| 摘要 |
PURPOSE:To increase the variable amt. of refracting power and to enable easy removal of the adverse influence by the intricate deformation of a refracting face by deforming a transparent elastic material formed preliminarily and internally with a nonuniform refractive index distribution. CONSTITUTION:The inside diameter of a cylindrical piezoelectric element 2 enclosing the circumference of an elastic material 1 can be changed by impressing a voltage thereto. For example, when the inside diameter decreases, the surface 6 of the material 1 existing at the open end of the cylindrical piezoelectric element increases further the convexity and if the refractive index distribution formed preliminarily in the material 1 is assumed to have a positive refracting powder, the positive refracting power increases further and the refracting power changes largely as a whole. The elastic material having so-called high elasticity is desirable; for example, silicone rubber and ethylene propylene rubber are most preferable in terms of transparency. Such high-elasticity rubber has a Poisson's ratio of as high as 0.45-0.49 and has a small volume change. The refractive index at each point in the elastic material is therefore virtually the same before and after the deformation and the refractive index is determined only by the movement owing to the deformation at each point.
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