نتایج جستجو برای: diffraction gratings
تعداد نتایج: 71674 فیلتر نتایج به سال:
مسئله پخش امواج الکترومغناطیسی بوسیله شبکه ها و تعیین ضرایب برگشت و همچنین چگونگی انتقال و اندازه دامنه امواج برگشتی از مدتها قبل مورد توجه بوده و تحقیقاتی در این باره انجام شده است . جالب بودن مسئله بعلت برتری عملکرد شبکه های انکسار نسبت به منشور در اسپکتروسکوپی است . این برتری شامل قدرت تجربه بیشتر، اتلاف کمتر و همچنین امکان استفاده شبکه های انکسار در فرکانسهای مادون قرمز و ماوراء بنفش میباشد...
Diffraction gratings are used in optical communications devices, spectrographs, optical scanners, monochromators, and in other instances. Diffraction gratings are either transmission or reflection. Reflective gratings are, usually, either ruled or holographic. Blazed gratings (step-echelette or phase gratings) are non-planar gratings. We present the fabrication of blazed diffraction gratings us...
Transmission gratings that combine a large diffraction angle with a high diffraction efficiency and a low angular and wavelength dispersion could be used to collect sunlight in a light guide. In this paper we compare the diffractive properties of polarization gratings and classical surface-relief gratings and explore their possible use in solar concentrators. It is found that polarization grati...
Measurements of the diffraction characteristics of one-dimensional surface-relief gratings of locally varying profile are compared with rigorous diffraction theory. These gratings result from the superposition of two linear sinusoidal gratings of uniform depth for which the relative phase between the two gratings varies slowly with position. The resultant surface profile exhibits a relatively l...
The main conditions and parameters for obtaining surface relief total internal reflection diffraction gratings in conical mounting are presented. Calculated and experimental investigations reveal that there are ranges of grating periods, incidence angles, diffraction angles and gratings depths for which such gratings could be obtained, both for TE and TM polarizations. With optimized grating pa...
Diffraction gratings were believed to be a rare cause of colour in nature. However, surface gratings, which include diffraction gratings and Bragg gratings, appear to occur in many forms within a diversity of animals. Structural colours in general have implications in the study of animal behaviour and evolution.
Nanofabricated transmission gratings for electron diffraction are now available [1, 2] and may serve as coherent beam splitters for electron interferometry just as they already do for atom interferometry. For electron beams with kinetic energy less than 10 keV, nanostructures offer several advantages over solid crystal gratings, for example larger transmission, less inelastic scattering, and th...
We report on the ultrafast laser inscription (ULI) of volume phase gratings inside gallium lanthanum sulphide (GLS) chalcogenide glass substrates. The effect of laser pulse energy and grating thickness on the dispersive properties of the gratings is investigated, with the aim of improving the performance of the gratings in the mid-infrared. The grating with the optimum performance in the mid-in...
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