Focusing of sub 10 fs laser pulses with microscope objectives

Summary form only given. Tight focusing of femtosecond pulses is important for a variety of applications such as nonlinear microscopy. Spectral interferometry was applied to study the two chromatic aberration effects of a 100X/0.85 (Zeiss) microscope objective. A maximum delay of about 23 fs between pulses propagating along the optic axis and along the marginal rays is obtained. The spectral interferogram also yielded information on the second and third order (radius independent) group delay dispersion. These data were used to optimize a prism sequence third-order-dispersion mirror combination to pre-chirp the 9.2 fs pulses from a mode locked Ti:sapphire laser.