Liquid Crystal-based Underwater Imager

"The direct conversion of acoustical images into visible images has been accomplished by ETC and others. Acoustic images formed at the back focal plane of an acoustic lens were directly converted and photographed. This method has the potential of allowinginexpensive hand held imagers for divers in littoral waters. The Phase I work laid the foundation for measuring properties of liquid crystal (LC) materials, which are fundamentally important to acoustic imaging. Chief among these was measurement of theacoustic anisotropy. Also important were sensitivity, dynamic range, speed of response, and operational temperature. All the necessary tests and analyses regarding acoustic lenses and general materials were developed during the Phase I for designing animager. Phase II work involves investigations of specially engineered LC materials with enhanced acoustic sensitivity and a new method of LC imaging. The new materials offer many enhancements unavailable in the LCs commonly used for displays. This newmethod of imaging offers a simple, but effective method with the possibility of greatly enhancing the dynamic range.BENEFITS: The benefit to the Navy is the production of a small, portable, and inexpensive acoustic imager for deployment in low visibility,littoral environments. The direct transformation of a sonar return to an intensity map at the back focal plane of a conventional lens eliminates a heavy computational burden from the