High Sensitivity Shadow Moire Using Nonzero-Order Talbot Distance

摘要

High sensitivity shadow moire using non-zero order Talbot distances is proposed. A mathematical description for the contrast of shadow moire fringes produced by broad spectrum light is presented and its validity is corroborated experimentally. Using the nonzero order Talbot distances, the dynamic range is increased substantially and higher measurement sensitivity becomes practical, which has not been possible with the conventional shadow moire using the zero Talbot distance. Contour intervals in the range of 40 to 50 (mu)m per fringe are practical. The critical parameters controlling fringe contrast are discussed and optical configurations for optimum contrast are suggested.