RU2763120C1 - Double lens - Google Patents

Abstract

FIELD: optical systems.

SUBSTANCE: lens can be used both in visual optical systems and in IR systems. The lens consists of two single biconvex lenses and a negative meniscus facing the image with a bulge. The radii of a biconvex lens are equal in absolute magnitude. There are the following ratios: 0.3≤|R₁|/f'≤0.48; 0.25≤|R₃|/f'≤0.45; 1.5≤|R₄|/f'≤7; 0.07≤|R₃|/|R₄|<0.8, where R₁, R₃, R₄ are the radii of the first, third, and fourth optical surfaces in the course of the rays; f' is the focal length of the entire lens.

EFFECT: increase in the focal length, the diameter of the entrance pupil and the angular field in the space of objects with high image quality.

1 cl, 1 dwg, 2 tbl

Description

The invention relates to optical instrumentation and can be used in various optical systems, for example, in visual and IR systems.

Known two-lens objective, described in Russian patent No. 2384868, IPC G02B 9/10, 9/14, published 03/20/2010, consisting of a biconvex lens located in the direction of the beam and a negative meniscus facing the convexity of the image, in which there are ratios :

| R ₁ | = | R ₃ |;

| R ₁ | <| R ₂ |;

1.41 <n ₁ <1.619;

1.54 <n ₂ <1.79,

where: R ₁ , R ₂ , R ₃ - the radii of the first, second and third optical surfaces along the rays;

n ₁ , n ₂ are the refractive indices of the material of the first and second lenses along the ray path for line e.

This objective has a not large enough aperture ratio of 1:18 and an insufficiently large angular field of 2W = 1 degree. 40 minutes

The closest analogue to the claimed technical solution is a two-lens objective, described in Russian patent for invention No. 2316795, IPC G02B 9/10, Fig. 1, published on February 10, 2008, consisting of a single biconvex lens located along the rays of the rays and a negative meniscus facing the convexity of the image, moreover, the radii of the biconvex lens are equal in absolute value, the ratio of the first along the rays of the meniscus lens radius to its second radius is less 0.8 and the following ratios take place: 1.46 <n ₁ <1.63;

1.66 <n ₂ <1.78,

where: n ₁ , n ₂ - refractive indices of the material of the first and second lenses along the rays.

For the glued-on version of this lens, the following ratios apply:

| R ₁ | / f '= 0.5009;

| R ₃ | / f '= 0.4685;

| R ₄ | / f '= 7.24;

| R ₃ | / | R ₄ | = 0.0647,

where: R ₁ , R ₃ , R ₄ - the radii of the first, third and fourth optical surfaces along the rays;

f 'is the focal length of the entire lens.

This lens does not have a large enough focal length of 150.75 mm, an insufficiently large entrance pupil diameter of 32 mm, and an insufficiently large angular field of 2W = 2 degrees. 8 minutes

The objective of the claimed invention is to create a technologically advanced two-lens objective with improved performance characteristics.

The technical result is an increase in the focal length, the diameter of the entrance pupil and the angular field in the space of objects with high image quality.

This is achieved by the fact that in a two-lens objective, consisting of a single biconvex lens located along the path of the rays and a negative meniscus facing the convexity of the image, moreover, the radii of the biconvex lens are equal in absolute value, in contrast to the known one, the following relations hold:

0.3≤ | R ₁ | / f'≤0.48;

0.25≤ | R ₃ | / f'≤0.45;

1.5≤ | R ₄ | / f'≤7;

0.07≤ | R ₃ | / | R ₄ | <0.8,

where: R ₁ , R ₃ , R ₄ - the radii of the first, third and fourth optical surfaces along the rays;

f 'is the focal length of the entire lens.

The figure shows the optical scheme of the proposed lens.

A two-lens objective consists of a single biconvex lens 1 and a negative meniscus 2, which is convex towards the image, located along the path of the rays. The radii of the optical surfaces of the biconvex lens 1 are equal in absolute value. In addition, the following ratios take place: 0.3≤ | R ₁ | / f'≤0.48; 0.25≤ | R ₃ | / f'≤0.45; 1.5≤ | R ₄ | / f'≤7; 0.07≤ | R ₃ | / | R ₄ | <0.8, where: R ₁ , R ₃ , R ₄ are the radii of the first, third and fourth optical surfaces along the rays; f 'is the focal length of the entire lens. The entrance pupil is located at a distance of 100 mm from the first optical surface, but it can also be in another place.

The lens works as follows: the luminous flux from an object located at infinity enters the lens, where it passes through the lenses 1, 2 and forms an image of the object in the plane of the best installation in which an optical radiation receiver (not shown) is installed.

A two-lens objective was designed in accordance with the proposed solution. The lens has been corrected for λ = 520 nm and achromatized for 520 nm and 900 nm. The lens can function as a collimator, i.e. in the reverse course of the rays. The lens operates in the visible wavelength range and in the near-infrared range of the spectrum.

Characteristics of the calculated lens:

focal length 1001.95 mm relative aperture 1: 16.69 posterior focal segment 955.05 mm angle of view 3 deg. entrance pupil diameter 60 mm

The design parameters of the lens are given in table. one

In the proposed invention:

| R ₁ | = | R ₂ | = 438.5;

0.3 | R ₁ | / f '= 0.4377 0.48;

0.25≤ | R ₃ | / f '= 0.4132≤0.45;

1.5≤ | R ₄ | / f '= 3.13≤7;

0.07≤ | R ₃ | / | R ₄ | = 0.1321 <0.8,

where: R ₁ , R ₂ , R ₃ , R ₄ - the radii of the first, second, third and fourth optical surfaces along the rays;

f 'is the focal length of the entire lens.

Table 2 shows the aberrations of the proposed objective for a wavelength of 520 nm.

Thus, as a result of the proposed solution, a technical result was obtained: a two-lens objective was created with an increased focal length, an entrance pupil diameter and an angular field in the space of objects with high image quality.

Claims (7)

A two-lens objective consisting of a single biconvex lens located along the path of the rays and a negative meniscus facing the image with a convexity, and the radii of the biconvex lens are equal in absolute value, characterized in that the following relations take place: 0.3≤ | R ₁ | / f'≤0.48; 0.25≤ | R ₃ | / f'≤0.45; 1.5≤ | R ₄ | / f'≤7; 0.07≤ | R ₃ | / | R ₄ | <0.8, where R ₁ , R ₃ , R ₄ are the radii of the first, third and fourth optical surfaces along the beams; f 'is the focal length of the entire lens.

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