Fig. 1. Principle of focusing performance measurement of Fresnel lens with large aperture and short focal length

Fig. 2. Experimental devices for optical performance measurement of Fresnel lens. (a) 450 nm LD; (b) 532 nm LD

Fig. 3. Focusing efficiencies for 450 nm and 532 nm lasers passing through different Fresnel lens surfaces with incident angles of 0°-30°. (a) Smooth surface; (b) serrated face

Fig. 4. Focusing efficiencies for 450 nm and 532 nm lasers vertically incident on Fresnel lens with serrated face

Fig. 5. Focusing efficiencies for 450 nm and 532 nm lasers passing through Fresnel lens with incident angles of -30°-30°

Fig. 6. Focusing spots for 450 nm laser passing through Fresnel lens with incident angles of 0°-30°. (a) 0°; (b) 5°; (c) 10°; (d) 15°; (e) 20°; (f) 25°; (g) 30°

Fig. 7. Focusing spots for 532 nm laser passing through Fresnel lens with incident angles of 0°-30°. (a) 0°; (b) 5°; (c) 10°; (d) 15°; (e) 20°; (f) 25°; (g) 30°