title: Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source.
abstract: Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors' precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO₄ laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed.
authors.affiliation: Department of Physics, Osnabrueck University, Barbarastrasse 7, Osnabrueck 49076, Germany. jtschent@uni-osnabrueck.de.
authors.forename: Juliane
authors.initials: J
authors.lastname: Tschentscher
authors.affiliation: Department of Physics, Osnabrueck University, Barbarastrasse 7, Osnabrueck 49076, Germany. shochheim@uos.de.
authors.forename: Sven
authors.initials: S
authors.lastname: Hochheim
authors.affiliation: Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Bremen 28359, Germany. hauke.bruening@ifam.fraunhofer.de.
authors.forename: Hauke
authors.initials: H
authors.lastname: Brüning
authors.affiliation: Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Bremen 28359, Germany. kai.brune@ifam.fraunhofer.de.
authors.forename: Kai
authors.initials: K
authors.lastname: Brune
authors.affiliation: Caesar Research Center, Ludwig-Erhard-Allee 2, Bonn 53175, Germany. kay-michael.voit@caesar.de.
authors.forename: Kay-Michael
authors.initials: KM
authors.lastname: Voit
authors.affiliation: Department of Physics, Osnabrueck University, Barbarastrasse 7, Osnabrueck 49076, Germany. mirco.imlau@uni-osnabrueck.de.
authors.forename: Mirco
authors.initials: M
authors.lastname: Imlau
keywords: drag reduction; laser beam parameters; optical riblet sensor; riblet degradation; wave fronts and ray tracing