Mechanical method to reduce aberrations for a two-sided coating axisymmetric optical lens based on the specialized finite element method.

Two-sided coated optical lenses are important in optical applications. A film-stress-induced aberration can adversely affect the lens performance. In this paper, a mechanical method has been developed to reduce this aberration. The proposed method uses a specialized finite element method with an easy modeling process and high versatility to analyze the impact of film parameters (including stress, the thickness, and the coating range) on aberrations under different lens geometric parameters. Theoretically, by selecting the property film parameters within the range of an application's requirements can reduce the aberrations. The proposed method could reduce film-stress-induced aberrations to make the aberration compensation easier.

A distribution-based selective optimization method for eliminating periodic defects in harmonic signals.

Due to environmental interference and defects in measured objects, measurement signals are frequently affected by unpredictable noise and periodic defects. Moreover, there is a lack of effective methods for accurately distinguishing defect components from measurement signals. In this study, a distribution-based selective optimisation method (SOM) is proposed to mitigate the effects of noise and defect components. The SOM can be seen as a binary- or multiple-class signal classifier based on an error distribution, which can simultaneously eliminate periodic defect components of measurement signals and proceed with signal-fitting regression. The effectiveness, accuracy, and feasibility of the SOM are verified in theoretical and realworld measurement settings. Based on theoretical simulations under various parameter conditions, some criteria for selecting operation variables among a selection of parameter conditions are explained in detail. The proposed method is capable of separating defect components from measurement signals while also achieving a satisfactory fitting curve for the measurement signals. The proposed SOM has broad application prospects in signal processing and defect detection for mechanical measurements, electronic filtering, instrumentation, part maintenance, and other fields.