RU2189064C2 - Telescopic optical system - Google Patents

Abstract

FIELD: optics. SUBSTANCE: telescopic optical system includes three lenses: biconcave lens, single positive meniscus facing image with convexity and plano- convex lens. All three lenses can be fabricated from one material. Visible magnification of system is 0.1, field of vision is 40 angular minutes, diameter of exit pupil is 4.0 mm. EFFECT: high-quality image. 4 cl, 1 dwg, 2 tbl

Description

 The invention relates to optical instrumentation and can be used in various devices.

Galilean telescopic systems are known for observing distant objects, consisting of a lens and an eyepiece and containing three components. However, they either have more than three lenses, or are characterized by a long length (A.S. USSR N 1024992, IPC G 02 B 23/00, publ. 1993; RF patent N 1811625, IPC G 02 B 23/00, publ. 1993)
The closest analogue to the claimed technical solution is the Galilean telescopic system (G. Slyusarev. Calculation of optical systems. Leningrad, "Engineering", 1975, p. 195, Fig. 11.32), containing three components:
- the first is a positive meniscus convex to the subject;
- the second is a positive meniscus convex to the object, consisting of two glued lenses located along the beam of a biconvex and biconcave;
- the third component is a biconcave lens,
moreover, in the telescope, the ratio R2 / R1 = 2.056 takes place, where R1 is the radius of the first optical surface, R2 is the radius of the second optical surface, and, in addition, the refractive index of the first component is n _g = 1.5726, and that of the positive lens included in the second component n _g = 1.5726 and negative lens n _g = 1.6245. This system also has a large length of 77.2 mm; in the reverse course of the rays, its apparent increase is large (0.25 times). Recalculated for a visible increase of 0.1 times the system does not provide the required image quality with a small length.

 The objective of the invention is the creation of a telescopic optical system with a visible increase of 0.1 times with high image quality with an exit pupil diameter of 4 mm, a field of view of 2w = 40 arcmin and a short length.

 The technical result due to this task is achieved by creating a telescopic optical system containing three components, the first of which is a biconcave lens, the second is a positive meniscus, convex to the image, and the third is positive. In contrast to the known, the second component is made in the form of a single lens, and the third - in the form of a plano-convex lens, facing the subject with a plane.

The refractive indices n _{D of the} second and third components individually or both together may be greater than 1.63. All three lenses can be made of the same material.

 The drawing shows an optical diagram of the proposed telescopic optical system.

The telescopic optical system consists of three components sequentially installed - a biconcave lens 1, a positive meniscus 2, convex to the image and made in the form of a single lens, a plano-convex lens 3, the plane facing the object. The refractive index n _{D of} lenses 2 or 3, or both of lenses 2 and 3, may be greater than 1.63. The lenses 1, 2 and 3 of the system can be made of the same material, for example, TF5 glass.

 In accordance with the proposed solution, two variants of the telescopic optical system are calculated. The first option has design parameters shown in table. 1.

 Characteristics of the calculated telescopic system: visible increase - 0.1 times; exit pupil diameter - 4 mm; field of view angle - 40 ang.min; length - 44.8 mm.

 The telescopic optical system has the following aberrations for λ = 1060 nm: angular spherical aberration for a point on the axis - not more than 0.1 angles. from; angular spherical aberration of a wide inclined beam: in the meridional section for the field of view 2w = 40 ang. min - not more than 1.4 angular sec; in the sagittal section - not more than 0.3 arc.s; meridional astigmatic segment - not more than 0.0013 diopters; sagittal astigmatic segment - not more than 0,00025 diopters.

 The second calculated version of the system has design parameters shown in Table 2.

 Characteristics of the second calculated option: visible increase - 0.1 times; exit pupil diameter - 4 mm; field of view angle - 40 ang.min; length - 29.42 mm.

 Aberrations for λ = 1060 nm: angular spherical aberration for a point on the axis no more than 0.7 ang. from; angular spherical aberration of a wide oblique beam: in the meridional section for the field of view 2w = 40 ang. min - not more than 0.2 ang. from; in the sagittal section - not more than 0.6 arc.s; meridional astigmatic segment - not more than 0.001 diopters; sagittal astigmatic segment - not more than 0,0003 diopters.

 Thus, as a result of the proposed solution, a technical result is obtained: a telescopic optical system with a visible magnification of 0.1 times, a field of view of 40 angles is created. min, exit pupil diameter of 4 mm and high image quality.

Claims (5)

 1. A telescopic optical system containing three components, the first of which is a biconcave lens, the second is a positive meniscus convex to the image, and the third is positive, characterized in that the second component is made in the form of a single lens, and the third is in the form of a convex lenses facing the subject. 2. The telescopic optical system according to claim 1, characterized in that the refractive index of the second component is n _D > 1.63. 3. The telescopic optical system according to claim 1, characterized in that the refractive index of the third component is n _D > 1.63. 4. The telescopic optical system according to claim 1, characterized in that the refractive indices of the second and third components are n _D > 1.63.  5. The telescopic optical system according to claim 1, characterized in that all three lenses are made of the same material.

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