One can create conical microlens arrays on a glass plate by simply spin coating spin-on-glass film on the glass, patterning the photoresist, and then etching the glass in a HF solution. These arrays can be used to obtain more-uniform irradiance profiles from nonuniform incoherent sources.
© 1995 Optical Society of America
Jeong-Keun Ji and Young-Se Kwon, "Conical microlens arrays that flatten optical-irradiance profiles of nonuniform sources," Appl. Opt. 34, 2841-2843 (1995)