RU2445659C1 - Large-aperture lens - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: lens can be used as a receiving lens in devices with photodetectors, e.g., CCD matrices, including in the infrared region as well. The lens consists of seven components on the beam path. The first component is a single converging-meniscus lens whose concave side faces the object, the absolute value of the curvature radius of the first surface of which is less than that of the second surface. The second component is a converging-meniscus lens whose convex side faces the object and is glued from two converging-meniscus lenses. The third component is a divergent-meniscus lens whose convex surface faces the object. The fourth component is glued from a biconcave and a biconvex lens. The fifth component is a single biconvex lens. The sixth component is glued from a biconvex lens and a divergent-meniscus lens whose concave side faces the object. The seventh component is a single divergent-meniscus lens whose convex side faces the image.

EFFECT: high image quality.

3 cl, 1 dwg, 2 tbl

Description

The present invention relates to optical instrumentation and can be used as a receiving lens in optical devices operating with photodetector devices, for example with CCD arrays, including in the infrared range of the spectrum.

Known optical system of a lens for aerial photography [US Patent No. 2628532, NKI 350-466, publ. 1953]. However, this lens has a complex structure (consists of 11 lenses) and an insufficient relative aperture of 1: 3.5.

The closest analogue to the claimed technical solution is the lens system of the lens for microfilming [US Patent No. 4200352, NKI 350 / 1.2; 350/214, publ. 1980, implementation 1], consisting of seven components separated by air gaps, the first of which along the rays is a single biconvex lens, the radius of curvature of its first optical surface being less than the radius of curvature of its second optical surface, and the second is a single positive meniscus convex to the object, the third is a single negative meniscus convex to the object, the fourth component is glued from a biconcave and biconvex lens, the fifth is a positive component nny of a negative meniscus which is convex to the object and a biconvex lens, a sixth component - a single biconvex lens and a seventh component - positive meniscus convexity and glued to the object of the negative and positive meniscus. The aperture diaphragm is located between the third and fourth components.

This lens, recalculated to a focal length of 64.7 mm, when operating from infinity with a relative aperture of 1: 1.5 and a linear field in the image space of 2U '= 43.26 mm, has insufficient image quality. So, for a wavelength of 587.56 nm at the edge of the field of view, it has a transverse aberration in the meridional section of 0.8419 mm and a distortion of 4.22%.

The objective of the invention is the creation of a fast lens with high image quality.

The technical result is an increase in image quality.

This is achieved by the fact that in a fast lens consisting of seven components separated by air gaps, the first of which is a single positive lens along the rays, the radius of curvature of its first optical surface being less than the radius of curvature of its second optical surface, and the second is the positive meniscus convex to the subject, the third is a single negative meniscus convex to the subject, the fourth component is glued from a biconcave and biconvex lens, the fifth component is positive, the external optical surfaces of which are convex spherical, the sixth component is positive, the external optical surfaces of which are convex spherical, and the seventh component is the meniscus, in contrast to the known component, the first component is made in the form of a meniscus facing concavity to the object, the second component is glued from of two positive menisci, the fifth component is a single lens, the sixth component is glued from two optical elements - the first, whose external optical surfaces are convex spherical, and the second optical of the element - a single negative meniscus, facing concavity to the subject, and the seventh component is made in the form of a single negative lens, convex to the image.

In addition, the refractive index of the first along the meniscus rays of the second component may be less than the refractive index of the second meniscus of the second component for the spectrum line e; the first optical element of the sixth component can be glued from two or more lenses and plane-parallel plates of the same glass grade.

The figure shows the optical scheme of a fast lens.

A high-aperture lens consists of a single positive meniscus 1 facing concavity to the object, a positive meniscus 2 convex to the subject, glued to a positive meniscus 3 convex to the subject, a single negative meniscus 4 convex to the subject, biconcave lens 5 glued with a biconvex lens 6, a single biconvex lens 7, a biconvex optical element 8, glued with a negative meniscus 9, facing concavity to the object, single The leg 10 of the negative meniscus facing to the image is convex, and the parallel plate 11. The aperture diaphragm is located at a distance of 11.15 mm behind the lens 4.

A fast lens works as follows.

The luminous flux emanating from the plane of objects at infinity passes through the fast lens and is displayed in the plane of the best setting in which the photodetector is located, for example, a CCD (not shown).

As a specific example of the invention, an aperture lens is calculated, corrected in the spectral range from 589.3 nm to 852.1 nm with the structural data presented in Table 1.

The calculated fast lens has the following characteristics.

The focal length of the lens f ' 64.7 mm Relative hole 1:15 Angular field in the space of objects 17 deg. 14 min Linear field in image space 2U '= 43.26 mm Back focal length 0.836 mm

In the present invention, the refractive index of the first along the rays of the meniscus of the second component is equal to 1,4485; and the refractive index of the second meniscus of the second component is equal to 1,747647 for the spectrum line e.

Table 1 Radii, mm Thickness mm Glass mark Refractive index n _e Coeff. variance, ν _e Light diameter mm R ₁ = -62,376 69 d ₁ = 6.5 TK21 1.659961 50.81 R ₂ = -63.973 70,2 d ₂ = 0.2 one R ₃ = 59.836 59 d ₃ = 7.7 OK4 1,4485 91.53 R ₄ = 91.41 55.7 d ₄ = 8 STK19 1,747647 50.21 R ₅ = 252.922 52 d ₅ = 0.2 one R ₆ = 34.987 49.9 d ₆ = 4 TK21 1.659961 50.81 R ₇ = 29,039 38.8 d ₇ = 14.05 one R ₈ = -59,295 35 d ₈ = 13.15 F1 1,616878 36.7 R ₉ = 39.081 41.7 d ₉ = 15.8 OK4 1,4485 91.53 R ₁₀ = -83,366 46 d ₁₀ = 0.2 one R ₁₁ = 49.99 55,4 d ₁₁ = 15 STK19 1,747647 50.21 R ₁₂ = -190.943 54.6 d ₁₂ = 0.2 one

Continuation of table 1 Radii, mm Thickness mm Glass mark Refractive index, n _e Coeff. variance, ν _e Light diameter mm R ₁₃ = 162.53 52,5 d ₁₃ = 41.8 TK14 1,615506 60.34 R ₁₄ = -24.21 41.2 d ₁₄ = 6.35 TF8 1.694729 30.89 R ₁₅ = -370,698 35.8 d ₁₅ = 7 one R ₁₆ = -28.64 35.1 d ₁₆ = 3.6 TK21 1.659961 50.81 R ₁₇ = -125.329 37.8 d ₁₇ = 3.6 one

41.7 d ₁₈ = 0.76 K8 1,518294 63.83

41.7

Table 2 shows the aberrations for λ = 0, 70652 μm for the proposed aperture lens according to a particular embodiment and the aberration for λ = 0.58756 μm for the closest analogue, calculated at a focal length of 64.7 mm. In this case, the plane of objects is at infinity.

The proposed fast lens has a higher image quality compared to the closest analogue, which follows from table 2.

table 2 Type of aberration The closest analogue The proposed fast lens (no more) Transverse spherical aberration for a point on the axis with a relative aperture of 1: 1.5 0.131 mm -0.00649 mm Transverse aberration of a wide inclined beam in the meridional section for a linear field in the image space 2U '= 43.26 mm 0.8419 mm 0.14 mm Transverse aberration of a wide inclined beam in a sagittal section for a linear field in the image space 2U '= 43.26 mm 0.4063 mm 0.029 mm Meridional astigmatic segment X _m for a linear field in the image space 2U ^' = 43.26 mm 0.966 mm -0.0713 mm Sagittal astigmatic segment X _s for a linear field in the image space 2U '= 43.26 mm 0.598 mm -0.0945 mm Distortion for a linear field in the image space 2U '= 43.26 mm -4.22% -0.754%

Thus, as a result of the proposed solution, a technical result is obtained: a fast lens with an improved image quality is created.

Claims (3)

1. A fast lens consisting of seven components separated by air gaps, the first of which is a single positive lens along the rays, the radius of curvature of its first optical surface being less in magnitude than the radius of curvature of its second optical surface, the second is the positive meniscus convex to object, the third is a single negative meniscus convex to the object, the fourth component is glued from a biconcave and biconvex lens, the fifth component is positive, external op whose natural surfaces are convex spherical, the sixth component is positive, the external optical surfaces of which are convex spherical and the seventh component is the meniscus, characterized in that the first component is made in the form of a meniscus facing concavity to the object, the second component is glued from two positive menisci, fifth the component is a single lens, the sixth component is glued from two optical elements - the first, the external optical surfaces of which are convex spherical and the second optical element is a single tritsatelnogo meniscus facing concavity to the object, and a seventh component configured as a single negative lens facing convex to the image. 2. The fast lens according to claim 1, characterized in that the refractive index of the first along the meniscus of the second component is less than the refractive index of the second meniscus of the second component for the spectrum line e. 3. A fast lens according to claim 1, characterized in that the first optical element of the sixth component is glued from two or more lenses and plane-parallel glass plates of the same brand.