Fig. 1. Theoretical simulation results of tri-layer broadband antireflection coatings. (a) Change refractive index of middle layer; (b) change refractive index of top layer

Fig. 2. Refractive index of single layer. (a) Refractive index of coating measured by ellipsometer; (b) test and theoretical transmittance of layer

Fig. 3. Effect of heat treatment time on coating. (a) Variation of transmittance of coating with heat treatment time; (b) transmittance curve of tri-layer broadband antireflective coating

Fig. 4. Antireflection properties of tri-layer coatings. (a) Transmission and simulation curves of λ/4-λ/2-λ/2 tri-layer broadband antireflective coating; (b) transmittance curves of coating at different incident angles; (c) oblique incident average transmittance gain of λ/4-λ/2-λ/2 and λ/4-λ/2 broadband antireflective coatings

Fig. 5. Surface roughness of coating. (a) Bottom layer; (b) middle layer; (c) top layer; (d) tri-layer broadband antireflection coating

Fig. 6. Transmittance spectra of tri-layer broadband antireflective film before and after rubbing experiment