The astigmatism from a plane grating placed in the divergentlight beam was used to compensate the astigmatism from an objective lens.
将平面光栅置于发散光中,利用平面光栅产生的像散来补偿物镜产生的像散。
2
The advantages are that defects light are not divergent and just transforming mask can fabricate different types of photonic lattice. The disadvantages are complexity of device, not easy to adjust.