Differential phase contrast (DPC) is a quantitative phase imaging technique which measures the sample’s phase derivative by taking two images from complementary asymmetric illumination patterns. Distinct from coherent techniques, DPC relies on partially coherent illumination, providing 2× better lateral resolution, better optical sectioning, and immunity to speckle noise. In this paper, we derive the weak object transfer function to quantify how sample’s phase is converted into our DPC measurements, then develop quantitative inversion methods. Phase reconstructions from single-axis DPC measurements suffer from missing frequencies along the axis of asymmetry. We measure the missing frequency information by taking DPC measurements from other axes. Our phase reconstruction method provides a unified framework for both single and multi-axis DPC measurements. We implement our DPC measurements in real-time and along arbitrary axes of asymmetry by computational illumination on an LED array microscope.

Date Published: 11 March 2015
PDF: 6 pages
Proc. SPIE 9336, Quantitative Phase Imaging, 93360A (11 March 2015); doi: 10.1117/12.2078286

Published in SPIE Proceedings Vol. 9336:
Quantitative Phase Imaging
Gabriel Popescu; YongKeun Park, Editor(s)