Fig. 1. Self-supporting Al filter prepared by two release agents

Fig. 2. Calibration sample

Fig. 3. Al film thickness calibration result

Fig. 4. SEM images of Al filter

Fig. 5. Pinholes of Al filter

Fig. 6. The transmittance of Al filters prepared by different release agents in ultraviolet，visible and infrared bands

Fig. 7. Comparison of transmittance between 80 nm self-supporting Al filter and 400 nm PI + 80 nm Al filter

Fig. 8. The transmittance of Al filter prepared with two kinds of release agents in soft X-ray band and the comparison with the theoretical value

Fig. 9. Comparison between the measured and theoretical values of the filter in the energy range of 50~250 eV

Fig. 10. XPS test results of Al filters prepared by two release agents