Related Experiment Video
Updated: Jun 6, 2026

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization
Published on: July 5, 2016
Dual-wavelength heterodyne differential interferometer for high-precision measurements of reflective aspherical
Abstract:
A dual-wavelength heterodyne differential interferometer was developed and tested together with scanning mechanics. To extend the range of unambiguity, two wavelengths were applied. This is important for measuring structures with surface discontinuities (reliefs, steps). The automatic adjustment of the interferometer with respect to the rotational symmetrical measuring surfaces (aspheres) is important. An adjustment is needed to scan the asphere through its vertex. Typical measurements on a sphere, an asphere, and steps are shown.
Related Concept Videos
Differential Leveling
IR Spectrometers
Electronic Distance Measuring Instruments

