| Details: |
The main challenge in generating intrinsic contrast from optically thin specimens including live
cells is that, generally, they do not absorb or scatter light significantly. Phase contrast
microscopy represented a major advance in intrinsic contrast imaging, as it revealed inner details
of transparent structures without staining or tagging. While phase contrast is sensitive to minute
optical path-length changes in the cell, down to the nanoscale, the information retrieved is only
qualitative. Quantitative phase microscopy (QPM) has recently become an active field of study
and various experimental approaches have been proposed. QPM reveals intrinsic contrast of
cell/tissue structures and also renders quantitative optical path-length maps across the sample. It
is also used for characterizing materials, semiconductors etc. However, as most of the QPM
systems have coherent illumination (laser, for example), the contrast of quantitative phase
images (QPI) is much degraded due to speckle noise and hence the spatial sensitivity.
In the presentation, I’ll show few white light based QPM systems for fast, label-free, high
sensitivity and high resolution measurements of biological samples: white-light diffraction phase
microscopy (wDPM), spatial light interference microscopy (SLIM), white-light Fourier phase
microscopy (wFPM). These systems are spatially and temporally highly sensitive because of
white light illumination and their common path geometry, respectively and they developed as
add-on modules to commercial microscope for best quality images. I’ll also show few recent
engineering and material science applications of the QPM. |