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US 4,362,365 AGranted
Achromatic microscope objective
AssigneeCarl-Zeiss-Stiftung
InventorKarlheinz Esswein
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AssigneeCarl-Zeiss-Stiftung
InventorKarlheinz Esswein
Estimating the term…
An achromatic microscope objective having three lens components. The first and second components are individual positive lens elements and the third component is a cemented doublet made up of a negative element and a biconvex positive element. The objective is characterized by a particularly advantageous selection of the glasses used for the respective elements. The first or front element has an index of refraction in the range of 1.55 to 1.70 and an Abbe number in the range of 45 to 68; the second element has these same ranges; the third element (negative element of the doublet) has an index of refraction in the range of 1.65 to 1.97 and an Abbe number in the range of 20 to 40; and the fourth element (positive element of the doublet) has an index of refraction in the range of 1.46 to 1.57 and an Abbe number in the range of 50 to 85. By using glasses having these characteristics, it is possible to produce at modest expense a microscope objective with very good correction of all image errors.
An achromatic microscope objective with a magnification within the range of 35.times. and 45.times. and a numerical aperture greater than 0.60, the complete objective having only four lens elements forming three lens components, the first component, numbering the components consecutively from front to rear, being a single positive element, the second component also being a single positive element, and the third component being a cemented doublet consisting of a front negative element and a rear biconvex positive element, the refractive index n.sub.d and the Abbe number v.sub.d of each element being within the range indicated in the following table:
Dependencies are inferred from the claim text.