A new or improved method and device for measuring the vertex power of lenses

摘要

207,045. Reid, R. C. Nov. 27, 1922. Spectacle lenses.-Lenses for measuring by neutralization the back vertex powers of spectacle lenses are made with the contacting portion of such small dimensions in comparison w i t h t h e dimensions of spectacle lenses that the front surface may be placed in contact, or approximately so, with the back surface of a spectacle lens. Fig. 3 shows two examples with the neutralizing lens b surrounded by a concavoconvex portion c preferably with parallel surfaces.