中国物理B ›› 1999, Vol. 8 ›› Issue (2): 81-88.doi: 10.1088/1004-423X/8/2/001
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盛正卯, 杨焕雄
Sheng Zheng-mao (盛正卯), Yang Huan-xiong (杨焕雄)
摘要: An generalized version of the Siegman formula which comes directly from Helmholtz equation is reported in this paper. Based on this formula, a comparison between the two definitions of the light beam far-field divergence angle is made. It is discovered the Siegman's moment definition for divergence angle would not make sense if the light beam could not be approximated to the slowly varying one. The proof of inequality M2≥1 given by Chen and Qiu would fail if the evanescence wave effects are considered.
中图分类号: (Beam characteristics: profile, intensity, and power; spatial pattern formation)