We present a phase-imaging method with an axial range that can in principle be arbitrarily large compared to the wavelength and does not involve the usual phase unwrapping by detection of phase discontinuity. The method consists of the generation and combination of two phase maps in a digital holography system by use of two separate wavelengths. For example, we reconstructed the surface of a spherical mirror with ~10-nm axial resolution and an axial range of ~3μm .
© 2003 Optical Society of America
(090.1760) Holography : Computer holography
(090.2880) Holography : Holographic interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(180.3170) Microscopy : Interference microscopy
(180.6900) Microscopy : Three-dimensional microscopy
J. Gass, A. Dakoff, and M. K. Kim, "Phase imaging without 2π ambiguity by multiwavelength digital holography," Opt. Lett. 28, 1141-1143 (2003)