Characterization of surface and sub-surface defects in optical materials using the near field evanescent wave

Technical Report · Thu Dec 31 04:00:00 EST 1998

DOI:https://doi.org/10.2172/334222· OSTI ID:334222

Yan, M; Oberhelman, S; Wang, L; Siekhaus, W; Kozlowski, M

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., 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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COATINGS
DAMAGE
DATA
DEFECTS
LASERS
MICROSCOPY
OPTICAL SYSTEMS
SILICA