Importance

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Abstract

Objective lenses (e.g., for microscopy), and adapters for such lenses, are disclosed providing adjustability of the amount of spherical aberration imparted to an image by an objective lens due to variations in cover glass thickness. The adapter can be axially inserted imagewise of the objective lens, or between a first objective lens and a second objective lens of an objective lens system. The adapter comprises an axially movable lens group comprising a cemented lens including a negative lens and a positive lens and a cemented surface having negative refractive power. Spherical aberration of the objective lens is adjusted by axially moving the movable lens group. Where r.sub.1 is the curvature radius of the cemented surface, n.sub.P is the refractive index of the positive lens, n.sub.N is the refractive index of the negative lens, the lens satisfies the condition .vertline.(n.sub.N -n.sub.P)/r.sub.1 .vertline.<0.3.

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First Claim