Near-field radiative heat transfer between two parallel SiO2 plates with and without microcavities

Near-to-far-field radiative heat transfer between two macroscopic SiO2 plates-with and without microcavities-was observed using a highly precise and accurate optical gap-measurement method. The experiments, conducted near 300 K, measured heat transfer as a function of gap separation from 1.0 mu m to 50 mu m and also as a function of temperature differences between 4.1 and 19.5 K. The gap-dependent heat flux was in excellent agreement with theoretical predictions. Furthermore, the effects of microcavities on the plate surfaces were clearly observed and significant enhancement of near-field radiative heat transfer was confirmed between gold-coated microcavities with narrow vacuum separation. (C) 2015 AIP Publishing LLC.