Objective lenses
First Claim
1. A modified Petzval lens system comprising a front lens group and a rear lens group spaced from the front lens group, wherein the front lens group comprises at least two doublet components one of which consists of a crown positive element cemented to a flint negative element with the flint glass having significantly higher refractive index and dispersion values than those of the crown glass, the other said doublet component consisting of a crown positive element and a flint negative element with the flint and crown glasses having similar refractive indices but dissimilar dispersions, the flint glass having a positive red relative partial dispersion deviant.
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Abstract
The invention provides an objective lens with a front lens group and a rear lens group spaced apart from the front group. The front group comprises at least two doublet components one of which is a crown positive element cemented to a flint negative element which has a higher refractive index and dispersion values than those of the crown glass. The other doublet component of the front group is a crown positive element and a flint negative element in which the flint and crown glasses have similar refractive indices but dissimilar dispersions with the flint glass having a positive red relative partial dispersion deviant.
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Citations
16 Claims
- 1. A modified Petzval lens system comprising a front lens group and a rear lens group spaced from the front lens group, wherein the front lens group comprises at least two doublet components one of which consists of a crown positive element cemented to a flint negative element with the flint glass having significantly higher refractive index and dispersion values than those of the crown glass, the other said doublet component consisting of a crown positive element and a flint negative element with the flint and crown glasses having similar refractive indices but dissimilar dispersions, the flint glass having a positive red relative partial dispersion deviant.
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16. In a modified Petzval lens system having a front group of lens elements comprising a doublet component consisting of a crown positive element cemented to a flint negative element, the flint glass having significantly higher refractive index and dispersion values than the crown glass, the lens further having a rear group of lens elements, the improvement comprising an additional doublet component in the front group of lens elements, said additional doublet component being positioned adjacent the first said doublet component and consisting of a crown positive element and a flint negative element, the flint and crown glasses having similar refractive indices but dissimilar dispersions and the flint glass having a positive red relative partial dispersion deviant.
Specification