SU1682959A1 - Monochromatic objective-collimator - Google Patents

Abstract

The invention relates to optical instrumentation and can be used in optical systems working in conjunction with semiconductor radiation sources. The purpose of the invention is to reduce the radiation flux reflected from the lens surfaces. The lens consists of four lenses (1,2,3,4) of one type of glass. The shape of the lenses and the magnitudes of the radii of the surfaces are chosen from the condition that first-order reflections from all eight surfaces form either a virtual image of the radiator or remote from the radiator itself, thereby achieving elimination of the optical feedback. The combination of two double-convex lenses 1.4c positive 3 and negative 2 meniscuses allowed us to obtain a high aperture (0.625) with a 4-lens scheme. 1 il.

Description

The invention relates to optics, and more particularly to optical systems that work in conjunction with point radiation sources.

The purpose of the invention is the reduction of the radiation flux reflected from the surfaces of the lenses.

The drawing shows a schematic optical diagram of the lens, where Ri, 2 ... 8 is the position of spurious images of the radiation source from eight surfaces.

The lens contains a biconvex lens 1, a negative meniscus 2, convex to the radiation source, a positive meniscus 3, turned concavity to the radiation source, and a biconvex lens 4. The radiation source (not shown) is located in the focus of the lens S.

In the proposed lens, good correction of spherical aberration at high aperture is achieved not by layering ”non-aberration aplanatic surfaces, but by mutual compensation of the spherical aberration of individual lenses. Using four lenses 1--4 from a single glass grade with a high refractive index, it was possible to achieve a real (in tg U) relative aperture of 1: 0.625. Spherical aberration in no area of the hole does not exceed 0.001 mm with f ¹ = 6 mm. Removing focus from the first surface of the lens (working distance) Si = -0.281 ¹ .

The first-order reflexes in the proposed lens are distributed as follows: six of them - from surfaces 1-4, 6 and 8 - give an imaginary image of the emitter, that is, they do not intersect the optical axis at all, the remaining two (from surfaces 5 and 7) giving a real image of the emitter, intersect the optical axis far enough from the emitter, at a distance of -0.55 f ¹ and -3.3 f ^1, respectively.

Given the large aperture of the lens, one should expect large aberrations, in particular spherical, when constructing an image of a radiation source with reflecting beams. The results of calculating spherical aberration for all eight reflections of the 1st order of the lens show

Compiled by V. Arkhipov Editor S. Patrusheva Tehred M. Morgenthal, despite the very large aberrations (dg) of some beams (for example, from 4, 6, 7, and 8th surfaces), the focus area of the lens is practically free of stray reflexes.

Thus, reflected radiation does not fall into the region of the emitter and adjacent to it (± 0.3 f ¹ ) (with the exception, of course, of the paraxial region), which guarantees the system from the occurrence of optical feedback. Reflexes of higher orders, due to their negligible intensity during multilayer vacuum bleaching, in any case do not make a noticeable contribution to the appearance of optical feedback.

In the proposed execution collimator, all lenses are made of TF 10 glass. Focal length f '= 6 mm, wavelength L = 0.863 μm.

The position of the images of the emitter relative to the 1st surface in the reverse after a single reflection from each of the eight surfaces of the lens and refraction through all previous surfaces

1,214

91,221

5.56

4.40

5-4.95

62.88

7-20.7

1.884.

Claims (1)

A monochromatic lens-collimator containing four single lenses, the first of which is positive, the second meniscus, the third is the positive meniscus facing concavity to the radiation source, the fourth is a biconvex lens, characterized in that, in order to reduce the radiation flux reflected from the surfaces of the lenses, the first the lens is biconvex, the second is in the form of a negative meniscus convex to the radiation source, while all lenses are made of material with a refractive index of at least 1.7, and the absolute tnye magnitude radii of lens surfaces in the order they are selected from the following relation with respect to the focal length 1.47: 2.19: 2.76: 1.16: 1.12: 0.73: 7.17: 2.43: 1.