Speaker: Dr. Guoan Zheng
Affiliation: University of Connecticut
Abstract: Fourier ptychography is a recently developed phase retrieval approach for large field-of-view and high-resolution imaging. This technique stitches together many variably illuminated, low-resolution measurements in the Fourier space to expand the frequency passband and recover the high-resolution complex object image. Without involving any mechanical scanning, it facilitates large field of view imaging in a simple and robust manner. In this talk, I will first discuss the principle of phase retrieval. I will then introduce the Fourier ptychography approach and discuss its applications in microscopy and long-range imaging. I will also discuss how to model the Fourier ptychographic imaging process using a neural network and recover the complex object information using a popular machine learning library, TensorFlow. In the proposed neural network, the object is treated as 2D learnable weights of a convolutional or a multiplication layer. The output of the network is modeled as the loss function one aims to minimize. The batch size of the network corresponds to the number of captured low-resolution images in one forward / backward pass. Since convolution and multiplication are the two most-common operations in imaging modeling, the model may provide a new perspective to examine many coherent and incoherent systems.
Biography: Dr. Guoan Zheng received the M.S. and Ph.D. degrees in electrical engineering from Caltech in 2008 and 2013, respectively. He is currently an assistant professor at the University of Connecticut, with a joint appointment in Biomedical Engineering and Electrical Engineering departments. He is the recipient of UConn research excellence award, Caltech Demetriades Thesis Prize, and Lemelson-MIT Caltech Student Prize. The Fourier ptychography approach he developed is now a subchapter in Goodman’s famous textbook, “Introduction to Fourier Optics.” His current research interest focuses on the development of novel imaging and sensing techniques for biomedical applications.
Date(s) - Apr 11, 2018
1:00 pm - 2:30 pm
E-IV Maxwell Room #57-124
420 Westwood Plaza - 5th Flr. , Los Angeles CA 90095