SU200806A1 - - Google Patents

Description

FOUR-LINE APOCHROMATIC LENS

The known lenses used, for example, in stereoscopic microscopes, containing a negative meniscus facing the lens in concavity, a single positive lens, a negative meniscus opposed to the image concavity, and a positive lens, have an insufficiently corrected secondary spectrum and spherochromatic aberration.

The proposed lens differs from the well-known fact that a negative meniscus of glass, the difference between the Abbe number and the partial relative dispersion of which with the same material values of positive lenses in the module does not exceed 40-50 and 0.004-0, 005 units, respectively, facing concavity to the image , and a positive lens, for example, from fluorite, is made pasted-on, with the radii of curvature of their adjacent surfaces set in the order of 0.3-0.4 times the focal length of the lens and their ratio does not exceed 1.03, and the negative meniscus, facing the concavity of the lens, and a single lens made of flint and fluorite, respectively. This makes it possible to correct the secondary spectrum and spherochromatic aberration.

The lens consists of four single lenses 1,2,3 and 4, separated from each other by small air gaps. Lens / - negative meniscus convex to the image; the absolute value of the onic force of the meniscus is 2-2.5 times less than the optical power f of the objective; the meniscus thickness is (0.2-0.3) /, where / is the focal length of the lens; radii of curvature of the surfaces r P (0.5 - 0.6) /, g. - (0.4 0.5) /, refractive index of glass ip 1,, 7, Abbe number VD 30-f-40.

Lens 3 is a negative meniscus, facing its concavity to the image, with an optical power in absolute value equal to (0.5–0.8) f.

Each of the 2 v lenses (4 are two-convex positive lenses; the optical powers f2 and f4 of these lenses are determined

0

inequality:

but overall optical,

-four

eka force (pho + f) (1.8 + 2.2) f. Both lenses 2 {4 are made of a material with an Abbe coefficient of 95, which has an unusual course of partial relative dispersion (for example, fluorite); the magnitude of the quotient is different from its magnitude in glass, from which lens 3 is made, no more than by 0.004-0.005, while VD exceeds its magnitude in glass by 40-50 units. The radii of curvature of the adjacent surface lenses 5 and 4 are the same in sign and differ in magnitude (1 3) o / o; rear focal length of the lens Sp,; 1.1 /.

Subject invention

A four-lens anochromatic lens containing a negative meniscus facing the concavity of the lens, a single positive lens, a negative meniscus facing the concavity of the image, and a positive lens that differs

the fact that, in order to correct the secondary spectrum and spherochromatic aberration, the negative meniscus from glass, the difference between the Abbe number and the partial relative dispersion of which with the same material values of positive lenses does not exceed 40-50 and 0.004-0.005 units, respectively, turned to image, and a positive lens, for example, from

fluorite, are made pasted-on, with the radii of curvature of their adjacent surfaces being set to the norm of 0.3-0.4 magnitudes of the focal length of the objective and their ratio does not exceed 1.03, and the negative meniscus,

facing the concavity of the lens, and a single lens made of flint and fluorite, respectively.

3 "