| 摘要 |
<p>PURPOSE: To provide a two-focus contact lens with improved comfortableness by specifying the spacing and depth of phase zones in an annular concentric shape and a zone profile. CONSTITUTION: The contact lens CL is composed of a front surface AS and a rear surface PS the a diffraction facet (echelette) E and an edge N are provided on the rear surface PS. The annular concentric zones are with a spacing practically proportional to n<1/2> (n) is a zone order} and the depth of the facet is turned to be less thanλ/2 (whereλis a design wavelength). Then, the profile of the zone is turned not to a conventional simple parabolic shape but to the profile shifted from a parabola calculated from a prescribed arithmetic formula. As a result, foreign matter collecting is reduced, the comfortableness is improved and the contact lens for turning yellow color to two focuses is obtained.</p> |
