White Light Diffraction Phase Microscopy (wDPM)

Posted on March 1, 2012 by mmir2

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Quantitative Phase Imaging (QPI), i.e. mapping the phase distribution of an image field, has become a rapidly emerging area of study.  The range of QPI applications in biology includes red blood cell imaging, cell growth, cell refractive index, optical properties of tissues etc. Diffraction Phase Microscopy (DPM) is a common-path interferometric method that was developed to provide highly stable phase measurements without degrading the diffraction limited resolution. However, due to the speckle generated by the high temporal coherence light typically employed in QPI (including DPM), the contrast (or, more accurately, contrast to noise ratio) has not matched that achieved by white light techniques, e.g. phase contrast microscopy (PCM). Recently we have developed white-light Diffraction Phase Microscopy (wDPM) as a new method that combines the benefits of stability associated with DPM and diminished speckle effects due to white light illumination. This novel method has significant benefits compared to existing approaches, such as lack of speckles due to white light illumination, add-on capability to a commercial inverted microscope, multimodal investigation potential due to overlaying with other modalities of the microscope, spectroscopic potential due to the broad band light, single shot phase imaging, millisecond-scale acquisition time and high stability insured by the common path geometry. The capability of wDPM system is illustrated in the figures below for the imaging of HeLa cell and Microglia cell.