Fig. 11. 3D images of calculated RL values and RL curves of FC-700 (a and a1), HFC-700 (b and b1), HFC-800 (c and c1) and HFC-900 (d and d1). The bottoms of (a1–c1) are emulations of the absorber thickness (d_m) vs. peak frequency (f_m) for HFC-700, HFC-800 and HFC-900 under the λ/4 model.