@article{DING Yi:173, author = {DING Yi, GU Peifu}, title = {Freeform optical element for uniform illumination}, publisher = {Front. Optoelectron.}, year = {2008}, journal = {Frontiers of Optoelectronics}, volume = {1}, number = {1-2}, eid = {173}, numpages = {4}, pages = {173}, keywords = {freeform optical element; uniform illumination; partial differential equation sets; numerical solutions}, url = {https://journal.hep.com.cn/foe/EN/abstract/article_8499.shtml}, doi = {10.1007/s12200-008-0013-5} }