Experimental investigation of nonuniform heating and heat loss from a specimen for the measurement of thermal diffusivity by the laser pulse heating method

Nonunilbrm heating effect and heat loss effect from the specimen in the mcast, rement of thermal diffusivity by the laser pulse heating method have been experimentally investigated using an axially symmetric Gaussian laser beam and a laser beam homogenized with an optical filter. The degree of error is theoretically estimated based on the solution of the two-dimensional heat conduction equation under the boundary condition of heat loss from the surface of the specimen in the axial direction and the initial conditions of axially symmetric nonuniform ~tnd unilbrm heating. A correction factor, which is dctcrmined by comparison of the entire experimental and the theoretical history curves, is introduced to correct the values obtained by the conventional t~ ~ method. The applicability of this modilied curve-fitting method has been experimentally tested using materials in the thermal diffttsivity range 10 _3 to [ cm-ʹ .s i. The experimental error due to the nonuniform heating and heat loss was reduced to approximately 3%.