This thesis discusses the thermal behavior of the STM tip under laser irradiation. The thermal expansion of the tip was researched with varying laser spot size, frequency, location, and power. In order to determine the thermal expansion of the STM tip, the behavior in both the time and frequency domain were investigated. By employing the FFT analysis, the noise of the thermal behavior in the frequency domain was greatly reduced when compared to the time domain behavior, allowing for higher resolution expansions. With noise reduced, a thermal expansion of 1 nm, equating to a 0.03 K average temperature rise across the tip was found. Besides the heating and expansion of the STM tip, the thermal diffusivity of the PtIr STM tip was calculated using the TET and Characteristic Point methods, and found to be within 3% of the expected value.