Einstein Postdoctoral Fellow
Charitè Medical School
Humboldt University of Berlin
Bioimaging and Neurophotonics Laboratory

roarke (at) charite (dot) de

Short Biography

I am a recent PhD graduate from Caltech’s electrical engineering department, and am currently an Einstein postdoctoral fellow with the Judkewitz lab at Charitè Medical School in Berlin. I mostly work with optics and algorithms. Please check out some of my papers in the "Publications" section linked above.

March 2017: My new Duke website

While I'll try my best to keep this page updated as well, I now have a new website for the Computational Optics Lab that I am starting at Duke University:


Please be sure to check out this new site for updates about me and my research!

February 2017: Einstein Foundation article and video

The Einstein Foundation Berlin just wroteup a short piece about me and my research. They also made a video about some of my work at the intersection of optics and neuroscience.

February 2017: New paper about on-chip holographic video

We have a new method that can take really fast videos of small micro-organisms that swim around on top of a sensor. It is based on a modified phase retrieval algorithm, which you can read about more here:

Subsampled phase retrieval for temporal resolution enhancement in lensless on-chip holographic video
D. Ryu, Z. Wang, K. He, G. Zheng, R. Horstmeyer and O. Cossairt, Biomedical Optics Express 8, 1981-1995 (2017).

June 2016: Eventually heading back to to Duke!

I will join Duke University's Biomedical Engineering Department as an assistant professor in 2018, after finishing my postdoctoral fellowship in Berlin. If you hope to start graduate school or a postdoc in a couple of years and find my work interesting, please feel free to get in touch!

May 2016: Awarded Charles Wiltz prize at Caltech

I was awarded this prize from Caltech for "outstanding research in electrical engineering towards a PhD", which you can read more about here.

February 2016: New paper about microscope resolution

Characterizing the resolution of a microscope can be a little bit tricky. In the following paper, we outline a set of guidelines and propose a common resolution standard for a particular class of microscopes that image with coherent light:

Standardizing the resolution claims for coherent microscopy
R. Horstmeyer, R. Heintzmann, G. Popescu, L. Waller and C. Yang, Nature Photonics 9, 68-71 (2016).

November 2015: 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, Optica 8, 827-835 (2016).

September 2015: 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 scienceqanda.com. If anyone else would like to animate any other optics-related subjects, please let me know!