Crossed grating 3 x 3 beam lateral shear interferometry for extended range wave front sensing is presented. A Fresnel diffraction pattern of two multiplicatively superimposed linear diffraction gratings each generating three diffraction orders is recorded. A simple solution employs a common crossed binary amplitude Ronchi grating with spatial filtering. Digital processing of a single-shot pattern includes separating multidirectional pairs of orthogonal lateral shear interferograms, retrieving second harmonics of their intensity distribution, and calculating shearing phases. Single-frame automatic fringe pattern processing based on the Hilbert-Huang transformis used for this purpose. Using second harmonics extends the aberration measurement range since they encode self-imaging free two-beam interferograms without contrast modulations. Experimental works corroborate the principle and capabilities of the proposed approach. (C) 2016 Optical Society of America
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机译：提出了用于扩展范围波前感测的交叉光栅3 x 3光束横向剪切干涉仪。记录分别产生三个衍射级的两个乘法叠加线性衍射光栅的菲涅耳衍射图案。一个简单的解决方案是使用具有空间滤波功能的通用交叉二进制振幅Ronchi光栅。单脉冲模式的数字处理包括分离正交横向剪切干涉图的多方向对，获取强度分布的二次谐波以及计算剪切相位。为此，使用了基于Hilbert-Huang变换的单帧自动条纹图案处理。使用二次谐波扩展了像差测量范围，因为它们对无对比度调制的自成像免费两光束干涉图进行了编码。实验工作证实了该方法的原理和功能。 （C）2016美国眼镜学会
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