Particle and flow field measurements by laser holographyHolograms make transmission recordings of aerodynamic events which are real-illuminated with ground-glass light diffusers and with no requirements for precision. The three-dimensional interferograms can be recorded by stored-beam, double-exposure, and double-plate techniques. Weak traveling shock waves, generated by rotating blade rows of an aircraft fan compressor, can be visualized by rapid double-exposure holograms recorded with a ruby laser. The same laser technique can also determine flow velocities from holograms of small flow-entrained particles. Particles larger than one-quarter millimeter are recorded under rear diffuse illumination conditions. Smaller particles can be recorded by their own forward scattering of laser light through the sensitivity of the holographic process for weak signals. Since the holographic apparatus can be path-matched, both particle and flow interferograms can be recorded with lasers of short coherence length.
Document ID
19770037747
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Wuerker, R. F.
Date Acquired
August 9, 2013
Publication Date
January 1, 1976
Subject Category
Instrumentation And Photography
Meeting Information
Meeting: Conference on The engineering uses of coherent optics