Abstract
Laser scanning microscopes based on optical heterodyne detection are reviewed. Optical heterodyne phase detection technique allows noncontact surface profile measurement with height sensitivity of the order of 1Å or even better. Combined with atomic force microscopy, the lateral spatial resolution of laser heterodyne phase micrscopy is much improved up to several Å, which enables atomic resolution imaging of a sample surface. On the other hand, optical heterodyne intensity detection technique has a unique feature of confocal imaging ability, and its high signal to noise ratio due to heterodyne detection allows us to observe 3 dimensional distribution of light scattering particles through an obstructing rough surface.
