Abstract: A method for the optical measurement of a variation in temperature of an object (O) includes: an emission step (S1) consisting of emitting, in the direction of the object (O), a first incident electromagnetic wave (W1_inc) of the terahertz type, and a measurement step (S2) including the measurement (S2_3), by a sensor sensitive to terahertz radiation (20), of a variation in amplitude of the electromagnetic radiation of a second electromagnetic wave (W2_ref, W2_tra) in order to determine the variation in temperature of the object (O).

Abstract: Composite material for storing heat energy at high temperatures (225° C. to 488° C.) formed by a porous carbon structure at least partially filled with LiOH/KOH, wherein a large amount of heat energy may be stored or released very quickly. The carbon structure is characterised by a high volumetric thermal conductivity, a low density, a highly interconnected porosity and a relatively high modulus of elasticity. The significant properties of LiOH/KOH mixtures are: a large amount of energy involved in full melting/crystallisation, a fairly low relative volume expansion upon melting and fairly low subcooling. The main advantages of the resulting composites are a very high energy density, a relatively low volume expansion, highly enhanced heat transfer, thermoadaptability, stability and insignificant hysteresis.