Confocal microscopy of electro-optic materials: effect of aberrations on the axial response in ac mode

Confocal scanning optical microscopy can be used to investigate the structu re of electro-optic materials. Application of an ac electric field allows o ne to measure sensitively small changes in the reflection of light from a s ample surface, and those changes can be related to the electro-optic proper ties. We observe the axial dependence of the ac light intensity to be a lin ear combination of the de component and its axial derivative. Our analysis shows that astigmatic aberrations and the azimuthal dependence of the optic al index in anisotropic materials can explain this behavior. (C) 2000 Optic al Society of America [S0740-3232(00)01301-7]. OCIS codes: 180.1790,180.581 0.