Influence of sound on energy transfer in light-induced gratings
A theoretical study is made of the possibility of controlling the process of energy transfer in lightinduced gratings by the action of acoustic vibrations. The exact solution is obtained of a nonlinear system of reduced equations for the complex amplitudes of light waves in the presence of sound. An analysis of the solution shows that sound can alter radically the process of energy transfer from one wave to another. Conditions are found under which complete energy transfer can be achieved in samples of finite and realistic thicknesses, when this is not possible in the absence of sound. A numerical calculation is reported and the dependence of energy transfer on the initial conditions is illustrated graphically.
We have acquired in vivo photoacoustic images of gastrointestinal tracts in rats using recently developed clinical photoacoustic/ultrasound imaging system. The result can be used to investigate motility of gastrointestinal tracts in clinical studies.