Daniel Alina A Gorcea Bivolaru

US Patent:

20080043219, Feb 21, 2008

Filed:

Aug 1, 2006

Appl. No.:

11/461569

Inventors:

Daniel Bivolaru - Hampton VA, US
Paul M. Danehy - Newport News VA, US
Joseph W. Lee - Williamsburg VA, US

Assignee:

United States of America - the Administrator of the National Aeronautics and Space Administration - Washington DC

International Classification:

G01P 3/36

US Classification:

356 285, 356 28, 356342

Abstract:

A method and apparatus for performing simultaneous multi-point measurements of multiple velocity components in a gas flow is described. Pulses of laser light are directed to a measurement region of unseeded gas to produce Rayleigh or Mie scattered light in a plurality of directions. The Rayleigh or Mie scattered light is collected from multiple directions and combined in a single collimated light beam. The Rayleigh or Mie scattered light is then mixed together with a reference laser light before it is passed through a single planar Fabry-Perot interferometer for spectral analysis. At the output of the interferometer, a high-sensitivity CCD camera images the interference fringe pattern. This pattern contains the spectral and spatial information from both the Rayleigh scattered light and the reference laser light. Interferogram processing software extracts and analyzes spectral profiles to determine the velocity components of the gas flow at multiple points in the measurement region. The Rayleigh light rejected by the interferometer is recirculated to increase the accuracy and the applicability of the method for measurements at high temperatures without requiring an increase in the laser energy.