A LASER DOPPLER VELOCIMETER WITH RANGE AND DIRECTIONAL GRATING CAPABILITIES

CURRENT METHODS FOR PREDICTING THE EFFECTS OF WIND ON PROJECTILE TRAJECTORIES ARE LIMITED, BECAUSE THESE METHODS ASSUME A HOMOGENEOUS WIND VECTOR. ACTUAL WIND PATTERNS ARE INHOMOGENEOUS IN TERMS OF BOTH DIRECTION AND RANGE. TO SOLVE THESE PROBLEMS, PHYSICAL OPTICS CORPORATION (POC) PROPOSES A NOVEL LDV DESIGN, BASED ON A COMBINATION OF POC'S UNIQUE MULTIPLEXED HOLOGRAPHIC OPTICAL ELEMENTS (HOES) AND CONFOCAL IMAGING/FOCUSING OPTICS. THE UNIQUE ADVANTAGE OF POC'S APPROACH IS THAT IT CAN MEASURE THE ENTIRE 3D WIND VELOCITY WHILE SIMULTANEOUSLY PERFORMING MEASUREMENTS IN MANY DIRECTIONS AND RANGES. POC'S PROPOSED DEVICE REPRESENTS BOTH A RANGE AND DIRECTIONAL GATED LDV THAT PROVIDES A SAMPLED PROFILE OF THE 3-D COMPONENTS OF WIND VELOCITY ALONG THE BEAM PATH, SO THAT RELATIVE TARGET VELOCITY WITH RESPECT TO PLATFORM CAN BE MEASURED. THE READ-OUT SUBSYSTEM GIVES REAL-TIME OUTPUT SUITABLE FOR CALCULATING PERTURBATIONS ON PROJECTILE TRAJECTORIES. SYSTEM RANGE CAN BE AT LEAST 2.5 KM, AND THE OPTICAL SUBSYSTEM IS COMPACT AND EFFICIENT. THE SUCCESS OF THIS RESEARCH WILL INTRODUCE NEW CAPABILITIES IN LDVS FOR WIND VELOCITY VECTOR MEASUREMENTS AT MULTIPLE RANGES AND WILL ALSO FIND APPLICATIONS IN FLUID MECHANICS RESEARCH, MEASUREMENT OF SUPERSONIC VELOCITIES, LASER DOPPLER ANEMOMETERS AND MANY OTHER SENSING AND PROBING APPLICATIONS.