A new approach for measurement of wire diameter by optical diffraction

A new approach for measurement of wire diameter lying in the range of 200 to 450 mu is proposed and demonstrated. The approach is based on evaluation of phase-correlation based similarity measure for two identical order fringes of a Z diffraction pattern. Diameter of wires is estimated by determining separation between identical order fringes. Robustness C Z' of the approach to noise is enhanced by using Gaussian and singular value decomposition based filtering. Implementation of the method with an off-the-shelf digital photo camera for acquiring experimental data from steel wires and thin slits C have dernonstrated an accuracy far better than 0.5% of dimension.