Topic
Spatial cutoff frequency
About: Spatial cutoff frequency is a research topic. Over the lifetime, 18 publications have been published within this topic receiving 684 citations.
Papers
TL;DR: In this article, the spatial bandwidth of an optical system can be increased over the classical limit by reducing one of the other constituent factors of N. This invariance theorem was established in Part I of this series [J. Opt. Soc. Am.56, 1463].
Abstract: The fundamental invariant of an optical system is the number N of degrees of freedom of the message it can transmit. The spatial bandwidth of the system can be increased over the classical limit by reducing one of the other constituent factors of N. As examples of this invariance theorem N=const. established in Part I of this series [ J. Opt. Soc. Am.56, 1463 ( 1966)], we discuss (a) a system whose spatial-bandwidth increase is achieved by a proportional reduction of its temporal bandwidth, and (b) the airborne synthetic-aperture, terrain-mapping radar, whose spatial resolution comes from exploitation of the temporal degrees of freedom of the received signal. The increase of the spatial bandwidth beyond the classical limit is, however, limited by the appearance of evanescent waves.The number of degrees of freedom of the object wave field stored in a hologram is discussed. The storage capacity of the photographic plate, which is proportional to its size times its spatial cutoff frequency, is fully exploited only by single-sideband Fraunhofer but not by single-sideband Fresnel holograms.
460 citations
TL;DR: A new configuration for the Polar Stratospheric Telescope primary is proposed, using the practical cutoff frequency rather than the traditional cutoff frequency, as the more useful frequency for the detection of details.
Abstract: We analyze the imaging performance of a number of diluted-aperture configurations, using the modulation transfer function. We select a single figure of merit, the practical cutoff frequency, rather than the traditional cutoff frequency, as the more useful frequency for the detection of details. Using this new parameter, we compare the performance of a number of published aperture configurations. On the basis of this analysis a new configuration is proposed for the Polar Stratospheric Telescope primary.
38 citations
Patent•
28 May 1991TL;DR: In this paper, the tracking control on an optical disc whose recording tracks are arragnged at a high density that exceeds the spatial cutoff frequency of an optical system of conventional nature is presented.
Abstract: n pairs of light beams are applied to an optical disc (D) to form a plurality of beam spots (SP) thereon which are offset by 1/2n of a track pitch p, and n signals which are shifted p/2n in spatial phase are generated from detected output signals indicative of light beams reflected from the beam spots (SP). These n signals are multiplied to produce a tracking control signal whose spatial period is 1/n of the track pitch p. Alternatively, the optical disc has n pairs of wobbling pits or servo pits which are offset by 1/2n of a tracking pitch p are disposed on an optical disc, and the n pairs of servo pits are scanned by a light beam to produce n signals that are shifted p/2n in spatial phase. The tracking control method is effective to effect tracking control on an optical (D) disc whose recording tracks are arragnged at a high density that exceeds the spatial cutoff frequency of an optical system of conventional nature used with the tracking control method.
35 citations
Patent•
12 Jan 1995
TL;DR: In this paper, a tracking error signal is obtained through multiplication of differential signals obtained at the timing of Sa1 and Sa2, and the signal can be detected up to a spatial cutoff frequency twice as high as the frequency in the conventional case by means of a conventional optical system.
Abstract: Disclosed is an optical data apparatus for recording and regenerating data on an optical disc, optical card, or the like. There are particularly disclosed an optical data apparatus and an optical data storage medium appropriate for the apparatus capable of detecting a tracking error signal effective particularly for an optical data storage medium on which optical data are recorded at a high density. A pattern is formed on a track and in a position displaced from the track by half cycle of the track in a first servo pattern area, and no pattern is formed in a second servo pattern area. The first servo pattern area and the second servo pattern area are arranged adjacent to each other. The tracking error signal is obtained through multiplication of differential signals obtained at the timing of Sa1 and Sa2. The tracking error signal can be detected up to a spatial cutoff frequency twice as high as the frequency in the conventional case by means of a conventional optical system.
14 citations
Patent•
30 Jul 1993TL;DR: In this article, a tracking error signal is obtained through multiplication of differential signals obtained at the timing of Sa1 and Sa2, and the signal can be detected up to a spatial cutoff frequency twice as high as the frequency in the conventional case by means of a conventional optical system.
Abstract: Disclosed is an optical data apparatus for recording and regenerating data on an optical disc, optical card, or the like. There are particularly disclosed an optical data apparatus and an optical data storage medium appropriate for the apparatus capable of detecting a tracking error signal effective particularly for an optical data storage medium on which optical data are recorded at a high density. A pattern is formed on a track and in a position displaced from the track by half cycle of the track in a first servo pattern area, and no pattern is formed in a second servo pattern area. The first servo pattern area and the second servo pattern area are arranged adjacent to each other. The tracking error signal is obtained through multiplication of differential signals obtained at the timing of Sa1 and Sa2. The tracking error signal can be detected up to a spatial cutoff frequency twice as high as the frequency in the conventional case by means of a conventional optical system.
11 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2020 | 2 |
| 2019 | 1 |
| 2018 | 1 |
| 2017 | 1 |
| 2013 | 1 |