Topic
Angular aperture
About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.
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Patent•
04 Apr 1979
TL;DR: In this paper, an improved tesser type objective lens system with a rear aperture stop with a relatively wide field angle of about 60° and an F-number of about F 2.8 is provided.
Abstract: An improved tesser type objective lens system having a rear aperture stop with a relatively wide field angle of about 60° and an F-number of about F 2.8 is provided. The thickness of the second negative lens in the lens system is increased relative to the total axial distance of the lens system which permits the reduction of the Petzval sum while maintaining a balance correction of spherical aberration and coma.
4 citations
TL;DR: Based on the vectorial Debye theory, the focusing properties of the Gaussian beam through an annular high numerical aperture are studied numerically, including the intensity, the phase and the orbital angular momentum properties as mentioned in this paper.
Abstract: Based on the vectorial Debye theory, the focusing properties of the Gaussian beam through an annular high numerical aperture are studied numerically, including the intensity, the phase and the orbital angular momentum properties. Then the influence of certain parameters on the focusing properties is also investigated. It is shown that sub-wavelength elliptical light spots can be obtained. And there exists a vortex in the longitudinal component of the focused field even though the incident beam is Gaussian beam, indicating that the spin angular momentum of the elliptically polarized Gaussian beam is converted into the orbital angular momentum by the focusing.
4 citations
Patent•
04 Apr 2013TL;DR: In this article, a variable focal length achromatic lens with a pressure-controlled fluidic refractive lens and a flat binary Fresnel zone structure was used to produce high efficiency and millisecond switching times.
Abstract: A variable focal length achromatic lens includes a flat liquid crystal diffractive lens and a pressure-controlled fluidic refractive lens. The diffractive lens is composed of a flat binary Fresnel zone structure and a thin liquid crystal layer, producing high efficiency and millisecond switching times while applying a low ac voltage input. The focusing power of the diffractive lens is adjusted by electrically modifying the sub-zones and re-establishing phase wrapping points. The refractive lens includes a fluid chamber with a flat glass surface and an opposing elastic polydimethylsiloxane (PDMS) membrane surface. Inserting fluid volume through a pump system into the clear aperture region alters the membrane curvature and adjusts the refractive lens' focal position. Primary chromatic aberration is remarkably reduced through the coupling of the fluidic and diffractive lenses at a number of selected focal lengths. Potential applications include miniature color imaging systems, medical and ophthalmic devices, or any design that utilizes variable focal length achromats.
4 citations
01 May 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a reflecting system for focusing the radiation of a quasipoint X-ray source in the hard range of wavelengths (λ ⩽ 0.2 nm ) is proposed.
Abstract: A method for manufacturing a reflecting system for focussing the radiation of a quasipoint X-ray source in the hard range of wavelengths ( λ ⩽ 0.2 nm ) is proposed. The system consists of four identical multilayer mirrors having the form of an elliptical cylinder. Cylinder generatrixes of the adjoining mirrors are mutually perpendicular. The angular aperture of the system is Δ Ω = 5.8 × 1 0 - 4 steradian.
4 citations