RU2260825C1 - Objective - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: the objective consists of successively located on the optical axis first component including a positive meniscus turned by the convexity to the object, double-glued meniscus containing a biconvex and biconcave lenses, and a negative meniscus turned by the convexity to the object, and the second component consisting of a single biconvex lens. The focal powers of the components relate as 3.5 ≤ f^{`</sup> <sub>1comp</sub>/ f<sup>`} _2comp ≤ 4, where f^{`</sup> <sub>1comp</sub>, f<sup>`} _2comp - the focal lengths of the first and second components. The effective distance between the components equals 0.2 ≤ d_eff.comp ≤ 0.22, where d_eff.comp= d_comp /f^`,d_comp- the distance between the components, f- objective focal length.

EFFECT: provided an increase of the field of vision, and enhanced quality of image due to the reduced spherical aberration, meridian curvature and sagittal curvature.

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Description

The invention relates to optical instrumentation and can be used in television surveillance systems.

Known lenses according to copyright certificates of the USSR No. 1236412, IPC G 02 B 9/34, 9/50, 1984, No. 1446585, IPC G 02 B 9/34, 1988, according to patent RU No. 2175774, IPC G 02 B 13/14, 9/34, 11/20, 2000. Lenses according to USSR copyright certificates No. 1236412 and No. 1446585 have a small relative aperture, and the lens according to RU patent No. 2175774 has a small angular field.

The closest analogue is the lens for the infrared spectrum according to patent RU No. 2072733, IPC G 02 B 13/14, 9/34, 1994, made in the form of two components. The first component consists of a positive meniscus convex to the object and a double-glued meniscus consisting of biconvex and biconcave lenses. The second component consists of a negative meniscus convex to the object and a biconvex lens. However, it has a small field of view angle and poor image quality due to insufficient correction of axial and field aberrations.

The objective of the invention is to provide a lens with enhanced performance.

The technical result achieved by the implementation of the invention is an increase in the angle of the field of view with higher image quality achieved by reducing spherical aberration, meridional curvature and sagittal curvature.

This is achieved by the fact that in a lens made of two components and consisting of a positive meniscus convex to the object sequentially located on the optical axis, a double-glued meniscus containing a biconvex and biconcave lens, a negative meniscus convex to the object and a single biconvex lens, and unlike the known, the first three lenses form the first component, namely the positive meniscus, the double-glued meniscus and the negative meniscus, and the second component consists of a biconvex lens, while the optical powers of the components are correlated as

3,5≤f ' _1comp / f' _2comp ≤4,

where f ' _1komp - the focal length of the first component, mm;

f ' _2komp - the focal length of the second component, mm,

and the reduced distance between the components is

0.2≤d _priv.comp ≤0.22,

where d _priv.comp = d _comp / f ',

d _comp - the distance between the components, mm,

f 'is the focal length of the lens, mm

The invention is illustrated by drawings: in Fig. 1, an optical diagram of a lens is shown, in Fig. 2 is a graph of longitudinal spherical aberration, in Fig. 3 is a graph of curvature and distortion, in Fig. 4 is a graph of polychromatic modulation transmission coefficient (KPM).

The lens (Fig. 1) contains two components, the first of which consists of a positive meniscus 1 convex to the object, a double-glued meniscus consisting of a biconvex lens 2 and a biconcave lens 3, and a negative meniscus 4, convex to the object, and the second component - biconvex lens 5.

The lens works as follows: the light from an object located at an infinitely large distance from the first component, refracting, passes through lenses 1, 2, 3, 4, 5 and forms an image of the object in the focal plane of the lens.

In accordance with the proposed technical solution, the lens variant for the focal length f '= 24.97 mm is calculated, the design parameters of which are given in the table.

Radii, mm Thickness mm Glass mark 20.56 3,5 TK21 1432.2 0.2 10,399 4.4 TK21 -123.88 2 TF5 13.49 1,5 23,99 2 TF5 5,834 5.2 8.67 3,5 LF5 -478.6

The lens has a field of view angle of 2ω = 18 °, a relative aperture of 1: 1.8 and high image quality:

- spherical aberration on the pupil area m = 0.707 ΔS '= - 0.03 mm (figure 2),

- meridional curvature ΔX'm = -0.001 mm (figure 3),

- sagittal curvature ΔX's = -0.018 mm (figure 3).

The polychromatic modulation transmission coefficient in the image of the sinusoidal world of absolute contrast at the spatial frequency N = 30 mm ^-1 (Fig. 4) in the spectral range of wavelengths from 450 to 650 nm is

1) for the axial point of the subject -0.83,

2) for the field ω = 9 °:

the meridional section is 0.72,

sagittal section - 0.74.

The ratio of the focal lengths of the components:

3,5≤f ' _1comp / f' _2comp = 54,45 / 14,76 = 3,69≤4,

and the reduced distance between the components:

0.2≤d _priv.comp ≤d _comp / f '= 5.2 / 24.97 = 0.208≤0.22.

The closest analogue:

- spherical aberration in the area m = 0.707 of the pupil ΔS '= - 0.08 mm,

- meridional curvature ΔX'm = 0.05 mm,

- sagittal curvature ΔX'm = -0.14 mm.

Moreover, the ratio of the focal lengths of the components is equal to:

f ' _1comp / f' _2comp = 90.25 / 521.65 = 0.173,

where f ' _1komp - the focal length of the first component, mm,

f ' _2komp - the focal length of the second component, mm

In this case, the reduced distance between the components is

d _{priv.comp =} d _comp / f '= 18/85 = 0.212,

where d _comp - the distance between the components, mm,

f 'is the focal length of the lens, mm

As can be seen from a specific calculation example, a lens made with the same lenses as the description and location along the beam throughout the lens, with the same reduced distance between the components, but with a different component structure (analogue: first component - 2 lenses, the second component has 2 lenses, the proposed lens: the first component has 3 lenses, the second component has 1 lens) and with a different ratio of their optical powers has higher performance characteristics, which indicates the fact that the proposed set of distinctive features provides the desired result.

Thus, a lens with a high image quality, reduced spherical aberration, meridional and sagittal curvature is obtained.

Claims (1)

A lens made of two components consists of a positively aligned meniscus convex to the object sequentially located on the optical axis, a double-glued meniscus containing a biconvex and biconcave lens, a negative meniscus convex to the object, and a single biconvex lens, characterized in that the first component forms the first three lenses, namely: the positive meniscus, the double-glued meniscus and the negative meniscus, and the second component consists of a single biconvex lens, pr This forces optical components correspond as

Where

- focal length of the first component, mm;

- focal length of the second component, mm; and the reduced distance between the components is 0.2≤d _priv.comp ≤0.22, where d _priv.comp = d _comp / f '; d _comp - the distance between the components; f 'is the focal length of the lens, mm

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