Our Research
We are interested in developing new optical imaging techniques that challenge the limitations of conventional microscopy systems, and such challenges usually lead us to explore the fundamental physics of image formation. There are three main projects ongoing in our small group: extended depth of field imaging, super-resolution microscopy, and quantitative differential interference contrast microscopy.
For extended depth of field imaging, we alter the wavefront at the pupil plane, such that the resultatnt point spread function elongates in the axial direction much longer than in a conventional imaging system. When used appropriately in conjunction with computational deblurring, the extended depth of field can image a thick volume with minimal loss of resolution and without changing focus.
As to super-resolution microscopy, our approach is fundamentally different from other existing techniques and is instrument-wise much simpler. We achieve super-resolution by focusing the laser beam for fluorescence excitation, and numerically decomposing the photo-emitters in each illuminated region. The results show that our method can improve the conventional imaging resolution by ~4-5 fold.
In quatitative differential interference contrast microscopy, we utilize the mathematical property of differential interferometry and reconstruct the original optical path map numerically. Such information can help biologists measure the thickness of transparent cells with nanometer precision.