Sensitivity of the thermocapillary method of thickness determination for transparent liquid films on horizontal absorbing substrates

We present data on the sensitivity of a new method of determining the thicknesses of thin films on flat horizontal substrates, based on the measurement of a stationary thermocapillary response. In the range of film thicknesses exceeding the thermocapillary rupture thickness by no more than 10 μm, the error of the film thickness determination is no greater than 1–2 μm. By increasing the power of the laser beam inducing the thermocapillary convection from 3.5 to 16.5 mW, it is possible to keep the relative error of measurement within 5% in the range of film thicknesses from 150 to 1000 μm for liquids with viscosities within 0.8–5.6 cSt.