a scanning signal generator (78) and used to provide corresponding drive currents for displacement of the scanning head. A proportional-integral control (76) is used to maintain the required spacing gap using a further positioning drive acting in a direction perpendicular to the scanning drives in response to a proportional-integral signal representative of the spacing gap. The drive currents are limited by the magnification factor.