DD132152B1 - LIGHT-SUBJECT LENS WITH BIG FRAME OF EDGE - Google Patents

Description

1.6241

1.7231

1.6241

63.9 63.9 63.9 28.1 49.0

36.1 29.3

36.1

For this 1 page drawing

Field of application of the invention

The invention is predominantly used in the screen photography for imaging the phosphor screens, such. B. X-ray or Oszillografenschirme applied to photosensitive layers.

Characteristic of the known technical solutions

Previously known objects for the specified field of application consist in the light direction, that is seen from the object to the image, from a group of converging lenses, a biconcave lens member, a Biconvex lens and two other lens members, of which the penultimate a thick and the image hollow meniscus and the last is a plano-concave Smyth lens, which turns its plane surface to the image. These or similar constructions are so far only suitable for relatively small image fields with a maximum diameter of 0.9 times the focal length. In this case, such a strong field curvature already occurs in these known objects that further enlargement of the usable field of view is impossible. Apart from the strong curvature of the field of view, the distortion also becomes disturbingly noticeable in the case of larger image fields.

Technically, the known lenses have the disadvantage that the group of converging lenses contain two lenses with glasses whose refractive indices are greater than 1.6. These glasses are generally particularly heavy and relatively expensive, which is particularly noticeable when larger image fields, the lens diameter compared to the diameter of the

Acsenbüels must be inflated.

In WP 107348 it was attempted to improve the image performance и = і эіпет within a field diameter up to a maximum of 0.9 times the focal length with a simultaneous economic saving by introducing glasses with extremely high refractive indices over 1.7 for the Smyth lens were. However, even in this case remains a relatively high pincushion distortion, greater than 5%, especially in image fields on the order of 0.9 times the focal length,

consist.

For image fields with a diameter larger than the focal length, the principle of the use of high-refractive lenses in field lenses can not be negotiated, since otherwise the strongly inclined coma rays would be totally reflected at the plane surface of the Smyth lens.

Object of the invention

With the help of the invention, it should be possible to photograph images on screens of imagers with shorter exposure times in space-saving arrangements as possible.

-2- 2CO 335

Explanation of the essence of the invention

The invention has for its object to provide an objective which is characterized at an opening of at least 1: 0.8 and a magnification / 3 = 1: 4, an image circle diameter greater than the focal length. At the same time, the effective glass mass of the front lens is to be reduced in such an objective and, moreover, an economical saving can be achieved by completely dispensing with heavy-duty lenses in the front lenses and only a putty group appears in the entire lens.

According to the invention, a solution is achieved in that the group of converging lenses consists of three collecting individual lenses, whereby the refractive effect is distributed over several areas. In the same way, a favorable spherical aberration and even distribution of the collecting power is ensured by a total collecting effect of the thick meniscus in front of the Smyth lens. By these measures, the use of the cheapest and most lightweight Krongläser (eg BK glasses or BaK glasses) in the group of converging lenses, d. H. in the front lenses. Since the use of a high refractive index glass in the Smyth lens is prohibitive for image field diameters greater than the focal length due to the otherwise occurring total reflection, a change in the optical path for highly inclined light beam must be achieved by geometric means to achieve a zonal correction of field curvature. This is achieved by the fact that the air space located between the biconcave lens member and the subsequent biconvex lens takes the form of a collecting, strongly bent and hollow to the image meniscus, whereby an extreme bending (refraction) of the inclined bundles - and especially their upper Komastrahlen - takes place and the desired extension of the optical path is achieved. The air meniscus forming optically refracting surfaces must be so strongly curved that their radii are smaller than the lens focal length. Too much astigmatic undercorrection for the image edge is thereby avoided by the scattering effect of this aerial meniscus whose image-side optically refracting surface has a radius at least 10% greater than the object side. Due to the strong deflection and the thickness of the air meniscus, which is between 5% and 20% of the focal length, the coma correction is possible in addition to the field flattening. However, this specific effect of air meniscus is achieved only when the biconcave lens member is sufficiently thick. Corrected lenses of the type according to the invention are possible with a thickness of the biconcave lens element which is more than 0.3 times the focal length.

Due to the relatively high refractive power of the biconcave lens member can be dispensed with such a construction on a cemented surface within this member for the purpose of achromatization, so that the entire lens consists of only eight lenses. Design elements calculated according to the specified conditions are given in the table for an objective according to the invention.

embodiment

With reference to the drawing, some explanation of the invention will be given below. It shows:

Figure: a lens sectional image according to the table

In the table, the construction elements for an embodiment of the lens type according to the invention are given.

For the front lenses, the cheap BK7 glass was used. In general, the example ensures a special economic production.

Because of the improved correction of the upper coma, in the example the diameter of the front lens can remain very small; and especially that of the first lens need only exceed the diameter of the axial bundle of rays by less than 10%.

Claims (1)

Claim: High-intensity lens with large image field and a magnification / 3 = 1: 4, characterized in that the lens is characterized by the following construction elements in the table: Focal length f = 1 Relative aperture 1: 0.8 Image scale / 3 '= 1: 4 image circle diameter = 1, If Radii Thicknesses and Clearances Refractive indices η _θ Abbe numbers _β r _{1 =} +1.4672 r ₂ = -17.6051 r ₃ = + 1.7097 r ₄ = + 5.7292 r ₅ = + 1.1023 r ₆ = + 4.0704 r ₇ = -3.0626 r ₈ = + 0.7660 r ₉ = + 0.9637 r ₁₀ = -1.7431 T ₁₁ = +1.3931 r ₁₂ = -0.5582 r ₁₃ = + 4.3358 r ₁₄ = -0.6884 (J, = 0.2686 1 ₁ = 0.0016 O ₂ = 0.1709 1 ₂ = 0.0016 d ₃ = 0.1831 1 ₃ = 0.1123 d ₄ = 0.3288 1 ₄ = 0.1494 d ₅ = 0.2832 1 ₅ = 0.1095 d ₆ = 0.4843 d ₇ = 0.0769 1 ₆ = 0.2828 d ₈ = 0.0488 1.5186 1.5186 1.5186 1.7343 1.6102