DE4102377A1 - Fast lens system for camera - if formed from six lenses with curvatures defined by mathematical formula - Google Patents

Abstract

The invention concerns a fast lens system for a camera. The lens system consists of six lenses with a combined aperture of 1:1.4 and a field of view angle of 38 deg. These lenses, in the image direction, consist of a convergent and a divergent meniscus lens which have their concave sides facing towards the shutter. The system also includes a filter disc and a convergent cemented lens which is constructed from a divergent and a convergent lens placed against each other. In addition there is a convergent lens and a convergent meniscus lens which have their concave sides facing towards the image. The claim also gives mathematical formula for determining the curvature of the lenses depending on their position in the lens system and the focal length of the system. USE - Cameraa.

Description

The objective according to the invention is for imaging tasks CCD receivers, television tubes or film material suitable.

Lenses for this purpose, which are characterized by a high Distinguish the resolution of the picture elements with sufficiently good contrast, are known. However, these lenses have some disadvantages. Either they do not have the required light intensity, do not have a uniform image quality over the entire image field or contain more than six lenses.

From US-PS 46 71 626 is a five lens lens with a Relative opening of 1: 1.73 known. For the required relative Aperture of 1: 1.4 can with this lens type the required Correction of artifacts can no longer be achieved.

Siebenlinsige lenses are from the patents DD 1 60 501 and DD 2 45 059 A1 known. These types of objects have the required relative opening of 1: 1.4, but characterized by the construction seven lenses results in increased production costs and the Lens type according to DD 1 60 501 does not allow a compact design Lens.

In DE 20 57 602 a six-lens objective, consisting of a Condensing lens, a diffusing meniscus lens, a collecting Kittglied, a condenser lens and a collecting meniscus lens exists, for a relative opening of 1: 1 described. This Lens is not for the required field angle of 2σ = 38 °, as it does not match this field angle with the required Correction distinguishes. Cause are those in this Lens field curvature occurring at large field angles and the existing astigmatism.  

The aim of the invention is to overcome the disadvantages of the prior art to eliminate and for the stated application a powerful Develop lens. It should be an economic Be given production.

The invention is based on the object, a fast lens with a relative aperture of 1: 1.4 and a field angle of 2σ = 38 °, which is uniform for the entire image field is well corrected.

According to the invention, this object is achieved in such a lens, that of a collecting and a scattering meniscus lens, whose concave surfaces point towards the aperture stop, the aperture diaphragm, a plane-parallel filter plate, a collecting cemented element, that consists of a diverging lens and a condenser lens composed of a condenser lens and a collecting meniscus lens, whose concave surface is facing the image plane, solved by the following conditional equations to be fulfilled:

-0.02 f '<r₃-r₄-d₂ <0.05 f' (1),
0.45 f '<l₂ + d₃ / n₃ + l₃ <0.80 f' (2),
n₄-n₅ <0.03 (3),
1.73 <(n + + n + + n) / 3 (4),
51.0 <(ν₅ + ν₆ + ν₇) / 3 (5),

in which the symbols have the following meaning:

f '- total focal length,
r _i - radius of the i-th system surface,
d _j - center thickness of the jth element,
l _k - k-th air distance,
n _j - refractive index n _{e of} the jth element
ν _j - Abbe's number ν _{e of} the jth element.

The aperture space is dimensioned so that it incorporates a Filter plate allows.

By this construction according to the invention and the choice of design parameters can the system type known in principle for a larger field of view with balanced correction all aberrations are used. At the same time it was achieved that by the necessary large aperture space for compensates for the use of the filter plate strongly growing aberrations can be achieved and achieved a low distortion becomes.

The collecting cemented element has according to the invention according to condition (3) a small refractive jump on the cemented surface. The radius of the Area to the aperture space is designed so that for the main beam a small angle of incidence and thus a small deflection Due to the refraction on this surface, what happens has a positive effect on the coma correction. Due to the relative strong curved cement surface in combination with the small refractive index jump contributes significantly to the correctability of astigmatism at.

The condenser lens and the collecting meniscus were according to the invention constructed according to condition (4) of high refractive index glass. In Connection with the choice of radii of curvature became a uniform Distribution of the beam deflection on the lens surfaces reached. This leads to the compensation of the conscious of the dissipative Meniscus lens certified residual opening error.

The invention will be explained in more detail with reference to the following drawings become.

Fig. 1 shows the lens sectional image and Fig. 2, 3 and 4 show graphical representations of the Korrektionszustandes of the solution according to the invention.

Fig. 1 shows the lens diagram of the objective according to the invention. Thereafter, the objective consists in the light direction of a collecting meniscus lens L 1 and a scattering meniscus lens L 2 whose concave surfaces to the aperture stop, the aperture B, a plane-parallel filter plate P, a weakly collecting cemented K 1 , consisting of a diverging lens L 3 and a converging lens L 4 , a collecting lens L 5 and a collecting meniscus lens L 6 , the concave surface of the image shows.

The same good correction over the entire field of view is by the described arrangement of the lenses L 1 to L 6 , the filter plate P and the aperture B with the radii r _i , the center thickness d _j , the refractive indices n _e and Abbe numbers ν _e , and The air distances l _k reached, whose values are given in the table to claim 2.

Fig. 2 shows the spärochromatischen longitudinal deviations as a function of the aperture for the wavelengths g and e.

Fig. 3 shows the longitudinal deviations of the sagittal and meridional image surface σ as a function of field angle.

Fig. 4 shows the distortion function of the field angle σ.

Claims (2)

1. A high-power, six-lens objective having a relative aperture of 1: 1.4 and a field angle of 2σ = 38 °, which faces in the direction of an image from a collecting and a scattering meniscus lens, the concave surfaces of which face the aperture stop, the aperture diaphragm, a plane-parallel filter plate, a collecting cemented member composed of a diverging lens and a condenser lens, a condenser lens and a collecting meniscus lens whose concave surface faces the image, characterized in that the following five conditional equations are satisfied: -0.02 f '<r₃- r₄-d₂ <0.05 f '(1),
0.45 f '<l₂ + d₃ / n₃ + l₃ <0.80 f' (2),
n₄-n₅ <0.03 (3),
1.73 <(n + + n + + n) / 3 (4),
51.0 <(ν₅ + ν₆ + ν₇) / 3 (5), where the symbols have the following meaning: f '- total focal length,
r _i - radius of the i-th system surface,
d _j - center thickness of the jth element,
l _k - k-th air distance,
n _j - refractive index n _{e of} the jth element
ν _j - Abbe's number ν _{e of} the jth element. 2. Lens according to claim 1, characterized in that the following design data is present: f '= 1 relative aperture 1: 1.4 s' = 0.528 Field angle 2σ = 38 °