Biophotonics Laboratory
California Institute of Technology

The research of the Biophotonics Laboratory, led by Professor Changhuei Yang, is focused on the development of novel tools that combine optics and microfluidics to tackle diagnostic and measurement problems in biology and medicine. The major techniques that are under development in the laboratory include Fourier Ptychographic microscopy, time-reversal optical focusing and parallel microscopy.

The Fourier Ptychographic microscope represents a new way of tackling high-throughput digital pathology by transforming a physical optical problem to a computational problem. Through this reduction, we can push the performance of standard microscopes beyond their physical limitations. The Fourier Ptychographic method also enables the implementation of compact parallel microscopy solutions with the use of compact and cheap optical arrays. Our time-reversal optical focusing research aims to tackle the extreme turbidity of biological tissues through the use of optical time-reversal methods. This work can potentially enable incisionless laser surgery, high-resolution and deep-penetrating biochemical tissue imaging, optogenetic activation and more.

Some of our major research projects are outlined in the column on the right. For more detailed information, please visit our research page.

News and Announcements

Three postdoctoral positions are available in the Biophotonics Lab here at the California Institute of Technology. We seek highly motivated candidates who wish to join an energetic and collaborative team working on challenging projects. Postdocs with expertise in one or more of these areas: OCT, wavefront shaping, Fourier Ptychography and machine learning are highly encouraged to apply. The ideal candidates will be excellent team players and communicators with a strong background in experimental optics and/or biomedical imaging. Please email Prof. Yang at ( directly.

Information about applying to the graduate programs here at Caltech can be found on the Graduate Office website. The deadlines for graduate applications for the Fall can be found on the following webpages:
Bioengineering Dept.
Electrical Engineering Dept.
Medical Engineering Dept.

Each year in early February, Professor Yang reviews graduate applications. ***For Fall 2018, he will recruite three students into his group. If you are interested in joining his group and have already submitted your completed application to the Caltech Graduate Office by the deadline listed on their website, please send him an email ( to let him know. He will NOT be answering any emails. Shortlisted candidates will be contacted by mid February for interviews.

Biophotonics Lab Location

The Biophotonics Lab, get directions, is located in the Moore Laboratory on the main Caltech campus.

Fourier Ptychographic Microscopy (FPM)
The Fourier ptychographic microscopy (FPM) is an imaging method which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field, high-resolution complex sample image. Read more...

Wide Field of View Microscopy We have developed a new microscopy design that can achieve wide field-of-view (FOV) imaging and yet possesses a resolution that is comparable to a conventional microscope. This technology is scalable and represents a cost-effective way to implement wide FOV microscopy systems. Read more...

Time-reversal Wavefront Engineering
Elastic optical scattering is a deterministic and time reversible process. By recording the phase and amplitude of the propagating scattered light field and reproducing a back propagating optical phase conjugate (OPC) field, the light can retrace its trajectory through the scattering medium and return the original input light field. Read more...