GB449186A - Improvements in or relating to lenses - Google Patents

Abstract

449,186. Spectacle lenses. TENNANT, W. J., 111, Hatton Garden, London.- (American Optical Co. ; Southbridge, Massachusetts, U.S.A.) Dec. 21, 1934, No. 36739. [Class 97 (i)] A spectacle lens providing correction for ordinary refractiye errors, and also providing for a change in magnification without change of focus to correct " size error " of the optical image consists of two coaxial components which in combination correct both forms of error, although neither of the components is designed to correct only one of the errors, the two components being fitted and secured together adjacent their peripheries to produce a unitary lens structure. The lens shown in Fig. II has two components 1, 2 separated by an annular spacer member 11 of soft glass &c. so as to provide four refractive surfaces. The components, with the spacer, are mounted between rotating supports 5, 6 and a blowpipe flame 9 is applied to the edges so that they are fused together. The spacer member may extend over the whole space between the lens components. In a modification, the inner surfaces of the components have the same curvature and are placed in contact so that the composite lens has only two refractive surfaces. In another modification in which the inner surfaces are dissimilar and enclose an air space, the edges of the lenses are so shaped that they will butt together. Specification 412,081 is referred to.