title: Two-photon Shack-Hartmann wavefront sensor.
abstract: We introduce a simple wavefront sensing scheme for aberration measurement of pulsed laser beams in near-infrared wavelengths (<2200  nm), where detectors are not always available or are very expensive. The method is based on two-photon absorption in a silicon detector array for longer wavelengths detection. We demonstrate the simplicity of such implementations with a commercially available Shack-Hartmann wavefront sensor and discuss the detection sensitivity of this method.
authors.forename: Fei
authors.initials: F
authors.lastname: Xia
authors.forename: David
authors.initials: D
authors.lastname: Sinefeld
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Chris
authors.initials: C
authors.lastname: Xu