Optical EngineeringAmplitude filter and Fourier-based modal method for quality control of microlenses array
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We present a computer simulation and an experimental realization of an optical setup for automatic quality control of microlenses arrays. The method is based on a 4f correlator setup with an amplitude filter. The output intensity signal is simple to analyze and interpret because the intensity is proportional to the first derivative of the distortion of the input wavefront. This method is shift invariant, allows for the examination of single elements, or sets of micro-optical elements simultaneously, and is particularly suitable for assessing the quality of optical elements. However, combining the method with a more detailed analysis based on the Fourier modal method, allows for obtaining quantitative data. Although errors are within the 2-3% range, such an analysis enables a fast and relatively accurate comparison of numerous elements with each other and with the model. The combination has never been applied but allows for a fast and cost-effective analysis that can be used for industrial purposes. Both the methods give separate results for each lens or for all the lenses in the array, simultaneously. In the combination proposed, the analysis is computer-based and done on the basis of the initial single optical measurement.