THERMAL OPTICAL EFFECTS IN NSOM PROBES

The coupling of thermal and optical effects in near-field scanning opt ical microscope (NSOM) fitted with a coated tapered fiber probe is con sidered. Heating of the probe occurs due to the absorption of light in the metal coating in the tapered region of the probe at relatively la rge (tens of microns) distances from the probe apex. Conduction of hea t that occurs with a time constant of tens of milliseconds results in an elevated probe temperature over a rather large region of the taper, This in turn, affects the optical throughput of the NSOM. Experimenta l measurement of thermal/optical coupling and a discussion of coupling mechanisms is included.