RU2316795C1 - Two-lens objective - Google Patents

Abstract

FIELD: optical instrument engineering.

SUBSTANCE: two-lens objective can be used in different optical systems as in visual and in IR-systems. Objective has first lens made in form of biconvex one, and second lens made in form of negative meniscus turned with its convexity to image. Lenses are made of optical glass being transparent in visible and near IR spectrum range. Radiuses of biconvex lens are equal in absolute value. Relation of first radius being disposed on path of beams of menisci lens to its second radius is shorter than 0,8. Relations are met as 1,46<n₁<1,63; 1,66<n₂<1,78 where n₁ and n₂ rare refractivity factors of material of first and second lenses along beam paths. Lenses can be single ones or glued ones.

EFFECT: simplified design; improved manufacturability; increased focal length; higher quality of image.

Description

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

A well-known two-lens bonded lens (“Applied Optics.” I.A. Turygin, Moscow, “Mechanical Engineering”, 1966, p. 423). It consists of a glued biconvex lens and a negative meniscus convex to the image along the ray. The lens has a small focal length of 100 mm and lack of manufacturability, as It requires the use of different test glasses and a different processing tool for each optical surface.

The closest analogue to the claimed technical solution is a two-lens lens - achromat (French Application No. 2025476, class G02B 13/00, 5/00, publ. 1970), operating in the infrared range from 8 to 14 microns, consisting of individual biconvex lens and negative meniscus convex to the image. The lenses of the lens are made of CsBr and ZnS materials with refractive indices of 1.66251 and 2.1986. In addition, the ratio of the first radius along the rays of the second lens to its second radius is 0.858. This lens has a focal length of 100 mm, and it has insufficient adaptability, as It requires the use of different test glasses and a different processing tool for each optical surface.

The task of the invention is the creation of a technologically advanced two-lens lens with enhanced performance characteristics.

EFFECT: simplified design and improved manufacturability with increased focal length and high image quality.

This is achieved by the fact that in a two-lens lens, consisting of a biconvex lens located along the beam and a negative meniscus convex to the image, in contrast to the known one, both lenses are made of optical glass transparent in the visible and near infrared spectral regions, the biconvex radii the lenses are equal in absolute value, the ratio of the first along the rays of the radius of the meniscus lens to its second radius is less than 0.8, and there are relations:

1.46 <n ₁ <1.63;

1.66 <n ₂ <1.78;

where n ₁ is the refractive index of the material of the first lens along the rays;

n ₂ is the refractive index of the material of the second lens along the rays.

In addition, in a two-lens lens, the lenses can be glued.

Figure 1 presents the optical scheme of the proposed lens with glued lenses, and figure 2 with single.

A two-lens lens (FIG. 1 and FIG. 2) consists of a biconvex lens 1 and a negative meniscus 2 located along the beam, convex to the image. Lenses 1 and 2, made of optical glass, transparent in the visible and near infrared region of the spectrum, can be single (figure 1) and glued (figure 2). The radii of the biconvex lens 1 are equal in absolute value, and the ratio of the first along the rays of the radius of the meniscus lens 2 to its second radius is less than 0.8.

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

In accordance with the proposed solution, two two-lens lenses are designed.

The first lens is made of single lenses and fixed for λ = 1060 nm and for λ = 656.28 nm. The lens can work as a collimator. The lens operates in the visible and near infrared spectral range.

The design parameters of the first lens are given in table 1.

The entrance pupil coincides with the first optical surface, but may be in another place.

Characteristics of the calculated first lens:

focal length 150.75 mm relative hole 1: 4.7 field of view angle 2 deg. 8 minutes

The lens has the following aberrations for λ = 1060 nm:

transverse spherical aberration for a point on the axis no more than 0,0005 mm lateral aberration of wide inclined beam in the meridional section for the field view 2W = 2 deg. 8 min no more than 0,0275 mm lateral aberration of wide inclined beam in a sagittal section for the field view 2W = 2 deg. 8 min no more than 0,0057 mm meridional astigmatic segment X _m no more than 0.109 mm sagittal astigmatic segment X _s no more than 0,048 mm distortion no more than 0,0009%

In the present invention:

R ₁ = | R ₂ | = 75.505;

n ₁ = 1.615192;

n ₂ = 1.761712;

where R ₁ is the radius of the first along the rays of the optical surface of the biconvex lens;

R ₂ is the radius of the second along the rays of the optical surface of the biconvex lens;

n ₁ is the refractive index of the material of the first lens;

n ₂ is the refractive index of the material of the second lens.

In addition, the ratio of the first radius along the rays of the meniscus lens to its second radius along the rays is 0.065.

The second lens is glued, fixed in the spectral range from 480 nm to 660 nm and can also work as a collimator. The lens operates in the visible range of the spectrum.

The design parameters of the second lens are given in table 2.

The entrance pupil is located at a distance of 60 mm in front of the first optical surface of the second lens, but can be located in another place.

Characteristics of the calculated second lens:

focal length 399.55 mm relative hole 1: 6.9 field of view angle 12 deg.

The lens has the following aberrations for λ = 546 nm:

transverse spherical aberration for a point on the axis no more than 0,012 mm lateral aberration of wide inclined beam in the meridional section for the field view 2W = 12 deg. no more than 0,095 mm lateral aberration of wide inclined beam in a sagittal section for the field view 2W = 12 deg. no more than 0,03 mm meridional astigmatic segment X _m no more than 9.48 mm sagittal astigmatic segment X _s not more than 4.24 mm distortion no more than 0.3%

In the present invention:

R ₁ = | R ₂ | = 193.634;

n ₁ = 1.518294;

n ₂ = 1,677617;

where R ₁ is the radius of the first along the rays of the optical surface of the biconvex lens;

R ₂ is the radius of the second along the rays of the optical surface of the biconvex lens;

n ₁ is the refractive index of the material of the first lens;

n ₂ is the refractive index of the material of the second lens.

In addition, the ratio of the first radius along the rays of the meniscus lens to its second radius along the rays is 0.186.

Thus, as a result of the proposed solution, a technical result is obtained: a two-lens lens with increased manufacturability with high image quality with increased focal length and with a simple design is created.

Claims (2)

1. A two-lens lens, consisting of a biconvex lens located along the beam and a negative meniscus convex to the image, characterized in that both lenses are made of optical glass transparent in the visible and near infrared spectral regions, the radii of the biconvex lens are equal in absolute value , the ratio of the first along the rays of the radius of the meniscus lens to its second radius is less than 0.8 and the relations 1.46 <n ₁ <1.63, 1.66 <n ₂ <1.78, where n ₁ is the refractive index of the material of the first lens along the rays; n ₂ is the refractive index of the material of the second lens along the rays. 2. The two-lens lens according to claim 1, characterized in that the lenses are glued.

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