DISPERSION CONTROL USING CHIRPED MIRRORS IN FEMTOSECOND LASER SYSTEM FOR OPHTHALMIC APPLICATION

A femtosecond laser system for ophthalmic applications, which employs a number of chirped mirrors in the laser beam delivery system between the laser head and the objective lens. The chirped mirrors perform the dual function of both turning the laser beam in desired directions and compensating for beam broadening due to group delay dispersion (GDD) of the optical elements of the system. Each chirped mirror reflects the laser beam only once. Four chirped mirrors are used, each providing up to -5000 fs2 of negative GDD per bounce, to provide a total of -18,000 fs2 negative GDD to compensate for the positive GDD of +18,000 fs2 introduced by other optical elements in the laser beam delivery system. This eliminates the need for a pulse compressor that would employ a grating pair, prism pair or grism pair, and therefore significantly reduces the size of the system and the alignment requirements.