Laser-Induced Thermal Effect on Sensitivity of Scanning Near-Field Optical Microscope Probe

Abstract

In this study, the laser-induced thermal effect on the sensitivity of a scanning near-field optical microscope (SNOM) tapered probe is analyzed. In the analysis, the thermal effect can be considered as an axial force and is dependent on the temperature distribution of the probe. The Rayleigh–Ritz method is used to determine the sensitivity of the probe. According to the analysis, the sensitivity of the first three vibration modes increases when the thermal effect is taken into account. When the contact stiffness is low, the thermal effect on the sensitivity of mode 1 is particularly significant. The sensitivity of mode 1 increases with increasing taper angle and coating thickness of the probe. In addition, the effect of a SNOM probe with three different coating materials, Al, Au, and Ag, on the sensitivity of mode 1 is studied. The result shows that the highest sensitivity is obtained for the probe with an Al coating, whereas it is the lowest with a Au coating.