Defects Induced In Optical Surfaces By The Diamond-Turning Process

Abstract

The development of high fluence laser diagnostics and other methods has resulted in a wealth of data on the surface and optical properties of diamond-turned metal mirrors. From this data, it has been determined that the diamond-turned surface exhibits unique proper-ties which are related empirically to the machining conditions. Among these are optical reflectance changes and variations in the laser damage thresholds of melt, slip, and selec-tive area damage. The plastic deformation of the surface during diamond machining results in a higher concentration of crystalline defects in the near-surface region that contrib-utes to the reflection process. This paper presents the results of an investigation into the nature of the deformation introduced by the diamond-machining process. In particular, the structure of the surface region is elucidated by high resolution transmission electron microscopy. In addition, the correlation of the various observed defects to the physical properties of the surface will be discussed.