Wei Li, Baiquan Tang, Xinzheng Zhang, Feng Gao, Longchang Liu, Qiang Wu, Leiting Pan, Cibo Lou, Shangyu Guo, Romano A. Rupp, Jingjun Xu. Investigation on the phase shifts of extinction and phase gratings in polymethyl methacrylate[J]. Chinese Optics Letters, 2010, 8(1): 18