Fig. 1. Principle diagram of lens coupler

Fig. 2. Design diagram of paraxial incident plane of lens coupler

Fig. 3. Intensity distribution curves of LED with a primary lens

Fig. 4. Design diagram of paraxial exit surface of lens coupler

Fig. 5. Working principle diagram of free-form total reflection surface

Fig. 6. Ray tracing light path of paraxial incident surface of lens coupler to point light source

Fig. 7. Energy distribution of point light source on the receiving screen after passing through the paraxial incident surface. (a) s=7 mm; (b) s=8 mm; (c) s=9 mm; (d) s=10 mm

Fig. 8. Energy distribution of the 3535 LED light source on the receiving screen after passing through the paraxial incident surface

Fig. 9. (a) Output light energy distribution curve and (b) compensation curve of the 3535 LED light source passing through the paraxial refracting surface

Fig. 10. 3D model of lens coupler

Fig. 11. Output intensity distribution of lens couple. (a) x-y plane; (b) cross section at y=0

Fig. 12. Final light intensity distribution curve