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Coded Aperture
Coded apertures or coded-aperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation. The wavelengths are usually high-energy radiation such as X-rays and gamma rays. By blocking radiation in a known pattern, a coded "shadow" is cast upon a plane. The properties of the original radiation sources can then be mathematically reconstructed from this shadow. Coded apertures are used in X- and gamma ray imaging systems, because these high-energy rays cannot be focused with lenses or mirrors that work for visible light. Rationale Imaging is usually done at optical wavelengths using lenses and mirrors. However, the energy of hard X-rays and γ-rays is too high to be reflected or refracted, and simply passes through the lenses and mirrors of optical telescopes. Image modulation by apertures is therefore often used instead. The pinhole camera is the most basic form of such a modulation imager, but its disadvantage is low th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optimized RAndom Pattern
Mathematical optimization is the theory and computation of extrema or stationary points of functions. Optimization, optimisation, or optimality may also refer to: * Engineering optimization * Feedback-Directed Optimisation, in computing * Optimality model in biology * Optimality Theory, in linguistics * Optimization (role-playing games), a gaming play style * ''Optimize'' (magazine) * Process optimization, in business and engineering, methodologies for improving the efficiency of a production process * Product optimization, in business and marketing, methodologies for improving the quality and desirability of a product or product concept * Program optimization, in computing, methodologies for improving the efficiency of software * Search engine optimization, in internet marketing *Supply chain optimization, a methodology aiming to ensure the optimal operation of a manufacturing and distribution supply chain See also * Optimum (other) * Optimality theory (disambiguat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deconvolution
In mathematics, deconvolution is the operation inverse to convolution. Both operations are used in signal processing and image processing. For example, it may be possible to recover the original signal after a filter (convolution) by using a deconvolution method with a certain degree of accuracy. Due to the measurement error of the recorded signal or image, it can be demonstrated that the worse the SNR, the worse the reversing of a filter will be; hence, inverting a filter is not always a good solution as the error amplifies. Deconvolution offers a solution to this problem. The foundations for deconvolution and time-series analysis were largely laid by Norbert Wiener of the Massachusetts Institute of Technology in his book ''Extrapolation, Interpolation, and Smoothing of Stationary Time Series'' (1949). The book was based on work Wiener had done during World War II but that had been classified at the time. Some of the early attempts to apply these theories were in the fields of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Photography
Computational photography refers to digital image capture and processing techniques that use digital computation instead of optical processes. Computational photography can improve the capabilities of a camera, or introduce features that were not possible at all with film based photography, or reduce the cost or size of camera elements. Examples of computational photography include in-camera computation of digital panoramas, high-dynamic-range images, and light field cameras. Light field cameras use novel optical elements to capture three dimensional scene information which can then be used to produce 3D images, enhanced depth-of-field, and selective de-focusing (or "post focus"). Enhanced depth-of-field reduces the need for mechanical focusing systems. All of these features use computational imaging techniques. The definition of computational photography has evolved to cover a number of subject areas in computer graphics, computer vision, and applied optics. These areas are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RHESSI
Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI, originally High Energy Solar Spectroscopic Imager or HESSI or Explorer 81) was a NASA solar flare observatory. It was the sixth mission in the Small Explorer program (SMEX), selected in October 1997 and launched on 5 February 2002, at 20:58:12 UTC. Its primary mission was to explore the physics of particle acceleration and energy release in solar flares. Spacecraft HESSI was renamed to RHESSI on 29 March 2002 in honor of Dr. Ramaty, a pioneer in the area of high energy solar physics. RHESSI was the first space mission named after a NASA scientist. RHESSI was built by Spectrum Astro for Goddard Space Flight Center and was operated by the Space Sciences Laboratory in Berkeley, California. The principal investigator from 2002 to 2012 was Robert Lin, who was succeeded by Säm Krucker. The entire spacecraft rotated to provide the necessary signal modulation. The four, fixed solar panels were designed to provide enou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Third Small Astronomy Satellite
The Small Astronomy Satellite 3 (SAS 3, also known as SAS-C before launch) was a NASA X-ray astronomy space telescope. It functioned from May 7, 1975 to April 1979. It covered the X-ray range with four experiments on board. The satellite, built by the Johns Hopkins University Applied Physics Laboratory (APL), was proposed and operated by MIT's Center for Space Research (CSR). It was launched on a Scout vehicle from the Italian San Marco launch platform near Mombasa, Kenya, into a low-Earth, nearly equatorial orbit. It was also known as Explorer 53, as part of NASA's Explorer program. The spacecraft was 3-axis stabilized with a momentum wheel that was used to establish stability about the nominal rotation, or z-axis. The orientation of the z-axis could be altered over a period of hours using magnetic torque coils that interacted with the Earth's magnetic field. Solar panels charged batteries during the daylight portion of each orbit, so that SAS 3 had essentially no expendab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Variable Objects Monitor
The Space Variable Objects Monitor (SVOM) is a planned small X-ray telescope satellite under development by China National Space Administration (CNSA), Chinese Academy of Sciences (CAS) and the French Space Agency (CNES), to be launched in the spring of 2024. SVOM will study the explosions of massive stars by analysing the resulting gamma-ray bursts. The light-weight X-ray mirror for SVOM weighs just . SVOM will add new capabilities to the work of finding gamma-ray bursts currently being done by the multinational satellite ''Swift Gamma-Ray Burst Mission''. Its anti-solar pointing strategy makes the Earth cross the field of view of its payload every orbit. Objectives Using synergy between space and ground instruments, the mission has these scientific objectives: * Permit the detection of all known types of Gamma-ray bursts (GRB) * Provide fast, reliable GRB positions * Measure the Electromagnetic spectrum, broadband spectral shape of the prompt emission (from visible to MeV) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrosat
''Astrosat'' is India's first dedicated multi-wavelength space telescope. It was launched on a PSLV-XL on 28 September 2015. With the success of this satellite, ISRO has proposed launching '' AstroSat-2'' as a successor for ''Astrosat''.Isro plans to launch India's 2nd space observatory Times of India 19 February 2018 Overview After the success of the satellite-borne (IXAE), which was launched in 1996, the |
Ultra-Fast Flash Observatory Pathfinder
The Ultra-Fast Flash Observatory (UFFO) Pathfinder is a space observatory measuring prompt emission of gamma-ray bursts (GRB) both in optical/UV and in X-ray range down to sub-second timescales for the first time. Instead of turning the whole satellite towards GRB location like the Swift Gamma-Ray Burst Mission (that takes about 100 seconds), UFFO employs a slewing mirror telescope approach – the optical path of the telescope is changed by rotation of motorized mirror within ~1 second after burst was detected. UFFO was launched April 28, 2016 on board the Mikhailo Lomonosov satellite during the first launch from the new Russian Vostochny Cosmodrome. Instruments UFFO Burst Alert & Trigger telescope (UBAT) UBAT is a wide-field coded mask X-ray camera. It has a 191 cm2 detecting area, 90.2°×90.2° field of view and is sensitive in the 15-150 keV photon energy range. UBAT is able to localize bursts with an accuracy of 7σ to a region 10 arcmin across in less than one seco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swift Gamma-Ray Burst Mission
Neil Gehrels Swift Observatory, previously called the Swift Gamma-Ray Burst Explorer, is a NASA three-telescope space observatory for studying gamma-ray bursts (GRBs) and monitoring the afterglow in X-ray, and UV/Visible light at the location of a burst. It was launched on 20 November 2004, aboard a Delta II launch vehicle. Headed by principal investigator Neil Gehrels until his death in February 2017, the mission was developed in a joint partnership between Goddard Space Flight Center (GSFC) and an international consortium from the United States, United Kingdom, and Italy. The mission is operated by Pennsylvania State University as part of NASA's Medium Explorer program (MIDEX). The burst detection rate is 100 per year, with a sensitivity ~3 times fainter than the BATSE detector aboard the Compton Gamma Ray Observatory. The Swift mission was launched with a nominal on-orbit lifetime of two years. Swift is a NASA MIDEX (medium-class Explorer) mission. It was the third to be lau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
INTEGRAL
In mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ..., an integral assigns numbers to functions in a way that describes Displacement (geometry), displacement, area, volume, and other concepts that arise by combining infinitesimal data. The process of finding integrals is called integration. Along with Derivative, differentiation, integration is a fundamental, essential operation of calculus,Integral calculus is a very well established mathematical discipline for which there are many sources. See and , for example. and serves as a tool to solve problems in mathematics and physics involving the area of an arbitrary shape, the length of a curve, and the volume of a solid, among others. The integrals enumerated here are those termed definite integrals, which can be int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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