We determined the extinction ratio of a polarization analyser on the basis of Malus' law by relating the transmitted light intensity to the analyser azimuth measured at only a small range of analyser azimuth angles around the minimum position, thus avoiding the requirement for an optical detector with a high dynamic range. To adjust the orientation of the analyser azimuth we manufactured a precise rotation stage which had an angular resolution of less than rad. The minimum value of the extinction ratio was , obtained for a polarization analyser of the Glan - Taylor type. To calibrate the apparatus we measured the Faraday rotation of a glass plate placed in a magnetic field in the optical path.

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Optical birefringence in liquid-phase-epitaxial-grown (LPE) Bi-substituted iron garnet films was investigated with annealing. The optical birefringence was found to be composed of a stress-induced part and a growth-induced part. The growth-induced optical birefringence Δng was about 5×10−4 at λ=1.15 μm. Δng and the growth-induced magnetic anisotropy Kg disappeared after the annealing. Time constants for changes of Δng and Kg by the annealing were nearly the same and orders of a few hours at 1100–1150 °C. A deformation of the microscopic structure around bismuth ions seems to be responsible for both Δng and Kg. The large growth-induced optical birefringence in Bi-substituted iron garnet films plays an important role to achieve high efficiency TE-TM mode conversion in magneto-optical waveguides.

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We present a design procedure for symmetrically laminated composite structure with GA (Genetic Algorithm) and finite element analysis. Design variables to enhance the rigidity of the laminated composite structure are the number of laminae, the fiber orientation and the stacking sequence. Here, the fiber orientation is selected among some prepared angles from a manufacturing viewpoint. In a conventional design procedure based on GA an objective function is calculated by costly finite element analysis. Consequently, it is quite time consuming and unpractical. In this paper, to minimize the displacement at a point in the structure, we define an approximated rigidity function of the laminated composites by means of weighing coefficients and transformed elastic moduli in the prepared angles. The weighing coefficients are initially determined using the distribution of principal stress in the structure under an applied load. Then, we can guess that reinforcements should be oriented according to the weighing coefficients with which the rigidity function takes maximum. To find the global optimum solution, the weighing coefficients are adjusted with as small a number of finite element analyses as possible. As a conclusion, the proposed procedure can reduce the computational cost remarkably compared to the conventional one, and can be applied practically to arbitrary shaped structures.