Fig. 1. Variation curves of refractive index and extinction coefficient of Ge and Al₂O₃ films

Fig. 2. Theoretical design spectral curve of MWiR notch filter

Fig. 3. Variation of theoretical spectral transmittance of films with incident angle

Fig. 4. Theoretical design and measured spectral curves of (LH) ⁴L multilayer film structure under fixed scale factor

Fig. 5. Relative error distribution of each film

Fig. 6. Design and measured spectral curves of MWiR notch filter film obtained based on the modified scale factor

Fig. 7. Measured transmission spectrum curve after double-sided coating

Fig. 8. Surface morphology graphs before (a) and after (b) coating

Fig. 9. Surface profile change before and after coating without surface profile compensation (a, b) and with surface profile compensation (c, d)