Fig. 1. Model of the freeform lens

Fig. 2. Effect of the lateral shift δ on lens

Fig. 3. Schematic diagram of internal focusing optical system

Fig. 4. [in Chinese]

Fig. 4. MTF of optical system with different object distance

Fig. 5. Displacement of vertical deflection with different object distance

Fig. 6. Amount of compensation at different image distance

Fig. 7. [in Chinese]

Fig. 7. MTF diagram of optical system with different imaging conditions