Fig. 1. Dark field image of contaminated large-aperture vacuum separator

Fig. 2. Number of surface particles on the contaminated large-aperture vacuum separator

Fig. 3. X-ray photoelectron spectroscopy of surface particles on the contaminated large-aperture vacuum separator (CPS: Counts per second；B.E.: Binding energy)

Fig. 4. Schematic diagram of the laser cleaning system for large aperture optics

Fig. 5. Number of residual particles on the contaminated vacuum separator after laser cleaning process under different laser energy density. (a) Border zone of vacuum separator; (b) Central zone of vacuum separator

Fig. 6. Dark field image of border zone on vacuum separator before and after laser cleaning. (a) Unprocessed; (b) Post processed with laser cleaning method (1.71 J/cm² laser density)

Fig. 7. Dark field image of central zone on vacuum separator before and after laser cleaning. (a) Unprocessed; (b) Post processed with laser cleaning method (1.71 J/cm² laser density)

Fig. 8. Schematic diagram of the large aperture optics laser cleaning setup with the airflow displacement system

Fig. 9. Comparison of surface particles removal rate of different samples laser cleaning with or without the airflow displacement method

Fig. 10. Microscopy comparison of surface particles with or without the airflow displacement method. (a) Dark field microscopy without the airflow displacement; (b) Dark field microscopy with the airflow displacement; (c) Bright field microscopy without the airflow displacement; (b) Bright field microscopy with the airflow displacement