Experimental determination of the absolute temperature modulation in photothermal microscopy of Y1Ba2Cu3O7 crystals

Abstract
We present a technique to experimentally determine the value of the temperature perturbation δT in photothermal microscopy. Knowledge of δT is necessary for proper analysis of the differential optical reflectivity (∂R/∂T) data obtained from untwinned Y1Ba2Cu3O7 crystals. We measure δT to be 0.2 K, consistent with previous theoretical predictions from thermal diffusion data.