Patents
The apparatus of the invention measures sieve dimensions by non-contact optical method which consists of image grabbing, converting the grabbed analog optical image to digital electronic image, effecting image analysis of the digital electronic signal using wavelet transform, which constitutes decomposing, separating, resolving and decimating the electronic signal into separated warp (horizontal) and weft (vertical) components and reconstructing the resolved, decimated and separated components of warp and weft, respectively, to obtain reconstructed digital images of warp and weft separately. The separated images of warp (horizontal) and weft (vertical) components allows concurrent measurement of sieve dimensions, such as measuring the diameter of wires, spacing between wires and detecting flaws in a sieve. The apparatus is capable of measuring sieve parameters in a single optical exposure of areas up to 100 cm of circular or square geometry. The diameter and spacing of the wire in the sieves can be measured with an accuracy of the order of 1µm and uncertainty of measurement of ± 2µm at 95% confidence level. The apparatus is also found suitable for detecting any missing wire or any other defect like bending or kink in the wire. This apparatus provides fast and accurate results with ease, in comparison with the existing methods.