Point-spread function reconstruction in high aperture lenses focusing ultra-short laser pulses

In this paper we discuss the measurement of the amplitude point-spread function (PSF) of high aperture lenses focusing ultrashort laser pulses. In the experimental set-up a Twyman-Green interferometer and an autocorrelator are combined to function as a phase-shifting interferometer which is then used to measure the phase distribution in the pupil plane of the lens. Numerical reconstruction of the interferograms permits us to calculate the spatial distribution of the amplitude and phase of the point-spread function. Our work is relevant for cases when ultra-short laser pulses are focused for applications such as two- and three-photon fluorescence, second- and third-harmonic generation microscopy, optical coherence tomography and microscopy, and optical data storage.