On the new potentials of ellipsometry arising from the null optical circuit. Ellipsometry of real surface structures. 19. Optimal solution choice of inverse problem in studying of ultra thin superficial films

A new approach to the solution of mathematically incorrect inverse problem of elipsometry for ultra thin superficial films based on the using of measurements corresponding to angles of incidence set of a light beam is proposed. Parameters-criterion are introduced which allow to find the optimal solution of an inverse problem, the nearest to the exact solution. The results of the numerical experiment showed the great accuracy of the optimal solution during parameters determination of ultra thin films. The errors influence in assigning substrate optical constants on the accuracy of the optimal solution is studied. The general analysis of features of the inverse problem of simultaneous parameters determination of a reflecting single-layer system with ultra thin films is given.