[1] Wang K. Freeform optics for high power LED packages and applications[D](2011).

[2] Han M. Design and application of collimating lens for large-size LED source[D](2016).

[3] Zhan Q J, Liu X Q, Hou Z H et al. Design of TIR collimating lens for ordinary differential equation of extended light source[J]. Proceedings of SPIE, 10460, 104601T(2017).

[4] Meng X X, Liu W Q, Feng R et al. Design of LED collimator for uniform illumination with double freeform surfaces[J]. Acta Photonica Sinica, 43, 0822003(2014).

[5] Wu R M, Chang S Q, Ding Z H et al. Designing two freeform surfaces with Monge-Ampère equation method for point-like sources[J]. Proceedings of SPIE, 10693, 1069306(2018).

[6] Liu Z Y, Wang P P, Jin Z L et al. Free-form lens design for LED fishing lamp with stable illumination[J]. Acta Optica Sinica, 41, 0522003(2021).

[7] Fan R D, Zhao H F, Zeng Y et al. Design of small distortion projection system based on double Gaussian structure and freeform surface illumination[J]. Laser & Optoelectronics Progress, 58, 2322001(2021).

[8] Zhao H F. Research of TIR LED collimation system based on freeform[J]. Proceedings of SPIE, 10255, 102550T(2017).

[9] Mao X L, Li J P, Wang F B et al. Fast design method of smooth freeform lens with an arbitrary aperture for collimated beam shaping[J]. Applied Optics, 58, 2512-2521(2019).

[10] Zeng J, Li X, Ge P. Design of LED collimator for uniform illumination using two freeform lenses[J]. Optica Applicata, 48, 413-420(2018).

[11] Wang Y, Zhang Y, Chen Y F. Design of LED Collimating lens for uniform illumination with freeform surface[C], 20015561(2020).

[12] Kumar H, Velu R, Balasubramanian E. A novel freeform lens design for collimating UV light emitted from an LED with large divergent angle[J]. Optik, 181, 1039-1048(2019).

[13] Zhu Z M, Xu X, Peng B et al. Modeling and design of diffuse transmissive free-form surface based on LED collimation effect[J]. Optics & Laser Technology, 119, 105628(2019).

[14] Luo T, Wang G. Compact collimators designed with point approximation for light-emitting diodes[J]. Lighting Research & Technology, 50, 303-315(2018).

[15] Zeng Y, Zhao H F, Duan W J. Design of optical system with illumination uniform and high distance-height ratio based on double freeform-surface[J]. Acta Optica Sinica, 40, 2422001(2020).

[16] Zhao H, Li C G, Chen Z T et al. Design of collimating lens with uniform illumination for LED based on double freeform surface[J]. Acta Optica Sinica, 37, 0422001(2017).

[17] Chen X D, Lin J P, Liu Z J et al. Aspheric surface lens for LED collimating illumination with low Fresnel loss[J]. Optical Review, 24, 62-71(2017).

[18] Hu T T, Zeng C M, Rui C S et al. Optical design of freeform Fresnel TIR lens for LED uniform illumination[J]. Infrared and Laser Engineering, 50, 20200183(2021).

[19] Zhou Y C, Guo L, Chen Z T et al. Design of collimating lens with multiple freeform surfaces based on total internal reflection structure[J]. Acta Optica Sinica, 41, 0422003(2021).