Analysis of High-Order Harmonics of Temperature Wave for Fourier Transform Thermal Analysis

Abstract

The high-order harmonics of temperature wave were detected in a thin film by inputting a square pulse train with a variable duty factor to generate temperature modulation. In Fourier analysis, the harmonics were observed up to the 42 th order and the mathematical rule was experimentally confirmed. This principle was applied to a technique called “Fourier transform thermal analysis,” which made it possible to determine simultaneously thermal diffusivity and heat capacity per unit volume as a function of frequency and temperature.