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Proceedings Paper

Quantitative phase imaging by pupil modulation different phase contrast (PMDPC) (Conference Presentation)

Paper Abstract

Differential phase contrast (DPC) is a non-interference quantitative phase imaging method achieved by asymmetric optical systems. Quantitative DPC images are achieved previously with asymmetric illumination systems. However, it works well for on-focus thin samples only. Considering the limitation, we develop a pupil modulation differential phase contrast (PMDPC) imaging method. Instead of modulating the illumination, we use a spatial light modulator (SLM) to modulate a 4f imaging system’s pupil plane. When half of the pupil plane is blocked by the SLM, a phase gradient image forms on the image plane. Using two such phase gradient images captured separately by applying complementary half-circle pupils on SLM, a DPC image can be constructed that carries the sample’s phase information. A quantitative phase image of the sample can be reconstructed after a deconvolution procedure. Further, we are able to combine this quantitative phase with the sample’s intensity image to obtain the complete complex object field which then allows us to post-process the image. We report experimentally that aberrations arising from the optical elements in the system can be corrected by deconvolving the reconstructed image with a pre-calibrated pupil function. We can also digitally extend the depth of field using angular spectrum propagation algorithm. With our PMDPC imaging setup where NA equals to 0.36, a quantitative phase image with periodic resolution of 1.73µm is obtained. The depth of field for a 20x, 0.4NA objective is extended digitally by 20 times to -50~50 micrometers.

Paper Details

Date Published: 24 April 2017
PDF: 1 pages
Proc. SPIE 10074, Quantitative Phase Imaging III, 100740P (24 April 2017); doi: 10.1117/12.2252576
Show Author Affiliations
Hangwen Lu, California Institute of Technology (United States)
Jaebum Chung, California Institute of Technology (United States)
Xiaoze Ou, California Institute of Technology (United States)
Changhuei Yang, California Institute of Technology (United States)

Published in SPIE Proceedings Vol. 10074:
Quantitative Phase Imaging III
Gabriel Popescu; YongKeun Park, Editor(s)

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