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Abstract

This thesis concerns the first ever development of a variable spacing diffraction grating device created with the use of elastomeric surface waves. A variable spacing grating has the ability to deflect a laser beam to a continuous range of angles, thus allowing to steer the beam. This is achieved by diffracting an obliquely incident laser beam from a surface on which a mechanical wave is propagating. Silicone rubber has an extremely low Young's modulus compared to non-elastomeric solids, and it can be easily cast. Using this material, surface waves can be created with low power, and such waves travel very slowly (~ 1 m/s) compared to conventional surface wave devices (-1000 m/s). Four different types of elastomeric surface wave devices were constructed to examine their suitability as variable spacing diffraction gratings. Two of these produced surface waves that were suitable to diffract a laser beam. The device which produced the biggest effect and most stable propagating surface wave a thin membrane of silicone rubber, supported on water. It is shown that the propagation speed of such waves is consistent with the White/Wenzel model, which predicts a dispersion relationship in terms of the membrane thickness, tension and modulus. Overall, this structure appears to be promising for controlled diffraction, as well as other applications.