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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TL;DR: In this article, an acousto-optic interaction geometry in a uniaxial crystal is described, which uses acoustic beam steering to couple incident and diffracted optical beams with parallel group velocities.
Abstract: We describe an acousto-optic interaction geometry in a uniaxial crystal which uses acoustic beam steering to couple incident and diffracted optical beams with parallel group velocities. The device uses tangential acoustic beam steering to provide large RF bandwidths at high efficiency. As with the acoustooptic tunable filter, the choice of parallel optic group velocities provides for a large input angular aperture, useful in multiplicative optical processing architectures. The parallel optical group velocities and beam steering geometry allow use of the Bragg cell with optical beams propagating in close proximity to the transducer, eliminating the dead time which is crucial in correlation cancelation feedback optical processors. The wide angular aperture allows this same interaction geometry to be used for high-efficiency wide- band acoustooptic modulators as well.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
5 citations
TL;DR: An optical head using a single objective lens for Blu-ray disc (BD), HD DVD, digital versatile disc (DVD), and compact disc (CD) has been developed, which is suitable for high-speed recording and reading as discussed by the authors.
Abstract: An optical head using a single objective lens for Blu-ray disc (BD), high-density digital versatile disc (HD DVD), digital versatile disc (DVD), and compact disc (CD) has been developed, which is suitable for high-speed recording and reading. A relay lens unit, which consists of two convex lenses and one concave lens, corrects the spherical aberration and realizes high light power efficiency for each disk. A numerical aperture (NA) control element, which contains a liquid crystal aperture and a wavelength selective aperture, controls the NA of the objective lens for each disk. A coma aberration caused by the objective lens shift is detected based on differential phase detection signals for read-only disks and push–pull signals for recordable or rewritable disks, and is corrected by moving one of the lenses in the relay lens unit by an actuator. A diffraction-limited focused spot and good readout signal characteristics were obtained for each disk, and the validity of this optical design has been demonstrated.
5 citations
Patent•
22 Aug 1998TL;DR: In this paper, a charged particle beam projection system includes a source of charged particles and a first doublet of condenser lenses with a first symmetry plane through which the beam is directed, located lower on the column.
Abstract: A charged particle beam projection system includes a source of charged particles and a first doublet of condenser lenses with a first symmetry plane through which the beam is directed, located lower on the column. A trim aperture element is located at the first symmetry plane of the first doublet wherein the trim aperture serves as a first blanking aperture. Below the trim aperture there is a shaping aperture. Next is a second doublet of condenser lenses with a second symmetry plane. A third aperture, which is located at the symmetry plane of the second doublet serves as another blanking aperture.
5 citations
TL;DR: In this paper, a diffractive-refractive lens with an aperture diameter of 120 mm has been designed, fabricated, and demonstrated for the sub-millimeter focal plane imaging system.
Abstract: To reduce transmission loss and improve spatial resolution, a diffractive-refractive lens with an aperture diameter of 120 mm has been designed, fabricated, and demonstrated for the submillimeter focal plane imaging system. We analyze the lens’ characteristics, such as focal length, depth of focus, beams spot size, spatial resolution, and field of view, theoretically and experimentally. It is the first time this is used as a focusing lens in the submillimeter wave imaging system. The results show that the lens’ characteristics are identical with theoretical analysis.
5 citations
TL;DR: In this paper, a new type of acousto-optic (AO) modulator with enhanced performance is described, which uses phased array transducers in a birefringent AO cell, and achieves both large bandwidth and angular aperture.
Abstract: A new type of acousto-optic (AO) modulator with enhanced performance is described. By using phased array transducers in a birefringent AO cell, it is possible to simultaneously satisfy the tangential and noncritical phase matching conditions and achieve both large bandwidth and angular aperture. The new design is optimum for modulators and low resolution deflectors with the important advantage of fast input optics.
5 citations