Fig. 1. Technical index requirements of light filter device before energy attenuation

Fig. 2. Sensitivity values of different spacer materials

Fig. 3. Theoretical spectral curve of 1064 nm filter film with single-sided design

Fig. 4. Theoretical spectral curve of broadband cut-off film with single-sided design

Fig. 5. Theoretical spectral curve of 1064 nm narrowband filter device with double-sided film design

Fig. 6. Refractive receiving optical system

Fig. 7. Reflectivity curves of different metals with same transmittance

Fig. 8. Comparison between designed curve and theoretical curve. (a) Narrowband filter film; (b) broadband cut-off film

Fig. 9. Test curve of high-transmittance filter device after Tooling value correction

Fig. 10. Refractive index and extinction coefficient versus film thickness

Fig. 11. Comparison of transmittance values of Cr films with different thicknesses before and after attenuation

Fig. 12. Actual transmittance versus Cr film thickness

Fig. 13. Transmittance curves before and after deposition of 25 nm thick Cr film

Fig. 14. Spectra of sample before and after environmental testing