SU1529159A1 - Objective with stop behind lens - Google Patents

Abstract

The invention relates to optical instrumentation and can be used in the development of small-sized photographic lenses for cameras with an electronic diaphragm. The purpose of the invention is to improve the image quality by correcting off-axis beam aberrations and reducing distortion. The lens contains positive menisci 1,2,3, the lens 4 is bent and bent double, the lens 5 and co-convex double and the meniscus 6 are negative. The lens 5 and meniscus 6 can be made with a concentric air gap. Focal distance 35 mm, relative aperture 1: 2.8, field angle of view 63 °. 1 sec. and 1 hp ff, 4 ill.

Description

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The invention relates to optical instrument making, in particular to photographic lenses, and can be used in devices requiring lenses with an optical f-stop and high image quality.

The aim of the invention is to improve the image quality by correcting aberrations of off-axis beams and reducing distortion.

Figure 1 shows the principal optical scheme of the proposed lens; Fig. 2 is a graph of the polychromatic modulation transfer function (MTF) at an image point of 15 mm; fig. 3 shows a lens, an example of implementation; Fig. 4 is a graph of the MTF of this lens at a point of an image of 18 mm.

The lens consists of five components arranged successively along the beam, the first and second of which are positive menisci 1 and 2, facing the object space, the third - putting an equal meniscus 3 facing the aperture to the diaphragm, the fourth - a negative two-bent lens 4, and the fifth is a positive double lens convex lens, glued

from a double-domed lens 5 and denied

valuable meniscus 6.

The fifth component can be made pasted with a concentric air gap between the lenses 5 and 6 (FIG. 3).

The implementation of the third component in the form of positive mass 3, facing concavity to the diaphragm, provides the possibility of eliminating the positive distortion, as well as additional possibilities for correcting the astigmatism of off-axis beams and evenly throughout almost the entire field, which reduces the aberrations of oblique beams.

Thus, distortion is significantly reduced and Lachest is improved in the image, characterized by MTF.

The obtained lens has the following technical characteristics: the focal length of the lens is 35 mm; relative aperture - 1: 2,8; angular field in the space of objects - 63; the main length of the ox

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here - 546 nm; working interval of wavelengths - 435-656 nm.

The aperture diaphragm is located after the last surface of the lens at a distance of 0.9 mm.

Astigmatism at the image size in 18 mm is reduced and is 0.01 mm, at 15 mm - 0.0 $ mm, at 10 mm - 0.058 mm, MTF at a frequency of 20 LIN / MM at 18 mm is 0, 34

Making the fifth component pasted also reduces the curvature of the image.

In the object shown in FIG. 3, with the same focal length and relative aperture values, astigmatism at 0.0 mm is 0.015 mm, the image curvature at 18 mm is reduced and equal to 0.03 mm, MTF at a frequency of 20 lines / mm with 18 mm - 0.33. The relative distortion in the corner of the frame, which corresponds to an image size of 21.6, is 1.94%, which makes it possible to reduce the image elongation caused by this aberration by 0.12 mm.

Claims (2)

1. The lens has a four-lens diaphragm containing four components, the first and second of which are positive menisci convex to the object, the third is a double-curved lens, the fourth is a positive lens consisting of a double lens and a negative meniscus differing from that, in order to improve the image quality by correcting aberrations of off-axis beams and reducing distortion, a positive meniscus is set between the second and third components, convex to the object. 2. The lens according to claim 1, characterized in that the fourth component is filled up, while the second surface of the two-convex lens and the first surface of the negative meniscus are concentric. At -15 you go JO fO 50 / Mfi Phie. 2 Fig.Z SE 20 SO itO so U “/ V / v / f FiL Editor A.Lezhnina Compiled by V.Ahipov Tehred L. Serdyukova Proofreader L. Patay Order 7637 / A1 Circulation 513 VNIPPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., A / 5 . .. in.,. ™ ..., .-,. i. .- -. "..." | .. .. „“, i. Production and Publishing Combine Patent, Uzhorss d, ul. Gagarin, 101 Subscription