Measurement of group delay dispersion of high numerical aperture objective lenses using two-photon excited fluorescence

Abstract

We determined the group-delay dispersion (GDD) of five microscope objectives by measuring the second-order autocorrelation at the focal points of the objectives with two-photon excited fluorescence as the power square sensor. We found that typical microscope lens systems introduce significant GDD (2000–6500 fs²). The third-order dispersion determined for these objectives limits the minimum obtainable pulse width at the focal point of an objective to 20–30 fs if not compensated. No significant chromatic aberration or higher-order dispersion effects were found for any of the optical components measured within the wavelength range of 700–780 nm and for pulse widths greater than 50–60 fs.