title: Wavefront measurements of a laser-induced breakdown spark in still air.
abstract: Experimental measurements of the wavefronts of the light from a laser-induced breakdown (LIB) spark in non-moving air are presented and compared to spark dimensional data acquired from photographic measurements of the spark. The data show that the variation in the spark emitted wavefront between ignitions can be directly related to the motion of the spark volumetric centroid. The dominant modal components of the emitted wavefront variations are presented, as well as quantitative results for the magnitude of the wavefront variations. The results are relevant to the use of LIB as a light source for the measurement of optical aberrations such as those caused by compressible (i.e., "aero-optic") flows around an aircraft in flight, and data are shown indicating that LIB could be successfully used to measure the aberrating effect of compressible shear layers and boundary layers at typical cruise Mach numbers.
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA. rrennie@nd.edu
authors.forename: R Mark
authors.initials: RM
authors.lastname: Rennie
authors.forename: David
authors.initials: D
authors.lastname: Goorskey
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Whiteley
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Jumper