Approximate Method for Modelling Laser Light Scattering from Biological Cells

摘要

A new technique for approximating the scattering of laser light by biological cells is reported. This technique is based on a three-dimensional scalar wave equation approximation of the full Maxwell's field equations for the electromagnetic field. This scalar wave equation for describing the light scattering patterns of cells containing arbitrary morphological structure (e.g., various organelles) is solved numerically using a spectral method. The accuracy of the spectral numerical method is verified by comparison with solutions obtained from linear perturbation theory and Mie theory. Comparison with Mie theory shows that the three-dimensional scalar wave equation is a good approximation to the full Maxwell's field equations for light scattering up to moderate forward scattering angles (i.e., for scattering angles less than about 350). The approximate technique used here is capable of correctly predicting the scattered intensity patterns from biological cells over a dynamic range spanning six orders of magnitude. The new technique can be applied to calculate the light scattering either from an individual biological cell and from a sample containing an ensemble of such biological cells. The scattering intensity patterns predicted using the new technique can potentially be applied to diagnose the size and internal structure of biological cells, making it a valuable interpretative tool in flow cytometry (e.g., in the detection of rare event cells such as those resulting from a biological warfare agent attack, or for the rapid noninvasive optical assessment of tissue pathology in the detection of cancerous cells).