California Institute of Technology
Department of Electrical Engineering
Biophotonics Laboratory

roarke (at) caltech (dot) edu

Short Biography

I am a recent PhD graduate from Caltech’s electrical engineering department. I mostly work with optics and algorithms. Please check out some of my papers in the "Publications" section linked above.

Prior to coming to Caltech I was a graduate student at MIT. I also had a bit of time to help create a job recommendation algorithm, Beansprock (see press here and here).

October 2015 news: I just graduated with my PhD!

Over the past 6 months, I've mostly been working on a way to extend our Fourier ptychographic method to operate in 3D. Now, we can use a regular microscope and an LED array to capture the full volume of a thick biological specimen:

Diffraction tomography with Fourier ptychography
R. Horstmeyer and C. Yang, pre-print via Arxiv (2015).

September 2015 news: Three new papers

The first two papers below are about some tricks we use to control the behavior of light, deep within tissue, to image very small things (like cells). The third paper is an improved algorithm to reconstruct ptychographic images.

Guidestar-assisted wavefront shaping methods for focusing light into biological tissue
R. Horstmeyer, H. Ruan and C. Yang, Nature Photonics 9, 563-571 (2015)

Translation correlations in anisotropically scattering media
B. Judkewitz*, R. Horstmeyer*, I. M. Vellekoop, I. N. Papadopoulos and C. Yang, Nature Physics 11, 684-689 (2015) (*shared 1st authorship, and its the cover article!)
Related news: Nature news and views

Solving ptychography with a convex relaxation
R. Horstmeyer, R. Y. Chen, X. Ou, B. Ames, J. A. Tropp and C. Yang, New Journal of Physics 15, 053044 (2015).

Videos of my research

If you're more into watching clips (instead of reading academic papers), then you might like to learn more about my research through some videos.

First, I recently had the honor of giving an Everhart Lecture at Caltech. In this talk, I summarize my lab's work creating microscopes that capture gigapixel-scale images. You can find more information about this lecture here, or watch it for free at iTunes U at the link below:

Computational microscopy: turning megapixels into gigapixels

Second, I was lucky enough to feature some of my research on cryptography on the Science Channel show, Through the Wormhole, with Morgan Freeman. Check out my explanation of how one-time pads and physical unclonable functions work!

The third video you might like is a great educational tutorial on how a camera works, created by Stephanie Li Xian Seo and her team for young and curious students at If anyone else would like to animate any other optics-related subjects, please let me know!