We propose dual-wavelength digital holographic microscopy with a slightly
off-axis configuration. The axial measurement range without phase ambiguity is
extended to the micrometer range by synthesizing a beat wavelength between the
two wavelengths with separation of 157 nm. Real-time measurement of the
specimen is made possible by virtue of the high wavelength selectivity of the
Bayer mosaic filtered color CCD camera. The principle of the method is exposed,
and the practicability of the proposed configuration is demonstrated by the
experimental results on a vortex phase plate and a rectangular phase step.
© 2012 Optical Society of America
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