DD291854B5 - LIGHT-SENSIBLE SEX-LINE LENS - Google Patents

Description

Field of application of the invention

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

Characteristic of the known state of the art

Lenses for this purpose, which are characterized by a high 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, have no uniform image quality over the entire image field or contain more than six lenses. From US-PS 4671626 a five lens lens with a relative aperture of 1: 1.73 is known. For the required relative aperture of 1: 1.4, the required correction of the image errors can no longer be achieved with this lens type. Siebenlinsige lenses are known from the patents DD 160501 and DD 245059 A1. These lens types have the required relative aperture of 1: 1.4, but the construction of seven lenses results in an increased production cost and the lens type according to DD 160501 does not allow a compact lens.

In DE 2057602 a six-lens objective consisting of a condenser lens, a diffusing meniscus lens, a collecting cemented member, a condenser lens and a collecting meniscus lens is described for a relative aperture of 1: 1. This lens is not suitable for the required field angle of 2δ = 38 °, as it does not characterize this field angle with the required correction. The cause is the field curvature that occurs with this lens at large field angles and the astigmatism that is present.

Object of the invention

The aim of the invention is to eliminate the disadvantages of the prior art and to develop a powerful lens for the stated application. This should be given an economical production.

Explanation of the essence of the invention

The invention has for its object to provide a fast lens with a relative aperture of 1: 1.4 and a field angle of 2δ = 38 ", which is uniformly well corrected for the entire image field.

According to the invention, this object is achieved in such a lens, which consists of a collecting and a scattering meniscus lens whose concave surfaces to the aperture stop, the aperture stop, a plane-parallel filter plate, a collecting cemented member, which consists of a diverging lens and a converging lens, a converging lens and a collecting meniscus lens whose concave surface faces the image plane is solved by satisfying the following conditional equations:

-0.02 Γ <r ₃ -r ₄ -d ₂ <0.05 Γ (1),

0.45 f <1 ₂ + d ₃ / n ₃ + 1 ₃ <0.80f (2),

n ₄ -n ₅ <0.03 (3),

1.73 <(n ₅ + n ₆ + n ₇ ) / 3 (4),

51.0 <(V ₅ + V ₆ + V ₇ ) / 3 (5),

in which the symbols have the following meaning:

f total focal length,

r; Radius of the i-th system surface,

d, middle thickness of the jth element,

l _k -k-th air clearance,

tij - refractive index n "of the jth element

V ₁ abbreviation NumberV _{e of} the jth element

The aperture space is dimensioned so that it allows the installation of a filter plate.

As a result of this construction according to the invention and the choice of design parameters, the system type known in principle can be used for a larger field of view with balanced correction of all aberrations. At the same time, it has been achieved that the image aberration, which greatly increases due to the necessary large diaphragm space for the use of the filter plate, can be compensated and a slight distortion is achieved.

According to the invention, the collecting cemented element has a small refractive index jump on the cemented surface according to condition (3). The radius of the surface to the aperture space is designed so that for the main beam, a small angle of incidence and thus a small deflection by the refraction occurs at this surface, which has a favorable effect on the coma correction. Due to the relatively strongly curved cemented surface in combination with the low refractive index jump, it contributes significantly to the correctability of the astigmatism.

The condensing lens and the collecting meniscus were constructed according to the invention according to condition (4) of high refractive index glass. In conjunction with the choice of the radii of curvature, a uniform distribution of the beam deflection was achieved on the lens surfaces. This leads to the compensation of the residual opening error, which is deliberately allowed at the dissipating meniscus lens.

Ausführungsboispiel

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

Fig. 1 shows the lens sectional image and Fig. 2, 3 and <\ show graphical representations of the correction state of the solution according to the invention.

Fig. 1 shows the Linsenschnittbüd the orfindungsgemäßen objective. Thereafter, the objective consists in the light direction of a collecting meniscus lens L1 and a scattering meniscus lens L2, the concave surfaces of the aperture stop, the aperture B, a plane-parallel filter plate P, a weakly collecting cemented K1, consisting of a diverging lens L3 and a converging lens L composed of a converging lens L5 and a collecting meniscus lens L6, the concave surface of which faces the image.

The uniformly good correction over the entire image field is due to the described arrangement of the lenses L1 to L6, the filter plate P and the aperture diaphragm B with the radii r ,, the center thickness dj, the refractive indices n _e and Abbe numbers v _e , and the air gaps l _k , whose values are given in the table to claim 2.

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

3 shows the length deviations of the sagittal and meridional image shell as a function of the field angle o.

4 shows the distortion as a function of the field angle u.

Claims (2)

1. A bright six-lens objective with a relative aperture of 1: 1.4 and a field angle of = 38 °, in the direction of image from a collecting and a scattering meniscus lens whose concave surfaces to the aperture stop, the aperture stop, 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 <r ₃ -r., - d ₂ <0.05f (1), 0.45 f <I ₂ + d ₃ / n ₃ + I ₃ <0.80 Γ (2), n ,, - n ₅ <0.03 (3), 1.73 <(n _s + n ₆ + n ₇ ) / 3 (4), 51, CX (VIV ₆ + V ₇ ) / 3 (5), in which the symbols have the following meaning: f total focal length, r, radius of the i-th system surface, dj -mid-thickedesj-th element, l _k -k-th air clearance, nj -Brechzahl n th element of _e Desj Vj abbreviation NumberV _{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 2 a = 38 ° For this 1 page drawings