[1] R. Li, Y. Wang, C. Tang, Y. Wang, H. Shang, N. Chi. Chin. Opt. Lett., 11, 080605(2013).

[2] H. Dong, H. Zhang, K. Lang, B. Yu, M. Yao. Chin. Opt. Lett., 12, 052301(2014).

[3] E. F. Schubert, J. K. Kim. Science, 308, 1274(2005).

[4] L. A. Caffarelli, V. I. Oliker. Weak solutions of one inverse problem in geometric optics(1994).

[5] X. Wang. Inverse Problem, 12, 351(1996).

[6] L. A. Caffarelli, S. A. Kochengin, V. I. Oliker. Contemp. Math., 226, 13(1999).

[7] T. Glimm, V. Oliker. J. Math. Sci., 117, 4096(2003).

[8] X. Wang. Calc. Var., 20, 329(2004).

[9] C. Canavesi, W. J. Cassarly, J. P. Rolland. Opt. Lett., 37, 3852(2012).

[10] C. Canavesi, W. J. Cassarly, J. P. Rolland. Opt. Eng., 53, 31306(2014).

[11] C. Canavesi, W. J. Cassarly, J. P. Rolland. Opt. Lett., 38, 5012(2013).

[12] W. B. Elmer. The Optical Design of Reflectors(1980).