Thermal-wave Field Research Articles

Theory of photothermal-wave diffraction and interference in condensed media

Thermal-wave field diffraction has been treated as the extreme near-field approximation of a three-dimensional superposition integral that includes the generating optical aperture function. This formalism is quite general and is convenient for applications with many experimental diffracting apertures. Specific examples of useful photothermal excitation apertures have been treated explicitly. These include the spatial impulse function, a Gaussian laser beam, a circular aperture, and an expression for the interference field generated by two Gaussian laser beams.

Hamilton–Jacobi formulation and quantum theory of thermal wave propagation in the solid state

A mathematical formalism has been developed for the description of the propagation of thermal waves in solids. The theory is based on the analogy between thermal waves and mechanics as manifested upon expressing the heat conduction equation in the Hamilton–Jacobi formalism. The transition of the classical formulation to quantum mechanics is accomplished by defining thermal wave operators for the generalized coordinates and the canonically conjugated momenta. The resulting theory shows that propagating, albeit heavily damped, thermal waves can be formally described by a quantum mechanical thermal harmonic oscillator (THO). The expectation values of observables, derived from Ehrenfest’s theorems, are found to be of practical importance for the description of the thermal wave field in solids with inhomogeneous thermal and thermodynamic properties.