New technique for solving the integral equation of the surface laser intensity modulation method (SLIMM)

One of the most difficult problems in the use of the Surface Laser Intensity Modulation Method (SLIMM) or the Laser Intensity Modulation Method (LIMM) is the solution of the Fredholm integral equation of the 1st kind which describes the frequency dependence of the pyroelectric current. Multiple and very different polarization distributions can be obtained when this equation is solved using experimental data. The constrained regularization method has been used successfully to solve this problem. However, the choice of the proper regularization parameter is normally somewhat arbitrary and this can drastically affect the solution. In the new technique, an optimal regularization parameter is found using a set of simulated data based on a polarization distribution constructed from a simple frequency-to-space transformation. The technique is illustrated with experimental data measured on PLZT ceramics.