title: Rapid, in-line, non-interferometric auto- and cross-correlator for microscopy.
abstract: We demonstrate a simple, in-line scheme for determining the duration of ultrafast pulses in the focal region of a high-numerical-aperture microscope objective. Photocurrent generated in a GaAsP photodiode by two-photon absorption of orthogonally-polarized laser beams that meet at a slight angle is used to autocorrelate lasers non-interferometrically. Cross-correlation between two lasers is also demonstrated. This setup, which can be built readily by a microscope user who is not an optics expert, allows for the rapid characterization of pulses that can be hundreds of fs long while making it possible for all of the laser intensity to be employed for nonlinear optical microscopy after the pulse duration has been measured.
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Lafratta
authors.forename: Linjie
authors.initials: L
authors.lastname: Li
authors.forename: John T
authors.initials: JT
authors.lastname: Fourkas