Optical Processing Damage Reduced by Polishing Technology with Material Removal in Elastic Mode

Abstract

Surface/subsurface processing damage on optical component can severely affect its surface mechanical properties and cause its resistance to external deformation to deteriorate. At the same time, the processing damage will also affect the surface quality. The surface processing defects are the main reasons leading to the decrease in the laser induced damage threshold in high-density laser system. In this paper, the damage formation mode and morphology of the traditional optical processing methods based on the mechanical removal in brittle and plastic modes are evaluated, then the traditional processing damage model is established accordingly. The polishing technology with material removal in elastic mode is proposed based on the damage generation mechanism. In the elastic mode, it is impossible to form the material removal by mechanical action due to the inability to overcome the yield limit of the material, thus it is necessary to introduce a weakening of the chemical reaction to reduce the bonding force of the surface layer of the optical element, using less force to form the material removal to ensure the disturbance of the basic material is controlled. The mechanism of material removal in elastic mode was analyzed. The polishing process was realized by elastic hydrodynamic ultra-smooth polishing and nano-particle jet polishing. The performance of the elastic polishing process was analyzed. The experimental results show that the elastic polishing processing method can effectively remove surface damage and achieve effective control of processing damage.

Mechanism of Surface Hydroxylation Acceleration and Laser-Induced Damage Threshold Reduction during Ion Beam Sputtering of Fused Silica

“…Molecular dynamics simulations were used in Ref. [20] to show that the band gap on the silica surface is significantly smaller than that of the bulk structure (Figure 4), indicating that surface atoms are more likely to have chemical reactions with external atoms than the bulk atoms. Previous studies have shown that when the IBS removal depth is g nm, ion sputtering damage will occur in the shallow layer of fused silica overall photothermal weak absorption intensity of the HF acid-etched s duced by IBS, the structure damage on the shallow surface caused by sp ates the change in material characteristics, which further improves the ph absorption intensity of the corresponding area after immersion.…”

“…Molecular dynamics simulations were used in Ref. [20] to sho gap on the silica surface is significantly smaller than that of the bulk stru indicating that surface atoms are more likely to have chemical reactions oms than the bulk atoms. On the other hand, the waviness of microscopic fluctuations on the solid surface is mainly manifested in the form of lattice defects, vacancies, and dislocations at the atomic scale.…”

“…Infrared spectroscopy is the main way to study the OH-group structure characteristics of fused silica. The absorption peak in the infrared spectrum corresponds to the vibrational form of the OH-group, and the characteristic absorption peak near 3660 cm −1 indicates the presence of OH-groups [20]. A Bruker Vertex70 (Bruker Corporation, llerica, MA, USA) high-resolution Fourier transform infrared spectroscopy (FTIR) was used to measure the hydroxyl content after different surface treatment methods.…”