Development of an Infrared Schlieren System.
Abstract
The research covers several aspects of gas- and flow-visualization with infrared imagery. The purpose of the research was to show that infrared analogues of standard optical methods are suitable for visualizing flow fields containing molecular gases. The infrared refractive index n of molecular gases was measured at CO2 laser frequencies. The variation of n near absorption lines forms a basis for species-selective schlieren (and other optical methods) having enhanced sensitivity to density gradients. Following preliminary tests using a x-y IR detector scanner schlieren, we developed a new method of IR photography using conventional and Polaroid films designed for use with visible light. The result was a patented process suitable for photographic IR laser patterns and other images having power densities >/100 mw/sq. cm in the wavelength range 5-10 micrometers. The method was applied to contract work on IR optics, principally to bi-prism measurements of gaseous refractive index. For comparison, high resolution interferometric measurements were made on the refractive index of air, nitrogen, ethylene and ozone at lines in the 9.6 and 10.6 micrometers CO2 laser bands.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1978
- Accession Number
- ADA062032
Entities
People
- Gene F. Frazier
- J. M. Lindsay
- T. D. Wilkerson