A new technique has been developed for investigation of optical dispersion of either natural or stress-induced birefringence. A spectropolarimeter containing a computer-controlled monochromator and two plane polarizers records polariscopic images of a sample via a TV-camera and a video frame grabber in two polarizer configurations: parallel and crossed. From this technique, one may calculate a map of a certain dispersion parameter over the entire sample area, and can plot it as a function of the wavelength for an arbitrary sample point. This technique has been found to be useful for investigation of optical inhomogeneities involved in crystals by gamma and proton irradiation, as well as by the native crystallographic imperfections.

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In this work the paraxial optical imaging is generally described by means of three square matrices: one unitary system matrix and two operation matrices with determinants equal the Lagrange-Helmholtz invariant. Elements of system matrix are functions of design parameters while elements of the operation matrix depend on input and output coordinates of characteristic rays. Each matrix has only three independent elements. Internal system parameters are determined from equations created of system matrix elements, which values are dependent on the operation matrix. Matrix approach enables the solution of only three non-linear equations with respect to system parameters. Matrix approach has also another advantage. It enables the determination of number of degrees of freedom. We have a superiority of parameters over the number of equations when the number of components is bigger than 2. The more complex is model the higher degree of freedom it has. There are special ways of reducing the number of degree of freedom: by selection of spaces between component, introduction of additional requirements and criteria of distribution of optical powers. Significant help is in defining all the spaces between components, what means full control of the components position and their dimensions. In such a case the only thing left is the determination of optical powers, while the number of degree of freedom is equal k-1 (k is the number of components). In this work the computer program realizing described algorithms has been developed. This program was tested with specially selected examples. Results of calculation for two interesting applications are also given.

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