Fig. 1. Structure diagram of scale lens

Fig. 2. Light path diagrams of transverse and longitudinal sections of scale lens. (a) Light path diagram of transverse section; (b) light path diagram of longitudinal section

Fig. 3. Uniform illumination principle of scale lens

Fig. 4. Design principle of free-form surface.(a)Refraction diagram of free-form surface；(b) refraction diagram of P-point

Fig. 5. Design of scale structure

Fig. 6. Spectra of red and blue LEDs. (a)Spectrum of blue LED; (b) spectrum of red LED

Fig. 7. LED light sources are arranged in two ways. (a) Blue LEDs are equally arranged in two columns; (b) red and blue LEDs are evenly arranged

Fig. 8. Spectra of LED light sources in two arrangement modes. (a) Uniform arrangement in two columns of blue LEDs；(b) uniform arrangement of red and blue LEDs

Fig. 9. Light distribution curve and PPFD diagram of LED plant lamp.(a)Light distribution curve; (b)PPFD diagram

Fig. 10. Influence of scale bulge height H on PPFD uniformity and optical efficiency of receiving surface

Fig. 11. Influence of scale width D on PPFD uniformity and optical efficiency of receiving surface

Fig. 12. Schematic of spacing B between two LEDs center columns

Fig. 13. Influence of B value on PPFD uniformity and optical efficiency of receiving surface

Fig. 14. Light distribution curve and plane illumination distribution of LED plant lamp. (a) Light distribution curve; (b) plane illumination distribution

Fig. 15. Experimental light distribution curve of LED plant lamp

Fig. 16. Image of red and blue LEDs evenly arranged

Fig. 17. Spectrum testing with uniform arrangement of red and blue LEDs. (a) Handheld UPRtek spectrometer used in testing; (b) PPFD diagram of LED plant lamp light source

Fig. 18. Physical drawing of LED plant lamp with lens

Fig. 19. Light distribution curve of LED plant lamp in whole lamp experimental test

Fig. 20. PPFD diagram of whole lamp experimental test of LED plant lamp