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Fused bifocal spectacle lenses

A Whitwell



In designing a fused bifocal spectacle lens we have at our disposal three radii which can be varied to satisfy the two conditions, that the distance power and the reading addition have given values, so leaving one degree of freedom.

An expression is found for the convergence of the circles of least confusion of oblique pencils of small aperture; from this, by equating the aberration term to zero, we obtain a quadratic equation the roots of which fix the radius of one surface of the lens subject to the third condition that the circles of least confusion lie on a sphere and so focus on the macula of the eye.


PACS

87.85.J- Biomaterials

42.66.Ct Anatomy and optics of eye

42.79.Bh Lenses, prisms and mirrors

42.70.Ce Glasses, quartz

Subjects

Optics, quantum optics and lasers

Medical physics

Biological physics

Dates

Issue 3 ( 1 January 1930)

Received 20 February 1931



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