Imagine that an interface of a transparent and an absorbing media is irradiated with nanosecond laser pulses from the side of the transparent medium along the surface normal (positive View the MathML source direction, z = 0 corresponds to the absorbing medium surface). The wavefront of the optical radiation can be considered as plane when the light penetration depth dop is much smaller than the laser beam diameter d. The thermal confinement condition is fulfilled very well for most of dielectric media when nanosecond laser pulses are used for OA signal generation [18], i.e