Optical microscope with nanometer longitudinal resolution based on a Linnik interferometer

Abstract: A microscope based on the Linnik interferometer was designed, built, and tested. Two methods were used for interference pattern measurement: phase-shifting and polarized single-shot methods. The former uses a low coherence light emitting diode as a light source, providing 10 nm resolution in the Z direction and diffraction-limited resolution in the X and Y directions. The second method is insensitive to vibrations and enables observation of moving objects. The simplicity and low cost of this instrument make it valuable for a variety of applications.