A technique to perform two-wavelengths digital holographic microscopy (DHM)
measurements with a single hologram acquisition is presented. The vertical measurement
range without phase ambiguity is extended to the micron-range, thanks to the resulting
synthetic wavelength defined by the beating of two wavelengths with a separation of about
80nm. Real-time dual-wavelength imaging is made possible by using two reference waves
having different wavelengths and propagation directions for the hologram recording. The …

We report on a method to achieve real-time dual-wavelength digital holographic microscopy
with a single hologram acquisition. By recording both interferograms from two laser sources
at different wavelengths in only one spatially-multiplexed digital hologram, we are able to
independently propagate and apply numerical corrections on both wavefronts in order to
obtain a beat-wavelength phase map of the specimen. This beat-wavelength being up to 10-
100 times larger than the original wavelengths, we are in a situation where the 2π phase …