Development and application of spatial carrier interferometry for whole field real-time investigation of temperatures in liquid media

This paper presents interferometric measurement of dynamic phenomena in transparent media. The method is based on differential spatial carrier interferometry that provides interesting features for experimental fluid mechanics. The method is particularly suitable for progressively changing phenomena. Temperature is automatically evaluated from a single interferogram, and a differential approach allows to decrease dynamic range of the measurement. As a consequence, in case of high temporal sampling of the phenomena, no spatial phase unwrapping is needed. Otherwise, the spatial unwrapping is performed on low fringe density phase maps and the fringe order is unambiguously determined. The interferometric method was experimentally tested by measuring dynamically varying temperature fields in water. The inspected phenomenon was a convection of water layers within a glass tank, where a heat sink was positioned at the bottom of the tank. Interferometric and temperature measurements were simultaneously conducted. Temperature was measured using four thermocouples to verify the reliability of the method. Results of both approaches are in a good agreement.
Water, Interferometry, Spatial carrier, Fourier transform, Temperature field, Convection