Abstract: A lens system for micro film which provides high resolution over a wide range with a ultraviolet ray, and has transmittance sufficient for said ray and a long working distance on the image side. Said lens system comprises a first positive lens component, a second meniscus lens component, a third negative lens component, a fourth cemented doublet component, a fifth positive cemented doublet component, a sixth positive lens component and a seventh cemented doublet component consisting of a negative lens element and a positive lens element.

Abstract: The "eye-piece" for a non-Gallilean afocal infra-red telescope comprises a front element which is meniscus with a convex back surface of greater radius of curvature than its concave front surface but which has a thickness such that it is of positive power, and a back element of positive power with a convex front surface and a convex or concave back surface. Such an "eye-piece" can be used in combination with a variety of objective lens systems.

Abstract: The present invention provides a compact zoom lens which exhibits small distortion aberration. The lens system comprises, in order from the object side, a front lens group having a negative focal length and a rear lens group having a positive focal length. The front lens group is a first lens group. The rear lens group is separated into a second lens group having a positive focal length and a third lens group having a negative focal length. The overall focal length is variable by moving mechanically the first, second and third lens groups, but the position of the image surface is maintained constant. The first lens group comprises, in order from the object side, positive, negative and positive units. The second lens group comprises, in order from the object side, positive, negative and positive units. The third lens group comprises, in order from the object side, a positive lens, a double concave negative lens and a positive lens.

Abstract: The present invention provides a compact zoom lens which exhibits only small distortion aberration. The present invention comprises, in order from the object side, a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a negative focal length. The overall focal length is variable by moving mechanically the first, second and third lens groups, but the position of the image surface is maintained constant. In the zoom lens of the present invention, the resultant focal length of the first and second lens groups is positive during the entire zoom range, and the aerial spaces between the first and second lens groups and between the second and third lens groups, respectively, are reduced so that the overall viewing angle is also reduced. The first lens group is composed of a negative lens component and a positive lens component in order from the object side. The negative lens component is constructed using two negative lenses.

Abstract: The present application discloses an examination pattern for use in conjunction with ophthalmoscopes which provides a light transmissive opening at the pattern center to act as a reference point in the examination of the eye.

Abstract: In an optical system including a transparent optical body such as a lens and a light reflecting surface disposed in the rear of the transparent optical body with a spacer of a light absorptive material being sandwiched therebertween to ensure the relative position and other optical relationship of the body and the surface. The spacer is cemented to a rear surface of the transparent body for masking the light reflecting surface and preventing light rays from entering from the front of the transparent optical body to the light reflecting surface to be reflected back by the latter. According to the present invention, the front surface of the spacer to be cemented to the rear surface of the transparent optical body is, before being cemented, polished to a degree of roughness which prevents the occurrence of fringes due to interference at a possible small gap between the transparent optical body and the spacer.

Abstract: An improved scanning grating useful as an image scanner and spatial frequency filter, for a focusing detector to ascertain the focus of an optical system on deflecting the light incident from the optical system into two different directions for forming two images of the exit pupil or of parts thereof of said optical system. A slit grating is superimposed over the groove grating so that the ledges cover the peaks and the troughs thereof. It is thereby attained that the signals obtained from the peak and trough areas, which normally are more or less undefined, are exempt from evaluation. The ledges have a width ranging from 10 to 100 percent of that of the slit width.

Abstract: A zoom lens system consisting, from the object to the image side, of a positive front focusing lens group, a negative variator lens group, a negative compensator lens group and a relay lens group is provided. The variator lens group has three single lens elements, in which a negative meniscus shaped air space is formed between the second and third single lens elements. The relay lens group is divided into first and second sub-groups with a relatively wide air space formed therebetween, each of the first and second sub-groups has a pair of separate lens elements.

Abstract: A method and apparatus are disclosed for controlling the refractive state of the eye. The image of a visual target is continuously positioned close to, but offset from, the retinal plane of the eye to be controlled. The offset is in such a direction from the retina that as the eye attempts to focus on the image, the refractive state of the eye will change toward the desired goal. To increase the effectiveness of the method and apparatus, the position of the image is continually varied along the optical axis.

Abstract: A magnifying apparatus comprising a pair of mutually adjustable complementary magnifying elements wherein one of the elements is an elongated member having one flat surface and one transversely arcuate surface, and the other element is of a circular configuration having at least one convex surface.

Abstract: An achromatic objective lens having an aperture ratio of about 1:12 and a viewing angle of about .+-.1.degree. for use in an astronomical telescope is disclosed. The lens uses conventionally available optical materials matched to produce optimum compensation of various aberrations.

Abstract: A compact cata-dioptric objective lens system comprising a first, second, third and fourth lens components in which the first lens component is a positive meniscus lens, the second lens component has a primary mirror formed on its surface on the image side by leaving a transparent central portion, the third lens component has a secondary mirror formed on its surface on the object side and the fourth lens component is cemented to the second lens component. The cata-dioptric objective lens system is arranged so that the rays entered through the first lens component are reflected by the primary and secondary mirrors, pass through the transparent central portion of the second lens component and are imaged thereafter and so that the fourth lens component has a large thickness in order to eliminate detrimental rays.

Abstract: A retrofocus type lens having an angle of view at least 75.degree. and F number 1:2.0. The lens includes a first lens group of a divergent type, a second lens group of a convergent type and a third lens group of a convergent type. The first lens group includes in the order stated a positive meniscus lens, a negative meniscus lens, a positive meniscus lens and a negative meniscus lens. The second lens group includes a positive lens which is either a single lens or consists of a positive lens and a negative lens cemented to each other and with a front convex face directed toward an object to be photographed. The third lens group includes a positive lens having a rear convex face directed toward an image of the object, a biconcave lens with its front surface radius smaller than its rear surface radius, a positive meniscus lens with a convex surface facing the image and a positive lens. The biconcave lens and the positive meniscus lens are respectively replaceable with cemented doublet lenses.

Abstract: A view expanding apparatus mounted on the inside lower right hand corner of an automobile windshield for eliminating the blind spot in the rear view of a motorist. A mirror is pivotally coupled to a negative lens, which may be a Fresnel lens, and the mirror lens construction is secured to the inside of the windshield. The negative lens expands the field of view and the angle between the lens and the mirror is adjustable so that the mirror reflects the expanded field of view for observation by the driver.

Abstract: Compact, high performance low zoom ratio variable viewing angle lens systems are provided by constructing the lens systems of two lens groups separated by a variable aerial space and limiting the dimensions of the lens systems by various mathematical conditions.

Abstract: A pair of cylinder lenses have a combined power of zero when their cylinder axes are parallel and a small cross cylinder power when one lens is rotated until its axis is perpendicular to the cylinder axis of the other lens. Cross-cylinder lenses are used to determine the accuracy of the cylinder power and cylinder axis selected by the practitioner. By mounting one cylinder lens in a motor-driven ring-like lens mount having a member which engages another ring-like lens mount, a single motor can be used to drive both lenses; select between parallel cylinder axes and crossed cylinder axes; and rotate the crossed axis lenses as an assembly to the desired position.

Abstract: A microscope objective comprising a first, second, third, fourth and fifth lens components, in which the first lens component is a negative meniscus lens, the second lens component is a positive meniscus lens, the third and fourth lens components are positive cemented doublets and the fifth lens component is a negative cemented meniscus doublet, and for which the numerical aperture is large and the image becomes flat toward marginal portion.

Abstract: A parallel pencil of light, for example, a laser beam, is expanded by means of a cylindrical lens. The lens is fully cylindrical and has an optically thinner medium of cylindrical shape in its interior. The lens is arranged relative to the pencil of light so that total reflection occurs at the interface with the optically thinner medium.

Abstract: A spherical lens element and a concentric lens element receive light, in that order, from a wide field of view, and diverge all rays so that upon leaving said concentric element, the angles of all rays approximate that of radial lines. This light is then filtered through a concentric narrow bandpass filter to attenuate undesired background light, and is collected by a suitable light collector and detector. Apertures for selecting the field of view and F number are provided.

Abstract: A lens selection device for placing any one of three or more magnification lenses in an operative position where its optical axis aligns with a respective reference axis, a selected lens being shifted along a fixed path from a retracted position to the operative position thereof by separate drive means numbering one less than the quantity of the lenses. In the case of three lenses, for instance, a first drive means is used to shift a first lens, a second drive means is used to shift a second lens, and a follower means coupled with a third lens is used to shift it to its operative position when the first (or the second) lens is driven to its retracted position.