[2] Raymond J. Beach, William J. Benett. Lensing duct [P]. US005307430A, United States Patent. 1994
[3] Raymond J. Beach. Theory and optimization of lens ducts[J]. Appl. Opt., 1995, 35(12):2005~2015
[4] Raymond J. Beach. Hollow lensing duct [P]. US006160934A, United States Patent. 2000
[5] E. C. Honea, R. J. Beach, S. C. Mitchell et al.. High-power dual-rod Yb∶YAG laser[J]. Opt. Lett., 2000, 25(11):805~807