DD240612A1 - THREE-LOW, VIGNETIC-FREE, LOBBY-LIKE OBJECTIVE - Google Patents

Abstract

The invention relates to a tripartite, vignetting-free, long-focal-length objective and can be used for imaging on CCD receivers, television receiving tubes or film material. The task of achieving a relative aperture of 1: 2.8, an angle of view of 9.4, uniformly good correction over the entire image field, almost complete correction of the Gaussian error and reduction of the secondary spectrum is achieved by the presence of three cemented elements, wherein the Gaussian error is almost eliminated by the Kittflaeche of the first Kittgliedes and by using CaF2 or a similar glass in the second Kittglied the secondary spectrum is reduced. Fig. 1

Description

Objective of the relative aperture 1: 2 and DE-OS 2611105 describe a six-lens objective for a relative opening 1: 2.

These lenses have the disadvantage that they are not Vignettierungsfrei and thereby from the center to the edge of the image for

certain imaging tasks cause a strong drop in illuminance.

Another disadvantage is that these lenses are cast-faulty. The blue spectral range (g-ünie) is opposite

strongly overcorrected in the red spectral region (C 'line).

The known lenses have a value of the secondary spectrum due to the glasses used for certain

Imaging tasks can be annoying. DE-AS 2322813 describes a five lens lens with almost completely corrected

secondary spectrum, but has only a relative aperture of 1: 4.8 and is not vignetting free.

Object of the invention

The aim of the invention is a lens that is vignetting free at a relatively short length.

Explanation of the essence of the invention

The invention has for its object to provide a lens that has a relative aperture of 1: 2.8, for a viewing angle of about 9.4 ° evenly corrected for the entire image field is corrected in which the Gaussian error and the secondary spectrum over conventional lenses is reduced.

This object is achieved by a three-membered, vignette-free, long focal length objective characterized in that on the optical axis successively concentric to the aperture diaphragm positive cemented member whose cemented surface is concentric to the aperture diaphragm, concentric to the aperture diaphragm negative cemented member whose cemented surface is concentric to the object plane, an aperture diaphragm and a to the image plane concentric positive cemented member, the cemented surface is concentric with the aperture diaphragm, are arranged. The Gaussian error is almost completely eliminated by the effect of the cemented surface in the first cemented element, whereby the following conditions apply:

Γ3>Γ,> Γ ₂ > 0 (1)

[n _e i - n _e2 | <0.01 (2)

V ₁ > V ₂ (3)

V ₂ > 40 (5) '

The objective according to the invention is distinguished by a reduced secondary spectrum, which is achieved by using fluorspar or a glass fiber-like glass in the positive lens of the second cemented element by the substantial divergent partial dispersions of conventional glasses, in which:

V ₃ > 80 (5)

ΔΡ ₉ _Ρ3> 0.025 (6)

Furthermore, the second cemented element satisfies the conditions

r ₄ > r ₆ > 0. (7)

r ₅ <0 (8)

d ₃ + d ₄ > 0.15f (9)

V ₄ <35 (10)

The third cemented member effects through the use of more dispersive glasses in the positive lens than in the negative lens

V ₅ <v ₆ , (11)

r ₉ > r ₇ > 0 (12)

r _s <0 (13)

in conjunction with the first and second cemented members, the correction of the color magnification error.

The objective according to the invention can be manufactured with such lens diameters that the light bundle can be up to a

Image angle of 2τ =. 9.4 ° is limited only by the aperture and the lens vignette is free.

By adhering to the condition

d! + d ₂ + I ₁ + d ₃ + d ₄ + I ₂ + d ₅ + d ₆ + s' _F · <1.05f (14)

it is achieved that the distance from the first surface to the image-side focal point is not much larger than the focal length.

In addition to the magnification β = 1 / <»the lens also has a very good correction state up to magnification β = -1/20.

embodiments

The invention will be explained in more detail by way of examples. 1 shows the lens sectional image of the objective according to the invention

FIG. 2: the transverse aberrations Ay'in dependence on the aperture at different image angles δ for β = 1 / °° FIG. 3: the spherochromatic longitudinal deviations As' as a function of the aperture A for the wavelengths e, g and C for

β = 1 / oo

4: the distortion as a function of the angle of view δ for β- 1 / °° FIG. 5: the spherochromatic longitudinal deviations As'in dependence on the aperture A for the wavelengths e, g, and C for

β = -1/20 and FIG. 6 the distortion as a function of the angle of view δ for j3 = -1/20.

In Fig. 1 are successively arranged along the optical axis 0-0 ': to the aperture diaphragm B concentric positive Kittglied K ₁ , consisting of the lenses L ₁ , L ₂ , a concentric to the aperture diaphragm B Kitt member K ₂ , consisting of the lenses L ₃ , L ₄ , an aperture diaphragm B, a positive Kittglied K ₃ concentric to the image plane BE, consisting of the lenses L ₅ and L ₆ . The lenses and air gaps are characterized by the corresponding parameters. Possible embodiments are to be represented in the examples on the basis of design data in tabular form.

example 1

f '= 1.0 k = 2.8 2δ = 9.4 ° 53.3 radii thick distances 46.7 r ·, = +0.5289 d, = 0.0207 1.69649 r ₂ = + 0.2187 d _{1 =} 0.1346 1.70065 90.3 r ₃ = +9.9237 l = 0.0010 U = +0.3214 27.5 d ₃ = 0.1082 1.45223 APg_ _F = 0.0366 r _B = -1.9893 d ₄ = 0.1243 1.74707 28.1 r ₆ = +0.2234 I ₂ = 0.0518 + 0.2237 46.7 X ₁ = +0.6537 d _B = 0.0427 1.73430 r ₈ = -1.2337 d ₆ = 0.0207 1.62690 r ₉ = + 2.5497

Example 2

f = 1.0 k = 2.8 radii thick distances r, = +0.4674 d! = 0.0207 r ₂ = +0.2064 d, = 0.1345 r ₃ = +3.3555 l, = 0.0010 r ₄ = + 0.2797 d ₃ = 0.0893 r ₆ = -1.7232 \ d ₄ = 0.0915 T ₆ = +0.1986 I ₂ = 0.0517 + 0.0698 X ₁ = +0.8326 - d ₅ = 0.0724 X ₈ = -0.1733 d * = 0.0103

2δ = 9.4 ° η «

1.69649 1.70065

1.43496 fluorspar

1.74707

1.72794 1.66151

53.3 46.7

94.6 27.5

37.7 50.6

Example 3

f = 1.0 k = 2.8 23 = 9.4 ° radii thick distances r, = +0.4872 d, = 0.0207 1.69649 r ₂ = + 0.2110 Cl ₁ = 0.1346 1.70065 r ₃ = +8.1342 I ₁ = 0.0010 r ₄ = + 0.3026 d ₃ = 0.1183 1.43496 fluorspar r _s = -1.5766 d ₄ = 0.0828 1.74707 r ₆ = + 0.2187 I ₂ = 0.0518 + 0.2418 r ₇ = +0.6862 d ₅ = 0.0444 1.73430 r ₈ = -0.9098 d _e = 0.0207 1.62690 r ₉ = +2,737

53.3 46.7

94.6 27.5

28.1 46.7

For the examples, the radii, thicknesses and spacings may vary up to ± 10%, the refractive indices ± 0.05 and the Abbe's numbers ± 5.

Claims (2)

Claim: 1. A tripartite, vignette-free, long-focal length objective consisting of six lenses, characterized in that the objective consists of three groups of putties, two being concentric with the aperture stop, that the objective is characterized by subsequent design data. (14) 3. Lens according to claim 1 and 2, characterized in that the radii, thicknesses and air distances within ± 10%, the refractive indices ± 0.05 and Abbe's numbers ± 5 are variable. For this 2 pages drawings. Field of application of the invention The invention can be applied to imaging on CCD receivers, television tubes or film material. Characteristic of the known technical solutions For this purpose, objects are known in which the length from the first surface to the image-side focal point is approximately equal to or smaller than the focal length. U.S. Patent No. 4,057,330 describes a five-lens lens for a relative aperture of 1: 2.8, while DE-OS 2632461 discloses a five-lensed lens