Phase Imaging Digital Holography for Biological Microscopy

摘要

The digital holographic microscopy is being developed, to offer a number of significant advantages and capabilities in phase imaging. The direct availability of both the amplitude and phase information offers a range of versatile processing techniques that can be applied to the complex field data, including the phase imaging which is particularly straightforward in digital holography. One of the techniques we are developing addresses the problem of 2-pi phase discontinuity in the phase image, where most of the conventional phase unwrapping algorithms require subjective intervention for multi-lambda discontinuity. In the present system, we generate two phase maps by digital holography using two different wavelengths. Numerical superposition of the two phase maps results in a new phase map whose effective wavelength is inversely proportional to the difference of the two wavelengths. The axial range can in principle be arbitrarily large compared to the wavelength, while maintaining axial resolution to a fraction of wavelength. We apply the phase imaging digital holography to a number of systems, including the imaging of thin films and biological cells. Preliminary results from these experiments are presented and future development and applications are discussed.