RU1775706C - Planachromatic microscope objective lens - Google Patents

Abstract

The invention relates to optical instrumentation The essence of the invention: the lens contains two negative meniscus, facing concavity to the object, between which there is a flat convex lens, while the first negative meniscus and flat convex lens are made of glass with a refractive index of not more than 1.5 and an average dispersion coefficient of not less than 68. and the second negative meniscus is made of glass with a refractive index of at least 1.75 and an average dispersion coefficient of not more than 28 2 yl

Description

The invention relates to optical instrumentation, namely to planachromatic lenses of microscopes

A known microscope lens, consisting of a plano-convex frontal lens, a single positive lens, the focal length of which is 18-22 of the focal length of the entire lens, and a double-glued positive lens, a meniscus with a frontal magnification equal to 1x, with its concave surface facing the space of objects, and the thickness is 0.2 of its focal length

As a prototype, a microscope lens was selected containing two negative menisci facing concavity to the object, between which there is a positive lens

But the specified lens does not provide the required image quality

The essence of the invention lies in the fact that the planachromatic microscope objective, containing two negative menisci facing the object, between which the positive lens is located, the positive lens is made convex, while the first negative meniscus and the convex lens are made of glass with a refractive index of not more than 1 5 and an average dispersion coefficient of at least 68, and the second negative meniscus is made of glass with a refractive index of at least 1.75 and an average dispersion coefficient no more than 28

The main objective in the development of this lens is to improve image quality while increasing the magnification. The positive lens is made convex and corrects for spherical aberration

s

M | SL XI

about

higher order for a point on the axis, as well as image curvature and astigmatism.

I will examine the presence of glasses in GOST 13659-78, I came to the conclusion that the first negative meniscus and flat convex lens are made of glass with a refractive index of not more than 1.5 and the average dispersion coefficient of not less than 68, and the second negative meniscus is made of glass with a refractive index of not less than 1.75 and an average dispersion coefficient of not more than 28, for correcting chromatic aberration, especially chromaticity magnification, as well as image curvature and astigmatism.

In FIG. 1 is an optical diagram of a planochromatic microscope objective, where 1 is the first negative meniscus facing concavity to the space of objects, 2 is a positive plano-convex lens, 3 is the second negative meniscus facing concavity to the space of objects; in FIG. 2 presents graphs of its aberrations.

A planachromatic microscope objective with the following optical characteristics is presented as a specific example:

increase

front aperture

image size

distance from the plane

items

to the last surface of the lens

tube length

front worker

line segment

This microscope objective is designed for infinity tube length. In the above example, the planachromatic microscope objective has the following aberrations.

The transverse spherical aberration for a point on the axis in the entire spectral range does not exceed 0.011 mm.

Wave aberration for a point on the axis:

/ 5.0x

A 0.12

2u 20.mm

1 30.47 mm infinity

.28mm

Neusoplanasia coefficient: pupil margin - 0.028%, zone - -0.005%

Image curvature and astigmatism are equal:

y - 1.94 mm zt1 - 0.06 mm zs - 0.438 mm y -1.37 mm zt - 0.144 mm zs - 0.246 mm zs -zt1 - 0.378 mm Zs -zt -0.102 mm

Chromatism of magnification together with a tube lens does not exceed 0.16%. The mean square wave aberration over the field in the plane of the best setting is:

At

10

8.66

7.07

5.0 o

twenty

The value of the mean square wave aberration in the spectral range, field and pupil is equal to:

1. Without taking into account the defocus and distortion of 0.059.

2. Without taking into account the defocus, distortion and curvature of the image, 0.059.

Strehl number by field is presented in the following table.

Strehl number

10 8.66 7.07 5.0 O 0.76 0.83 0.87 0.90 0.94

35

Claims (1)

The claims Planachromatic microscope objective containing two negative menisci facing concavity to the object, between which is located a positive lens, characterized in that, in order to improve image quality while increasing the magnification, the positive lens is made plano-convex, while the first negative meniscus and plano-convex lens are made of glass with a refractive index of not more than 1.5 and an average dispersion coefficient of not less than 68, and the second negative meniscus made of glass with a refractive index of not less than 1.75 and a coefficient of average dispersion of not more than 28. Maloshost O. 12 si / 7 U -to. o w AS -i.o o f.o z} -to o 0.1% -f.o o to kg W. FIG. 1 fo.t / D12 sin Lt V fa y 2k jfr