نتایج جستجو برای: fresnel lenses
تعداد نتایج: 15913 فیلتر نتایج به سال:
A holographic projection system with optical zoom is demonstrated. By using a combination of a LC lens and an encoded Fresnel lens on the LCoS panel, we can control zoom in a holographic projector. The magnification can be electrically adjusted by tuning the focal length of the combination of the two lenses. The zoom ratio of the holographic projection system can reach 3.7:1 with continuous zoo...
The technology to focus hard-X-rays (photon energy larger than 1–2 keV) has made great progress in the past three years. The progress was particularly spectacular for lenses based on the Fresnel zone plate concept. The spatial resolution notably increased by a factor of three, opening up entirely new domains of application, specifically in biomedical research. As we shall see, this evolution is...
We analyse the possibilities of using a new kind of Bragg Fresnel Multilayer Lens that we have designed in order to improve image contrastIl1. We discuss the aberrations and the dynamical properties of this lens on the base of a recently developed dynamical theory[zI and of the data from the first imaging tests that we have performed. The principle of the optimal configuration for utilisation o...
A mathematical model describing the behavior of low-resolution Fresnel encoded lenses (LRFEL's) encoded in any low-resolution device (e.g., a spatial light modulator) has recently been developed. From this model, an LRFEL with a short focal length was optimized by our imposing the maximum intensity of light onto the optical axis. With this model, analytical expressions for the light-amplitude d...
We report on a numerical analysis method for diffractive optical elements that consist of features ranging from subwavelength to more than 10lambda. The essence of the method is treating local structures of the optical elements as diffraction gratings. It is shown that the method can provide accuracy of results comparable with fully electromagnetic treatments in much shorter time. The theory an...
Fresnel zone plates (450 nm thick Au, 25 nm outermost zone width) used as objective lenses in a full field transmission reached a spatial resolution better than 20 nm and 1.5% efficiency with 8 keV photons. Zernike phase contrast was also realized without compromising the resolution. These are very significant achievements in the rapid progress of high-aspect-ratio zone plate fabrication by com...
A three-dimensional multi-stage optical interconnection network is proposed for mussively purullel processors. The interconnection network employs beamsteering vertical cavity surface-emitting lasers FCSEL) as space-division switching elements, and micromachined micro-Fresnel lenses as free-space optical elements. The entire switching network is integrated on a Si chip using the free-space micr...
This paper presents a study on the use of optical fiber and a solar concentrator for a building daylighting system. Daylighting is essential for improving indoor environments and reducing electric lighting power consumption in office buildings. Traditionally, optical fiber daylighting systems were implemented only on a small scale. More complicated technologies are required for more amounts of ...
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