Scattering by a narrow rectangular gap

It has become important to investigate the scattering effect from the local structures of objects. This is due to the fact that such local structures may behave as the local guiding or resonance constituents, and sometimes excite the internal resonances. This characteristic may be utilized for the identification and the detection of cracks and gaps, and for optimal design of optical disk pits. Therefore, the scattering analyses for this configuration have been done by many authors. Plane wave scattering by a narrow rectangular gap has been analyzed by utilizing the Kobayashi and Nomura´s (1978) method. After formulation is done in a rigorous manner, a simple formula to estimate the scattering field has been obtained for the narrow case. Numerical calculations have been done to check the validity of the derived formulas for various gap width and depth.