Dynamic speckle interferometry of intracellular processes: theory and features of application

The purpose of the work was the link establishment between the parameters characterizing the change phase difference of the wave pairs, passing through the cell and the parameters of the dynamics of speckle. It was assumed that the change in wave phases is caused by microscopic and macroscopic processes in the cell. Optical system is considered in theoretical part. It is consist of the source of coherent radiation, thin transparent diffuser, thin transparent biological object and thin lens which forms an image of the object. It is assumed that the diffuser consists of randomly located scattering point centers. Also, it is assumed that optical path length of single wave: a) changes with time t randomly due to the microscopic processes on the structure level, and b) are determined for the shape change (deformation) of the thin object. An expression for the time autocorrelation function η(t) of the radiation intensity I~ at some point in the observation plane is given. Function η(t) type for stationary and non-stationary change of the path difference of the waves is discussed. Typical experimental dependences I~(t) and η(t) are shown. It is shown that a focused selection of averaging time T allows creating the conditions for obtaining reproducible results, highlighting and analyzing processes occurring in cells at different velocities.