Showing papers on "Angular aperture published in 1975"

Analysis of the noncollinear acousto-optic filter

Abstract: Theoretical analysis of an acousto-optic filter using noncollinear interaction is presented. The various characteristics of the filter, including tuning curve, resolution, angular aperture and deflection angle, are determined. The theoretical calculations are in good agreement with the measured results of a TeO2 filter.

Beam focusing by aperture displacement in multiampere ion sources

Abstract: Results are given of an experimental study of beam focusing by aperture displacement (Δx) in duoPIGatron ion sources Measurements with a single aperture, accel–decel electrode geometry show that the beam deflection angle is linear with Δx/z for the round aperture and with Δx/z*2 for the slit aperture, where z and z* are, respectively, the extraction gap distance and the effective gap distance Applying the result of the single aperture study to the multiaperture duoPIGatron sources, it was possible to increase the neutral beam injection power to the Oak Ridge Tokamak (ORMAK) plasma by ?40% Also presented are a discussion and comparison of other work on the effect of aperture displacement on beam deflection

Noncollinear tunable acousto-optic filter

Abstract: An electronically tunable optical filter is described wherein an optical beam is diffracted by an acoustic beam the group velocity of which is noncollinear with the optical beam transmitted through the birefringent crystal medium. The frequency and the direction of the phase velocity of the acoustic wave are chosen for a given incidence direction of the optical beam so that the diffraction occurs for a band of optical frequencies centered about a predetermined optical frequency and a relatively large angular distribution of incident optical beams. The noncollinear acousto-optic filter has the following advantages: (i) it allows very simple coupling of optical and acoustic beams into the interaction medium, (ii) it allows the use of multiple transducers for increasing tuning range or varying resolution, (iii) it allows a broad class of crystals to be used as filter material, (iv) it has a large degree of freedom in the filter design for optimizing efficiency or angular aperture and throughput, realizing narrow or broad optical passband and (v) it provides the spatial separation of incident and transmitted light through the filter and thus can be operated without the use of polarizers.

Simple optical lens with a large aperture and large field

Abstract: The invention relates to single lenses with large aperture and large field. The paraxial parameters of a lens with spherical refractive surfaces are selected in advance. The lens aberrations are corrected in such a way by aspherization of the refractive surfaces, that the wave front aberration which is expanded in a series as a function of the aperture, at least contains sixth-degree terms. The invention may be employed in heads for reading audio or video information on rotary record carriers.

Birefringent polarization prism with a large angular aperture

Abstract: An apparatus for polarizing natural light incident on a polarizer with an intermediate layer of one birefringent or biaxial material mounted between a pair of prism substrates of a second birefringent or biaxial material with a liquid or other index matching medium between the prism substrates and the intermediate layer to provide optical coupling between the three above-mentioned constituent parts of the prism. The materials of the prism substrates and of the intermediate layer being selected to be substantially transparent and to have orthogonal indices of refraction (n o and n e for birefringent materials and any two of n a , n b and n c for biaxial materials) which are considerably different for each individual material over the spectral region of the desired polarization. Further, the material of the intermediate layer is selected such that its greatest index of refraction curve is substantially equal to the lowest index of refraction curve of the material of the prism substrates over the spectral region of the desired polarization, and the optic axes of these materials are oriented in the assembled prism so that one constituent electric field component of the incident light experiences these matched indices of refraction. In addition, the liquid or other index matching medium is selected to have an index of refraction which is also substantially equal to the two matched indices of the prism materials. The single intermediate layer may be replaced with a sandwich of a plurality of intermediate layers. The composition of the plurality of intermediate layers alternates between the first and second birefringent or biaxial material with the outer layers being constructed from the second birefringent or biaxial material. In addition, the liquid or other index matching medium is used between each of this plurality of intermediate layers to provide optical coupling between each layer and the prism substrates. This prism configuration with a single or plurality of intermediate layers and the technique for choosing the prism materials provides the large angular aperture and, with the proper choice of materials, is operable substantially over the infrared, visible and ultraviolet spectrums.

Four element lens system

Abstract: A four element lens system for use on a camera and the like comprises two positive meniscus lens having two negative meniscus lens interposed between the positive lens The optical axis of each lens elements being aligned with an aperture stopper element or its functional equivalent between the negative lens elements The position of the effective plane of the aperture stopper satisfying the following equation: ##EQU1## wherein S is a distance along the optical axis between lens elements, S'2, is the distance between the surface of the second negative meniscus lens and the effective plane of the aperture stopper and S"2 is the distance between the effective plane of the aperture stopper and the surface of the third negative meniscus lens Preferably each of the lens elements is injection molded from a plastic material with both of the positive lens elements and the negative lens elements being identical lens As a result of the present invention, an image may be formed having relative low aberration from a portrait distance to a landscape distance in a camera that requires only the manufacture of two types of plastic lenses

Diffraction smoothing aperture for an optical beam

Abstract: The disclosure is directed to an aperture for an optical beam having an irregular periphery or having perturbations imposed upon the periphery to decrease the diffraction effect caused by the beam passing through the aperture. Such apertures are particularly useful with high power solid state laser systems in that they minimize the problem of self-focusing which frequently destroys expensive components in such systems.

Retrofocus wide angle lens system

Abstract: A retrofocus wide angle lens system provides an increased field angle with a large aperture ratio. Besides the specific arrangement of the individual lens components in the various embodiments of the present invention, the retrofocus wide angle lens design further satisfies the following conditions: ##EQU1## WHEREIN R IS THE RADII OF CURVATURES FOR THE SUCCESSIVE LENS SURFACES FROM THE OBJECT TO IMAGE SIDE OF THE LENS SYSTEM; N I and N II represent the refractive indices of lenses forming a cemented doublet on the image side of the diaphragm; R represents the common radius of curvature of an intermediate surface of the doublet and f represents the overall focal length of the lens system.

Scanning antenna with extended off broadside scanning capability

Abstract: An improved Lewis scanner comprising a focal lens having two best focus angles positioned with its axis at an angle other than perpendicular to the antenna aperture. The antenna aperture is maintained vertical with respect to the earth's surface to provide a planar beam at 0° elevation. The focal lens axis is oriented at an angle of typically one-half the maximum elevation scan angle. The angle of the microwave reflector between the parallel plates of the Lewis scanner is changed from the conventional 45° by one-half the angle between the focal lens axis and the 0° elevation angle. An asymmetric feed lens improves the beam shape over the entire scan range.

Compact lens system having a long back focal length and a large relative aperture

Abstract: A compact lens system comprising six components of seven lenses, having a long back focal length and a large relative aperture, favorably corrected in its aberrations, especially coma, and meeting the conditions enumerated below: f.sub.5 > f.sub.6, f.sub.7 > f.sub.6 1 0.7 < d.sub.8/d.sbsb.1.sbsb.0 < 0.8 2 0.18f < d.sub.7 + d.sub.8 + d.sub.9 + d.sub.10 < 0.22f n.sub.1, n.sub.2, n.sub.5 > 1.75 3

Retrofocus wide-angle objective lens system of large relative aperture

Abstract: A retrofocus wide-angle objective lens having a range of at least 75° with a large relative aperture and which is corrected for various aberrations and particularly curvature of field at the outer portions of the viewing field.

Retrofocus type lens system

Abstract: A retrofocus type lens system particularly useful for single lens reflex cameras. The back focal distance is 1.56 times as long as the effective focal length of the lens system and the angle of view is as large as 84°. The aperture ratio is as large as F/2.8 and all aberrations are well corrected. The lens system comprises a positive meniscus lens L1, two negative meniscus lenses L2 and L3 convex to the front, a positive meniscus lens or plano-convex lens L4 convex to the rear, a biconvex lens L5, a cemented negative lens component consisting of a biconcave lens L6 and a positive meniscus lens L7, a positive meniscus lens L8 convex to the rear, and a positive lens L9.