[1] [1] Veldkamp W B, Leger J R, Swanson G J. Overview of microoptics past, present and future. Proc. SPIE, 1991, 1544:287～299

[2] [2] Sixt O P, Stauffer J M, Mayer J M et al.. One-step 3D shaping using a grey-tone mask for optical and microelectronic applications. Microelectron. Engng., 1994, 23:449～454

[3] [3] Suleski T J, O’shea D C. Gray-scale masks for diffractive-optics fabrication: 1. Commercial slide imagers. Appl. Opt., 1995, 34(32):7507～7517

[4] [4] Reimer K, Quenzer H J, Hurss M et al.. Micro-optic fabrication using one-level gray-tone lithography. Proc. SPIE, 1997, 3008:279～288

[6] [6] Hopkins H H. On the diffraction theory of optical images. Proc. Roc. Soc., 1953, A217:408～432

[7] [7] Dill F H. Characterization of positive photoresist. IEEE Transactions on Electron Devices, 1975, ED-22(7):445～452