Introduction

Liquid crystal thermography is a convenient technique that can provide temperature distribution over the entire test surface. It can be configured to yield the heat flux variation as well. Since the liquid crystals employed have a reasonable temporal response, temperature and heat flux variations can be measured, in many contexts, as a function of time. Since the response to changes in temperature originates from laser-matter interaction, LCT is also classified as a light scattering technique. Traditional techniques employing sensors such as thermocouples and resistance thermometers can measure temperature at individual locations. Hence, a large number of sensors are required for complete mapping of the surface. Since physical sensors occupy space, the measurements are to be interpreted as spatial averages. This route may prove to be disadvantageous in regions of localized peaks and valleys of heat transfer. Liquid crystal thermography proves to be useful under these circumstances.