Rasouli Saifollah, Khazaei Ali Mohammad, Hebri Davud
J Opt Soc Am A Opt Image Sci Vis. 2018 Jan 1;35(1):55-64. doi: 10.1364/JOSAA.35.000055.
We experimentally demonstrate and theoretically predict a new and unprecedented optical carpet that includes all the geometric shadow and far-field and near-field diffraction patterns at the transverse plane in the diffraction from a radial grating illuminated by a plane wavefront. The main feature of using radial grating is the continuous change of the spatial period along the radial direction. Therefore, the geometric shadow, and the near-field and far-field diffraction regimes are mixed at various propagation distances, and the traditional definitions for the different diffraction regimes would not apply here. We show that for a given propagation distance, at a certain radial distance the shadow regime changes to the near-field regime and at another certain radial distance, the diffraction pattern changes from a near-field to a far-field case.
我们通过实验证明并从理论上预测了一种全新且前所未有的光学地毯，它包含了平面波前照射径向光栅衍射时横向平面上的所有几何阴影以及远场和近场衍射图案。使用径向光栅的主要特点是空间周期沿径向方向连续变化。因此，几何阴影以及近场和远场衍射区域在不同传播距离处混合在一起，传统的不同衍射区域定义在此处并不适用。我们表明，对于给定的传播距离，在某个径向距离处阴影区域会转变为近场区域，而在另一个特定径向距离处，衍射图案会从近场情况转变为远场情况。
