We developed an optical frequency domain imaging (OFDI) system based on an integrated thermo-optic swept laser to achieve three-dimensional surface imaging. The wavelength was swept by applying a heating signal to a thermo-optic polymeric waveguide. The sub-micrometer surface profile was converted from the three-dimensional phase information of the OFDI system on various samples used as resolution targets with a step height of 120 nm. © 2014 IOP Publishing Ltd.