DUAL-OPTICAL-MODE NEAR-FIELD SCANNING OPTICAL MICROSCOPY

The simultaneous operation of near-field scanning optical microscopy ( NSOM) in reflection and transmission modes is demonstrated. In the tra nsmission mode, a low-noise, large-area silicon photodetector was moun ted between the piezoelectric transducer scanning stage and the sample . In the reflection mode, either a photomultiplier tube or two large-a rea silicon detectors was used for signal collection. The reflection-m ode setup consisting of two silicon detectors provides a large numeric al aperture of 0.9 as well as symmetrical detection of emitting photon s. The dielectric thin films and the light-emitting polymers were used to demonstrate the capability of these two modes of NSOM. A compariso n between these two different setups is also presented. (C) 1996 Optic al Society of America