Temperature effects in the focal region of acoustic microscope

New analytical expressions that account for radial and axial heat flow in a medium and immersion liquid are derived for the case of a Gaussian-shaped ultrasonic beam pattern near a focus of an acoustic microscope in thin or semi-infinite absorbing materials for two cases corresponding to the studying of biological or solid-state samples. In the first case, it is assumed that the sample together with the immersion represents a medium uniform in its thermal properties. In the second case, it is supposed that heat conductivity of a sample material is much more than that of the immersion liquid. Solutions are given for temperature growth along the axis of symmetry of acoustic lenses. The use of these equations in estimation of the temperature growth gives a maximum value of one degree for biological samples with the absorption coefficient ten times more than that of water and 10/sup -3/ degrees C for samples of silicon for the microscope with a maximum ultrasonic intensity of 10/sup 3/ W/cm/sup 2/ at 500 MHz and with water as an immersion liquid.<>