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  • Neuroscience Seminar Series:

    Changhuei Yang – Professor of Electrical Engineering,
    Bioengineering and Medical Engineering California Institute of Technology

    ‘Focusing light into biological tissues with wavefront shaping’

    Captation et conception vidéo: Service audiovisuel de Paris Descartes.

    video25-75927Video sur Média2Descartes.

    I will discuss two lines of wavefront engineering work going on in my group.
    Time-Reversal Optical Focusing – We appear opaque because our tissues scatter light very strongly. Traditionally, focusing of light in biological tissues is confounded by the extreme scattering nature of tissues. Interestingly, optical scattering is time-symmetric and we can exploit optical phase conjugation methods to null out scattering effects. I will discuss our recent results in using different types of guidestar methods in combination with digital optical phase conjugation to tightly focus light deep within biological tissues. These technologies can potentially enable incisionless laser surgery, targeted optogenetic activation, high-resolution biochemical tissue imaging and more.
    Fourier Ptychography – Microscopes are complex and fussy creatures that are capable of delivering limited image information. This is because physical optical lenses are intrinsically imperfect. The perfect lenses we draw in high school ray diagrams simply do not exist. I will discuss our recent work on Fourier Ptychographic Microscopy – a computational microscopy method that enables a standard microscope to push past its physical optical limitations to provide gigapixel imaging ability.