Open AccessMeasurement of nonlinear index by a relay-imaged top-hat Z-scan technique
Author(s) -
T Shimada,
N. A. Kurnit,
Mansoor SheikBahae
Publication year - 1996
Language(s) - English
Resource type - Reports
DOI - 10.2172/212526
Subject(s) - optics , aperture (computer memory) , lens (geology) , national ignition facility , sensitivity (control systems) , beam (structure) , diffraction , sample (material) , image quality , gaussian , physics , spurious relationship , image (mathematics) , computer science , engineering , electronic engineering , artificial intelligence , acoustics , laser , inertial confinement fusion , machine learning , thermodynamics , quantum mechanics
Measurements of the nonlinear index of a number of optical materials of interest for the National Ignition Facility have been performed at 1,064 nm and 355 nm by a modified version of the ``top-hat`` technique and the results compared with the more standard gaussian-beam Z-scan technique. The top-hat technique has the advantages of higher sensitivity and smaller uncertainties introduced by beam-quality considerations. The authors have made what they feel to be an additional improvement by placing the defining aperture for the top hat at the front focal plane of the lens that focuses the beam into the sample and then reimaging the input aperture with a second lens onto a ccd camera. Reimaging eliminates diffraction fringes and provides a stationary image even for a wedged sample; recording the entire image permits minimization of spurious effects such as varying interference fringes