Random Packed Optical Fiber Bundle for Homogenizing the Energy Distribution in a Laser Beam on the Specimen Surface and its Application to the Thermal Diffusivity Measurements

Abstract

Ruby lasers usually employed in the laser flash method for measuring thermal diffusivity of various inorganic substances are known to have the inhomogeneous energy distribution and their particular spatial intensity structure significantly effects the quantitative accuracy of the resultant thermal diffusivity data in some cases. Random packed fiber bundle made of plastic optical fiber with plastic optical guiding rod has been developed for homogenizing the energy distribution in a laser beam on the specimen surface. The usefulness of this new device has been well approved by measuring the energy distribution and the thermal diffusivity of nickel disc.