Phased Array Imaging in Partially Coherent Light

Period of Performance: 08/12/1987 - 08/12/1989

$417K

Phase 2 SBIR

Recipient Firm

Statcon, Inc.
2208 COUNTRYSIDE DR.
Silver Spring, MD 20904
Principal Investigator

Abstract

WE SHALL PERFORM NUMERICAL CALCULATIONS, VALID FOR ZENITH AND OFF-ZENITH VIEWING, TO ASSESS THE EFFECT OF ATMOSPHERIC TURBULENCE ON THE INTENSITY CORRELATION IMAGING PROCEDURE. FIRST, WE SHALL CALCULATE THE TWO-POINT INTENSITY CORRELATION FUNCTION WITH THE SPATIAL SPECTRUM AS AN INTERMEDIATE STEP. THESE CALCULATIONS ASSUME ISOPLANICITY. SUBSEQUENTLY, WE SHALL CALCULATE THE FIRST-ORDER CORRECTION RESULTING FROM NONISOPLANICITY. NEXT, WE SHALL ANALYZE THE EFFECT OF ATMOSPHERIC TURBULENCE ON MEASUREMENTS OF THE TRIPLE CORRELATION FUNCTION. WE SHALL DERIVE A GENERAL FORMULATION WHICH INCLUDES NONISOPLANATIC EFFECTS. WE SHALL FIND PERTURBATION EXPRESSIONS FOR THE ISOPLANATIC CASE AND THE FIRST-ORDER ISOPLANATIC CORRECTION CONDITIONS. WE SHALL ALSO MAKE TWO-DIMENSIONAL CALCULATIONS TO QUALITATIVELY DETERMINE THE EFFECT OF STRONG TURBULENCE. WE PROPOSE TO CONDUCT A LABORATORY EXPERIMENT INVOLVING PROPAGATION OF LIGHT THROUGH TURBULENCE GENERATED IN A HEATED WATER TANK. SUCH AN EXPERIMENT CAN INCLUDE ALL THE IMPORTANT EFFECTS PRESENT IN A FIELD EXPERIMENT. WE SHALL BE ABLE TO MEASURE THE INDEX-OF-REFRACTION FLUCTUATIONS OF THE TURBULENCE SIMULTANEOUSLY WITH THE INTENSITY CORRELATION MEASUREMENTS. THIS WILL ALLOW AN UNAMBIGUOUS CHECK OF THE THEORY AND NUMERICAL SIMULATIONS AND ALLOW US TO SEE THE EFFECT OF APERTURE AVERAGING AND VARIOUS ARRAY CONFIGURATIONS UNDER IDENTICAL TURBULENCE CONDITIONS.