RU2393515C1 - Lens with remote input pupil - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: first is single positive lens. Second is negative meniscus with concavity facing the object and made up of negative and positive lenses glued together. Third is positive meniscus with its concavity facing the object. Fourth is positive made up of two single lenses, first being lenticular lens and second being positive meniscus with its concavity facing the image. Fifth is negative meniscus with its concavity facing the image and being made up of lenticular lens and biconcave lens.

EFFECT: increased distance from input pupil to first surface of lens and better quality of image.

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Description

The invention relates to optical instrumentation, and in particular to lenses with a remote entrance pupil, and can be used in observation devices and television viewing complexes.

A lens is known that contains five components, the first of which is a single positive lens, the second is a biconcave lens, the third is a positive meniscus facing concavity to the object, the fourth is a positive lens glued from a biconvex and meniscus lenses, and the fifth is a single negative meniscus convex to the subject. The entrance pupil of the lens is located near the first surface of the first component (US Patent No. 4464024, CL G02B 9/60, 1984).

The specified lens has a small relative aperture, which prevents the construction on its basis of the optical system of a television complex operating in twilight lighting conditions. In addition, the absence of a pupil does not allow placing in front of the lens the dimming device necessary to maintain a constant level of image illumination.

Closest to the claimed is a lens with a remote entrance pupil containing five components, the first of which is positive, made in the form of a double-glued lens, the second is a biconcave lens, the third is a positive meniscus facing concavity to the object, the fourth is positive, made in the form of a single a biconvex lens, the fifth is a positive meniscus facing concavity to the image, glued from a biconvex and biconcave lens. The entrance pupil of the lens is 0.5 mm relative to the first surface of the first component (RF Patent No. 2053530, IPC ⁶ G02B 9/60, 1993).

The specified lens has a focal length of the lens F ₀ = 14 mm, the relative aperture D ₀ / F ₀ = 1: 1.4 and the angular field 2W = 43 °. The lens is achromatized in the wavelength range Δλ = 450 ÷ 750 nm. At the spatial frequency ν = 80 mm ^-1, the contrast transfer coefficient is equal to: in the center of the angular field T _C (ν) = 0.5; in the zone of 0.8 of the angular field (2W = 35 °) T _K (ν) = 0.2. The distortion in the zone of 0.8 of the angular field is equal to δ = 5%.

The disadvantage of this lens is the small distance from the entrance pupil to the first surface of the lens, which does not allow placing a device for controlling the light beam near the entrance pupil, for example, a shutter, a modulator, a scanner, a prism for image rotation, etc.

Since the light beam has the minimum dimensions in the cross section in the plane of the entrance pupil, the placement of such a device near the entrance pupil ensures its minimum dimensions and, accordingly, the minimum dimensions of the entire optical system. When constructing an optical system, it is precisely the dimensions that often serve as an obstacle to the use of such devices.

In addition, the specified lens has insufficient image quality. High-resolution lenses with a resolution of at least 120 mm ^-1 , which this lens does not provide, are often required for television surveillance systems.

The objective of the present invention is to increase the distance from the entrance pupil to the first surface of the lens and improve image quality.

To solve the problem, in a lens with an external entrance pupil containing an aperture diaphragm and five components, the first of which is positive, the second is negative, the third is a positive meniscus facing concavity to the object, the fourth is positive, containing a single biconvex lens, and the fifth is a meniscus facing concavity to the image, glued from a biconvex and biconcave lenses, new is that the first component is made in the form of a single lens, the second component is made in the form of a meniscus, ar Tightened with concavity to the object, glued from negative and positive lenses, the fourth component is made in the form of two single lenses, the first of which is biconvex, the second is the positive meniscus facing the concavity to the image, the fifth component is made negative.

In a particular case, in the lens with a remote entrance pupil, the following relations are satisfied:

0.5 · F ₀ <S ₀ <1.5 · F ₀ ;

0.9 F ₀ <F ₄ <1.4 F ₀ ;

where S ₀ is the distance from the aperture diaphragm to the first surface of the first component;

F ₄ is the focal length of the fourth component;

F ₀ is the focal length of the lens.

The presented design allows you to increase the distance from the entrance pupil to the first surface of the lens and improve image quality.

In the particular case, these ratios determine the requirements for the design parameters of the lens, which allows for simultaneous large removal of the entrance pupil and high image quality.

Increasing the distance from the entrance pupil to the first surface of the lens allows you to place near the entrance pupil a device for controlling the light beam, for example, a shutter, a modulator, a scanner, a prism for image rotation, etc.

Figure 1 shows the optical scheme of the lens, figure 2 is the calculated transmission coefficient of the contrast of the lens.

The lens consists of sequentially placed on the optical axis of the aperture diaphragm 1 and five optical components. The first component is positive, made in the form of a single lens 2. The second component is a negative meniscus facing concavity to the object, made from a negative lens 3 and positive lens 4. The third component is a single positive meniscus 5 facing concavity to the object. The fourth component is positive, made in the form of two single lenses 6 and 7, the first of which is biconvex, the second is a positive meniscus, facing a concavity to the image. The fifth component is the negative meniscus, facing concavity to the image, glued from a biconvex lens 8 and a biconcave lens 9.

In the particular case, the following relations are satisfied:

0.5 · F ₀ <S ₀ <1.5 · F ₀ ;

0.9 F ₀ <F ₄ <1.4 F ₀ ;

where S ₀ is the distance from the aperture diaphragm to the first surface of the first component;

F ₄ is the focal length of the fourth component;

F ₀ is the focal length of the lens.

The following is an example of a specific implementation of the lens with a remote entrance pupil. The table shows the design parameters of the lens - the radii of the surfaces, the thickness of the lenses and the air gaps between them, the light and full diameters and brands of lens glasses.

Table No. Radii, R, mm Thickness, T, mm Light diameters, D _CB , mm Full diameters, D _P , mm Glass mark one 34.83 four 17.6 22 STK19 2 1, E + 08 6.5 17.6 22 3 -14.06 2.5 17.8 22 TF10 four -40.55 4,5 20,0 26 FC11 5 -21.68 0.2 20,2 26 6 -40.55 6.0 20,4 28 STK19 7 -23.77 0.2 25.8 28 8 40.55 6.0 26.0 28 FC11 9 -54.45 0.2 25.6 28 10 19,409 5.5 22.4 26 STK19 eleven 48.75 0.2 19.6 26 12 14,454 5.5 17.0 19 FC11 13 -40.55 1,5 14.0 19 TF10 fourteen 9,036 4,5 10,2 eleven

The aperture diaphragm is placed at a distance S ₀ = 24 mm from the first surface of the lens. The diameter of the aperture diaphragm is D ₀ = 12.9 mm.

In order to reduce the complexity of manufacturing in this design, four surfaces with the same radii of curvature (R ₄ = R ₆ = R ₈ = R ₁₃ ) were used, and, in addition, one flat surface was used (R ₂ = ∞).

The lens has the following characteristics:

- focal length F ₀ = 18.1 mm;

- relative aperture D ₀ / F ₀ = 1: 1.4;

- angular field of view 2W = 26 ° (linear field 2Y = 8.2 mm);

- wavelength range Δλ = 450 ÷ 650 nm,

- distortion at the edge of the field δ = 2.8%.

Correction of lens aberrations provides a high contrast transfer coefficient within the entire angular field. At the spatial frequency ν ₁ = 80 mm ^-1, the contrast transfer coefficient is equal to: in the center of the angular field T _C (ν ₁ ) = 0.6; on the edge of the angular field T _K (ν ₁ ) = 0.3. Accordingly, at the spatial frequency ν ₂ = 120 mm ^-1, the contrast transfer coefficient is equal to: in the center of the angular field T _C (ν ₂ ) = 0.4; on the edge of the angular field T _K (ν ₂ ) = 0.15.

The positive effect of the proposed lens design is that it provides, in comparison with the prototype, improved image quality and increased distance from the entrance pupil to the first surface of the lens. Increasing the removal of the entrance pupil makes it possible to use the lens in conjunction with a device for controlling the light beam, for example, a shutter, a modulator, a scanner, a prism for image rotation, etc.

Claims (2)

1. A lens with a remote entrance pupil containing an aperture diaphragm and five components, the first of which is positive, the second is negative, the third is a positive meniscus facing concavity to the object, the fourth is positive, containing a single biconvex lens, the fifth is the meniscus facing concavity to an image glued from a biconvex and biconcave lens, characterized in that the first component is made in the form of a single lens, the second component is made in the form of a meniscus, facing concavity to the object, sk len from negative and positive lenses, the fourth component is made in the form of two single lenses, the first of which is biconvex, the second is the positive meniscus facing the concavity to the image, the fifth component is made negative. 2. The lens according to claim 1, characterized in that for S ₀ - the distance from the aperture diaphragm to the first surface of the first component, F ₄ - the focal length of the fourth component, and F ₀ - the focal length of the lens, the relations
0.5 · F ₀ <S ₀ <1.5 · F ₀ ; 0.9F ₀ <F ₄ <1.4F ₀

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