New generation high-energy tunable femtosecond laser for nonlinear optical microscopes to investigate advanced imaging of ophthalmic tissue

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Recent innovations in laser technology have resulted in a remarkable advancement in the generation and application of ultrashort laser pulses. Femtosecond lasers are now used by scientists to "watch" a molecule fall apart as it undergoes a chemical reaction, and by surgeons to perform laser surgery with unprecedented precision. Ultrafast laser technology is still advancing at a rapid rate, and ultimately short pulses may soon be used to perform laser eye surgery with sub-micron precision. Our long-term goal is to increase our capability to image the eye, for improved quality of eye health of Canadians. To achieve this goal, one technological challenge is to be able to clearly image the extremely small "cuts" produced by the femtosecond laser. This requires real-time three-dimensional imaging of structures within the eye with sub-micron spatial resolution. We propose here to simultaneously use multiple (multi-modality) nonlinear optical microscopy methods, to obtain more comprehensive information of the sample. One important method, named epidetected Coherent Anti-Stokes Raman Scattering (e-CARS) microscopy, is an ideal method to realize such ultimate imaging. e-CARS microscopy provides a unique approach to imaging biological samples by using molecular vibrations as a contrast mechanism. e-CARS microscopy is capable of three-dimensional imaging of minute structures with sub-micron resolution, and can be easily implemented into laser surgical systems, since the same optics used in laser surgery can be used for e-CARS microscopy. Thus, in vivo e-CARS microscopy will greatly contribute to the enhanced precision of femtosecond laser eye surgery. Another potentially important application is the diagnosis and follow-up of age-related macular degeneration (AMD). This retinal disease is the leading cause of legal blindness in Canada. Approximately 25% of Canadians over 75 years of age are affected to some level. The development and application of e-CARS microscopy will contribute to the better understanding of the pathophysiology of this disease, and will help to find a cure for AMD.