# Four-element lens

FIELD: photography.

SUBSTANCE: invention can be used as a photographic lens. Lens consists of two components. First component comprises two single lenses – plane-convex, by convex side facing object space, and concave with concave side facing object space. Second component is in form of glued convex-concave negative meniscus, by convex side facing object space, and a biconvex lens. Between refraction indices n_{1}, n_{2}, n_{3}, n_{4} of first, second, third and fourth lenses, respectively, for D spectral line ratios are met 1.5<n_{1}=n_{4}<1.6, 1.6<n_{3}<1.7, 1.6<n_{2}<1.7, n_{3}<n_{2}. Air gap between components of lens varies from 0 to 0.4 ƒ’, where ƒ’ is focal distance of whole system, wherein image quality in center remains unchanged.

EFFECT: technical result is high aperture ratio, wider angular field in object space and possibility of portrait photography with variable artistic perception of photography.

1 cl, 2 dwg, 2 tbl

**Same patents:**

FIELD: physics, video.

SUBSTANCE: invention can be used in video cameras with a CCD array. A variable focus lens comprises four components and an aperture diaphragm placed in front of the fourth component. The first and fourth components are positive, the second and third components are negative and are capable of moving along an optical axis. The first component comprises a positive lens, glued from a negative meniscus and a biconvex lens, a positive lens and a positive meniscus. The second component comprises a negative meniscus, a biconcave lens and a positive meniscus. The third component is negative and is glued from a positive meniscus and a biconcave lens. The fourth component comprises a double-glued lens from a biconvex and a biconcave lens, a positive meniscus, a negative meniscus, a biconvex lens, two negative menisci and a biconvex lens. Relationships given in the claim are satisfied.

EFFECT: wider field of view and reduced relative distortion while maintaining high image quality in the entire measurement range of focal distance of the variable focus lens, which is not less than 5,5 units.

7 dwg

FIELD: physics.

SUBSTANCE: first component is fixed and is in form of a positive meniscus whose convex surface faces the object space, the second movable component is in form of a biconcave lens, the third component is fixed and the first two menisci therein are positive and face each other with their convex surfaces, and third component is a plane-concave lens, whose flat surface faces the image plane, the fourth fixed positive component includes three menisci whose concave surfaces face the image plane, the first and third menisci of which are positive and the second meniscus is negative. The second surface of the lens of the first component, the first surface of the lens of the second component and the concave surface of the first positive meniscus of the fourth component are aspherical.

EFFECT: high transmission factor of the optical system and manufacturability while maintaining a high aperture ratio, differential magnification and image quality.

8 dwg, 1 tbl

**FIELD: **optics.

**SUBSTANCE:** objective lens can be applied for thermal imagery devices with smoothly altering field of vision; the objective lens contains the first consistently located fixed element in the form of a collecting convex-concave lens, the second movable element consisting of the first defocusing convex-concave lens and the second concavo-concave lens, the third movable component in the form of the convexo-convex lens and the last immovable component containing the first collective convex-concave lens and the second defocusing concave-convex lens; the focal distance f_{1} of the first component is selected in accordance with the dependency: f_{1}=(from 0,545 to 0,8)f_{t}, wherein f_{1} is the focal distance of the first component, f_{t} - the maximum focal distance of the objective lens.

**EFFECT: **demagnification of the length of the infrared objective lens regarding maximum focal distance upon the retention of sufficiently high image quality.

1 dwg, 3 tbl.

FIELD: physics.

SUBSTANCE: objective lens consists of four series-arranged components: the first is convergent, the second is divergent and third and fourth are convergent. The first component is immovable in zooming mode and is movable in macro-mode and consists of a converging and a diverging lens glued together. The second component is movable and contains a biconcave lens and consists of a converging and a diverging lens glued together. A shutter with an aperture diaphragm, having two fixed openings, lies between the second and third components and can move together with the third component. The distance from the centre of the shutter to the CCD matrix lies in the range of 0.42…0.50 times the total length of the objective lens. The third component is movable and consists of a converging and a diverging lens glued together and a divergent-meniscus lens. The fourth component is movable and consists of a divergent- and a convergent-meniscus lens and a converging lens.

EFFECT: fewer number of lenses and aspherical surfaces while maintaining or improving functionalities of the objective lens.

3 cl, 9 dwg, 3 tbl

FIELD: physics.

SUBSTANCE: telescope has an exit pupil position which does not change when magnification is changed outside the eyepiece and an entrance pupil which is superposed with a first lens during high magnification. The telescope has a positive objective lens which includes a first positive, second and third negative menisci whose concave surfaces face the plane of the exit pupil, and an eyepiece which includes a fourth positive meniscus whose convex surface faces the exit pupil, and a fifth fixed positive meniscus whose concave surface faces the plane of the exit pupil. The third and fourth menisci have two fixed positions each and small displacements in these positions. Parameters of the telescope are related through relationships given in the formula of invention.

EFFECT: simple design, reduced cost price, high transmission coefficient owing to fewer lenses in the system, reduced internal background noise and reduced impact of Narcissus effect.

6 dwg, 6 tbl

FIELD: physics.

SUBSTANCE: telescope has a real and fixed position of the exit pupil outside the eyepiece of the telescope when the magnification changes and has on the beam path a first and a second negative meniscus whose concave surfaces face the plane of the exit pupil and form the objective lens, as well as a movable third biconcave lens having two fixed positions, a fourth biconvex lens, a fifth negative and a sixth positive meniscus whose convex surfaces face each other and form the eyepiece. The third lens has ratio of radii of refracting surfaces whose absolute value is close to 1. Parameters of the telescope are related through relationships given in the formula of invention.

EFFECT: simplification of design owing fewer movable elements with preservation of diffraction limited image quality, low distortion and reduction of magnifying power by three times.

8 dwg, 7 tbl

FIELD: physics.

SUBSTANCE: objective has fixed positive first and last components between which there is a movable negative meniscus whose convex surface faces the image plane and a positive component. The first component contains a positive and a negative meniscus whose concave side faces the image plane. The last component is in form of two positive menisci whose convex surfaces face each other, and a negative meniscus whose concave side faces the image plane. The movable component includes a divergent and a convergent lens and a negative meniscus whose convex side faces the image plane lying tightly in front of the divergent lens of this component. The aperture diaphragm is placed between the objective lens and the image plane. The entrance pupil is superposed with the first surface of the objective lens.

EFFECT: exclusion of aspherical and diffraction optical elements, reduced diameter of the objective lens and distance from the aperture diaphragm to the image plane with maintenance of high aperture ratio, drop in magnification and image quality.

8 dwg, 1 tbl

FIELD: physics.

SUBSTANCE: telescope can be used in thermal imaging devices as an afocal system for increasing equivalent focal length, changing magnification and fitting a scanning element in the exit pupil of the telescope. The telescope has a position of the exit pupil which does not change when magnification is changed and has four components. The first component is a single positive meniscus whose concave side faces the plane of the exit pupil. The second component is a first moving biconcave lens. The third is a second moving lens in form of a positive meniscus whose convex side faces the plane of the exit pupil. The fourth component is a fixed single positive meniscus whose concave side faces the plane of the exit pupil. The lens are made from two types of material. The movable lenses are made from different materials, move in opposite directions and each has two fixed positions.

EFFECT: simple design, increased transmission capacity and reduced weight while maintaining three-fold drop in magnification and diffraction-limited image quality.

4 cl, 8 dwg, 1 tbl

FIELD: instrument engineering.

SUBSTANCE: lens system consists of five in-series located elements. The fixed first element consists of positive and negative lenses. The second and third movable elements are installed with the possibility of being moved along optical axis. The second element contains a negative lens, and the third one is made in the form of a negative concave-convex lens. The fourth fixed element is made in the form of a positive concave-convex lens, and the fifth fixed element includes the first and the second positive convex-concave lenses. The second surface of the first lens is aspherical. Negative lens of the movable second element is double concave.

EFFECT: decreasing length of infrared lens system relative to its maximum focal distance with simultaneous increase of changing interval of focal distance at maintaining image quality.

2 cl, 1 dwg

FIELD: physics; optics.

SUBSTANCE: proposed telescope has an invariable position of the exit pupil when changing zoom and comprises a first positive component in form of a positive and a negative meniscus, whose concave side faces the exit pupil, a second negative component from a positive meniscus, whose convex side faces the exit pupil, a biconcave lens, a third positive component in form of a meniscus, whose convex side faces the exit pupil, and a fourth positive component in form of two meniscuses, whose convex sides face each other. All these components are arranged in series along the beam path. The second and third components can move along an optical axis. All refracting surfaces of the telescope are spherical. The negative meniscus of the first component, first meniscuses of the second and fourth components are made from zinc selenide, and the rest of the lenses are made from germanium.

EFFECT: reduced weight and size, reduced distortion, increased differences in zoom by up to ten times with retention of the diffraction quality of the image in the whole field, meeting requirements of limiting the Narcissus effect at the same time.

3 dwg

FIELD: optics.

SUBSTANCE: first positive component has positive lens, glued from negative meniscus, directed by convex surface to a space of objects, and biconvex lens, and positive meniscus, directed by convex surface to objects space and glued together from biconvex and biconcave lenses. Second component contains biconvex lens of negative bi-glued meniscus, directed by convex surface to objects space and consisting of negative and positive meniscuses. Third component is made in form of negative lens, glued from positive meniscus, directed by convex surface to images space, and biconcave lens. fourth positive component consists of two groups of lenses, apart from each other for distance not less than half of back focal length of auto-zoom lens. second and third components are mounted with possible movement along optical axis.

EFFECT: broader range of focus ranges of lens with maintained high quality of image.

6 dwg

FIELD: photography; optics.

SUBSTANCE: zoom belongs to objectives with variable focal length and it can be used as video camera's objective providing formation of image onto CCD array. Zoom has four components and aperture diaphragm. First, third and fourth components are positive ones, and the second component is negative one. Aperture diaphragm is disposed in front of the third component; second and fourth components are mounted for movement along optical axis. First component has positive double-cemented lens, which has negative meniscus turned with its convexity to space f objects, and of positive lens. First component also has positive menisci turned with its concaved surface to space of images. Second component has two negative lenses and positive double-glued lens, which is composed of negative menisci turned with its convex surface to space of objects, and of positive lens. First negative lens of second component is biconvex. Positive lens of second component is made in form of menisci turned with its convex surface to space of objects. Third component has positive double-cemented lens, which is composed of biconvex and biconcave lenses, and positive meniscus, which is turned with its concave surface to space of objects. Distance between positive double-cemented lens and menisci of the third component has to be equal or longer than 0,1 focal length of the component. Sum of optical powers of components does not exceed 0,00036 mm-1.

EFFECT: improved quality of image; increased factor of modulation transmission through the whole field of view within whole range of changes in focal lengths.

6 dwg

FIELD: optical engineering.

SUBSTANCE: objective has five components. First component is motionless and it is made of two positive menisci turned with their convexity to object. Second meniscus is glued of positive and negative lenses. Second and third components are mounted for movement along optical axis. Second and third components are made in form of single biconcave and biconvex lenses. Fourth component has to be collective, the fifth component is projection system made in form of single biconvex and of three positive menisci; the first and the second menisci are turned with their convexity to object; the third meniscus is turned with its convexity to image. Device also has aperture diaphragm. First meniscus of the second component is glued of single biconvex and biconcave lenses. Positive and negative lenses of second meniscus of first component are made in form of single biconvex and biconvex lenses correspondingly. Aperture diaphragm is placed between biconvex lens and first positive meniscus of fifth component. For that the relation are made which relations are shown in formula of invention defining requirements to materials for making first, second and third components of objective and requirements to designing parameters of objective.

EFFECT: improved precision of image.

1 dwg

FIELD: the invention refers to optical devices.

SUBSTANCE: the objective has in-series located the immovable first component in the shape of a positive convex-concave lens, the second movable component in the shape of a negative concave-concave lens, the movable third component in the shape of a negative concave-convex lens, the immovable the fourth component in the shape of a positive concave-convex lens and the fifth component consisting of the first positive convex-concave lens, the second negative convex-concave lens , the third negative lens, the fourth lens and the fifth positive lens, in the fifth component the third lens is fulfilled concave-concave, the fourth - negative convex-concave and the fifth - convex-convex. At that the first surfaces of the third and the fifth lenses of the fifth component are fulfilled aspherical.

EFFECT: reduces the length of the infrared objective relatively to its maximum focal distance at preserving relation of the maximal focal distance to minimal and also increases concentration of energy in the given circle of scattering.

4 cl, 1 dwg

FIELD: optical engineering.

SUBSTANCE: objective with smoothly changing focal length has motionless first component, having positive concave-convex lens being capable of movement along optical axis, disposed in series with movable second component supplied with negative concave-convex lens, and third component made in form of negative concave-convex lens, motionless fourth component made in form of positive concave-convex lens, and fifth component having first and second positive concave-convex positive lenses. First component additionally has negative concave-convex lens, third negative biconcave, fourth positive biconvex and fifth positive convex-concave lenses. Second surface of first lens of fifth component is made aspheric.

EFFECT: increased time of change in focal length; reduced length of objective; improved quality of image.

3 cl, 1 dwg

FIELD: optical engineering.

SUBSTANCE: objective can be used as objective of devices operating within IR spectrum range for detecting, distinguishing and recognizing objects. Objective has two motionless positive components and mo able negative component disposed those two negative components. First component being dispose along path of beams is made in form of meniscus turned with its concavity to plane of image. Last component is made in form of single menisci turned with its concavity to plane of image. Negative component is made in form of single biconcave lens. Positive component is introduced between negative component and last positive component. Positive component is made in form of menisci turned with its concavity to plane of image. Meniscus is tightly connected with aperture diaphragm and is capable of moving together with diaphragm along optical axis. Surface of menisci, which surface comes in front of aperture diaphragm, is made aspherical. The following conditions are met in the system: n_{1}=n_{2}=n_{3}=n_{4}=4,0, -f'_{3}<f'_{2}<-1,1f'_{4}, 2,7f'_{3}<f'_{1}<3f'_{3}.

EFFECT: higher technical parameters; improved quality of image; reduced sizes.

4 dwg

FIELD: optical objectives.

SUBSTANCE: IR objective has the following members disposed in series: motionless first component in form of positive concave-convex lens; movable second component composed of first negative convex-concave lens and second convex-concave negative lens; movable third component; motionless fourth and fifth components. Focal lengths f_{1} and f_{5} of first and second components correspondingly are chosen in dependence of maximal focal length of IR objective to be the following: f_{1}=(0,804-0,948)f_{t} and f_{5}=(0,342-0,346)f_{t}, where f_{1} and f_{5} are focal lengths of first and fifth components correspondingly and f_{t} is maximal focal length of objective.

EFFECT: reduced length of IR objective in relation to its maximal focal length at changes in multiplicity of change in focal length.

1 dwg