Topic
Diffraction efficiency
About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.
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TL;DR: The third-order aberrations of a diffractive optical element with paraxial zone spacings are derived as a function of aperture stop position and the distortion of the resulting system is shown to be the proper amount for use as a Fourier transform lens.
Abstract: The third-order aberrations of a diffractive optical element with paraxial zone spacings are derived as a function of aperture stop position. It is shown that by placing the stop in the front focal plane, coma and astigmatism are identically zero, assuming an infinitely distant object. In addition, since the element is diffractive, the Petzval sum is also zero. Modulation transfer function comparisons with other lenses are given. The correction of spherical aberration using an aspheric plate located in the aperture stop and nonmonochromatic imaging performance are discussed. The distortion of the resulting system is shown to be the proper amount for use as a Fourier transform lens. An estimate for the space-bandwidth product of this Fourier transform system is given.
82 citations
Patent•
21 Apr 1995TL;DR: In this article, an electro-optical head is used to detect the presence or absence of a holographic grating at any one of these plural locations, which can be used as an indicator of the value of the stored data element.
Abstract: An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created at plural locations within the disk. An electro-optical head which is capable of creating these holographic gratings at any one of the plural locations is employed. The head is additionally capable of detecting the presence or absence of a holographic grating at any one of these plural locations. The presence of the holographic grating could indicate a first binary state and the absence of the holographic grating indicate a second state. Alternately, the electro-optical head could be used to vary the diffraction efficiency of the holographic gratings during their creation. In that case, the head would also be capable of detecting this variation in efficiency and produce a proportional detection signal. This signal would be used as an indicator of the value of the stored data element. The material of the optical disk is further capable of having multiple holographic gratings created at each one of the plural locations. These multiple holographic gratings are created via a beam of light from the electro-optical head which has a different wavelength or point of focus. In reading these holographic gratings, a beam of light generated by the electro-optical head is sequentially varied in wavelength or point of focus to correspond to the wavelength or point of focus and the sequence of wavelengths or points of focus employed to record each one of the data elements recorded.
82 citations
TL;DR: In this article, a microrubbing process was proposed to generate a very fine liquid crystal alignment pattern using a metal ball and the thickness of the line thickness was controlled by the normal load.
Abstract: A novel rubbing process for generating a very fine liquid crystal (LC) alignment pattern is proposed: we term this the "microrubbing process". An alignment film (polyimide) is rubbed using a metal ball and the thicknesses of rubbed lines are controlled by the normal load. It is described that the maximum line thickness is restricted by the ball diameter and thickness of the alignment film. An LC grating with homogenous and twisted-nematic orientation domains is proposed and is successfully fabricated using the microrubbing process. Polarization-independent diffraction efficiency is confirmed in the low applied-voltage region below the threshold voltage of the electro-optical effect and the high applied-voltage region above 2 V. The diffraction efficiency almost reaches the theoretically maximum value at an optimum applied voltage and is electrically controllable while maintaining polarization-independent diffraction properties.
82 citations
Patent•
12 Nov 2004
TL;DR: In this article, an apparatus and a method of printing a diffraction grating was described. But the present paper relates to diffraction gratings applied to a substrate (1), such as a hologram.
Abstract: There is provided an apparatus and a method of printing a diffraction grating. In particular, the present invention relates to diffraction gratings applied to a substrate (1), such as a hologram.
82 citations
TL;DR: In this paper, a review and comparison of design procedures for binary-phase and multiphase Fourier gratings used as array generators is presented, and examples of grating design using the different techniques are presented.
Abstract: A review and comparison of design procedures for binary-phase and multiphase Fourier gratings used as array generators is presented. Grating structures include one- and two-dimensional binary-phase Dammann gratings, general binary-phase gratings, quarternary-phase Dammann gratings, and kinoforms for which coherent and incoherent designs are considered. One coherent method of design is that due to Dammann, which involves the solution of a set of N nonlinear equations in N unknowns. Although Dammann’s method generates little error, it does not permit the explicit maximization of diffraction efficiency. To increase diffraction efficiency, Dammann’s method is modified such that diffraction efficiency is a design parameter. To ensure the existence of a grating that has high diffraction and generates the desired source array, the number of grating parameters are increased, and an incoherent design is considered. Simulated annealing is applied to the solution of this problem. Examples of grating design using the different techniques are presented.
82 citations