Characterization of surface and sub-surface defects in optical materials using the near field evanescent wave
Optical properties of sub-micron defects at and near the surface are of interest in many applications, e.g. in high power laser systems where initiation of laser induced damage is a critical issue. In-situ scanning atomic force microscopy (AFM) has been used previously to establish a direct correlation between a particular structural surface inhomogeneity (such as a nodular defect in coatings) and the initiation of local laser damage at that inhomogeneity. Near field scanning optical microscopy (NSOM) make it now possible to provide information on both morphology and optical properties of localized defects at and near the surface. The authors have measured the amplitude variation of the near field evanescent wave around nodular defects and sub-surface inclusions in optical coatings and thus detected local laser field intensification. The observed intensity variation of the evanescent wave agrees with theoretical calculations of laser amplification around the inclusion. These findings support the theory that laser damage may be induced by local electrical field enhancement associated with micron and sub-micron defects.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 334222
- Report Number(s):
- UCRL-JC-131225; ON: DE99002434; TRN: AHC29914%%26
- Resource Relation:
- Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Defect studies of optical materials using near-field scanning optical microscopy and spectroscopy
Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces