Product Code: JLA_3_1_27

Authors:
Stephen E. Dunagan
National Full‐Scale Aerodynamics Complex, NASA‐Ames Research Center, Moffett Field, California, 94035 U.S.A.

A procedure is identified for adapting Schmidt‐Cassegrain telescope optics to perform the laser beam focusing and scattered light collection tasks associated with dual‐beam laser Doppler velocimetry. A generic, aperture‐normalized system is analyzed using ray‐tracing and Gaussian beam propagation analysis methods. Two relatively simple modification approaches are identified, each of which provides probe volume imaging performance near the diffraction limit. Similar modifications may be configured for laser beam focusing and provide small, high‐intensity beam waists near the paraxial focus. The predicted performance of the generic modified telescope system exceeds that of similar large‐aperture lens designs. Performance parameters including resolution limit and beam waist size and location were confirmed experimentally.