Sinusoidally phase-modulated interference microscope for high-speed high-resolution topographic imagery.

We describe an interference microscope that produces topographic images with a minimum acquisition time of 20 ms. The system is based on phase-shifting interferometry with sinusoidal phase modulation induced by the oscillation of an interferometric objective (Michelson or Mirau). A CCD camera captures four images per oscillation period to produce a phase map in real time. The system is installed on a commercial microscope.