Early detection of material damage is critical when monitoring aircraft, bridges, and other infrastructure, and it is often very desirable that the detection be nondestructive, such that the incipient damage can be detected while keeping these structures intact and protected from further damage.  Ultrasound is a nondestructive material evaluation technique, and using lasers to generate ultrasound gives high frequency information allowing for detection of very small features in the material that might be overlooked when using other ultrasonic techniques such as contacting transducers. Our research involves using laser ultrasonics to detect changes in the material's microstructure due to fatigue damage well before microcrack formation. Aluminum alloys relevant to the aircraft industry are fatigued using standard methods and inspected using a pulsed Nd:YAG 1064nm laser for ultrasonic generation and a Michelson-type interferometer to measure surface displacement. This type of arrangement allows us to simultaneously detect the stiffness and attenuation of longitudinal and shear waves in a single measurement.  Currently, we are manipulating the laser beam into generating polarized shear waves so that we can detect changes in material stiffness due to the inherent anisotropy in processed metals, and measure the effects fatigue damage has on this material anisotropy.