ELECTROMAGNETIC-FIELD EXPRESSION OF A LASER SHEET AND THE ORDER OF APPROXIMATION

The laser sheet (Gaussian beam with an elliptical cross-section) is a powerful tool in optical particle characterization such as in PIV or d ual cylindrical wave devices. In order to be able to predict the prope rties of such devices, an approximate description of laser sheets is i ntroduced. The involved approximation order is then discussed in Carte sian and spherical coordinate systems. It is found that the expression s obtained obey the vector potential equation, the Maxwell equations, and the Bromwich formalism at order O(s2), in which s is a characteris tic dimensionless parameter. The approach proposed in this paper may b e applied to other shaped beams.