The illumination of a sample when imaged by thermoreflectance thermal microscopy may cause significant heating of the surface. Nonlinearities in the performance of the system being imaged may lead to large measurement induced errors in the observed temperature field. Analytical expressions are presented to estimate the temperature rise and heat flux in a sample. Spatially filtered thermo-reflectance microscopy is introduced as a technique to significantly reduce the incident heat flux without loss of spatial resolution. This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.