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18 May 1998 Radially varying dispersion in high-numerical-aperture focusing
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Proceedings Volume 3255, Applications of Ultrashort-Pulse Lasers in Medicine and Biology; (1998)
Event: BiOS '98 International Biomedical Optics Symposium, 1998, San Jose, CA, United States
Over the last few years a number of microscopical techniques have been developed that take advantage of ultrashort optical pulses. All these techniques rely on temporal pulse integrity at the focal point of a high-numerical aperture (NA) focusing system. We have investigated the dispersion induced broadening for pulses on the optical axis, using the two-photon absorption autocorrelation (TPAA) technique. We demonstrate that the induced broadening can be pre- compensated for by a properly designed dispersion pre- compensation unit for pulses as short as 15 femtosecond. Another source of pulse broadening in high-NA focusing systems is due to radial variations in the dispersion over the pupil of the objective. This may cause differences in the group delay between on-axis and outer ray wave packets, as well as differences in the broadening of the wave packets themselves. In this paper we present experimental results on the measurement of these radial variations in the dispersion characteristics over the aperture of high-NA microscope objectives, using a slightly modified TPAA technique.
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Michiel Mueller, G. J. Brakenhoff, Ulrich Simon, and Jeffrey A. Squier "Radially varying dispersion in high-numerical-aperture focusing", Proc. SPIE 3255, Applications of Ultrashort-Pulse Lasers in Medicine and Biology, (18 May 1998);

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