Fig. 1. Damage morphologies on fused silica surface. (a) Damage at scratch edge^[20]; (b) morphology of damage initiation site^[23]

Fig. 2. Laser-induced damage resistance performances before and after fused silica leaching ^[5]. (a) Damage probability; (b) damage density

Fig. 3. Morphological evolution during etching. (a) Indented pits ^[41]; (b) ground surface^[17]

Fig. 4. Laser damage growth of HF-etched laser damage sites with different sizes after laser irradiation ^[41].（a）Before irradiation；（b）after irradiation

Fig. 5. Surface impurity distributions of fused silica measured by TOF-SIMS at different process stages ^[18]. (a) Before leaching; (b) after HNO₃/H₂O₂ leaching; (c) after HF etching 1 μm; (d) after HF etching 10 μm; (e) after HF etching 50 μm

Fig. 6. Evolution of light intensity distribution on cross-section of optical elements before and after etching ^[20]. (a) (b) Perpendicular to scratch; (c) (d) parallel to scratch

Fig. 7. Evolution of damage resistance performance of elements during etching. (a) LIDT^[49]; (b) damage probability^[42]; (c) damage density^[18]

Fig. 8. Damage density comparison after AMP2 and AMP3 processing ^[50]