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Planar Fourier Capture Array
A planar Fourier capture array (PFCA) is a tiny camera that requires no mirror, lens, focal length, or moving parts. It is composed of angle-sensitive pixels, which can be manufactured in unmodified CMOS processes. Angle-sensitive pixels have a sensitivity to light that is sinusoidal in incident angle along the optically-sensitive axis, which can be interpreted as measuring one component of the 2D Fourier transform of the far-away scene. By making them all unique, each sensor of the PFCA relates a distinct component of the 2D Fourier transform of the far-away scene, and together they relate full Fourier information. Original images are reconstructed computationally after acquisition, or if raw Fourier coefficients are more useful for the application at hand, they are used directly. PFCAs do not perform an exact Fourier transform since outputs are real-valued and are not perfect sinusoidal transforms of the image. The transform is closer to a Hartley transform, but even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Micrograph Of The First Prototype PFCA
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization. Its speed in a vacuum, 299 792 458 metres a second (m/s), is one of the fundamental constants of nature. Like all types of electromagnetic radiation, visible light propagates by massless elementary particles called photons that represents the quanta of electromagnetic field, and can be analyzed as both waves and particl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reconstruction Of The Mona Lisa Based On Outputs Of The First Prototype PFCA
Reconstruction may refer to: Politics, history, and sociology *Reconstruction (law), the transfer of a company's (or several companies') business to a new company *'' Perestroika'' (Russian for "reconstruction"), a late 20th century Soviet Union political movement *Critical reconstruction, an architectural theory related to the reconstruction of Berlin after the end of the Berlin Wall *Economic reconstruction * Ministry of Reconstruction, a UK government department *The Reconstruction era of the United States, the period after the Civil War, 1865–1877 ** The Reconstruction Acts, or Military Reconstruction Acts, addressing requirements for Southern States to be readmitted to the Union * Reconstruction Finance Corporation, a United States government agency from 1932–1957 Arts, entertainment, and media Films * ''Reconstruction'' (1968 film), a Romanian tragicomedy * ''Reconstruction'' (2001 film), about the 1959 Ioanid Gang bank heist in Romania * ''Reconstruction'' (2003 film ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle-sensitive Pixel
An angle-sensitive pixel (ASP) is a CMOS sensor with a sensitivity to incoming light that is sinusoidal in incident angle. Principles of operation ASPs are typically composed of two gratings (a diffraction grating and an analyzer grating) above a single photodiode. ASPs exploit the moire effect and the Talbot effect to gain their sinusoidal light sensitivity. According to the moire effect, if light acted as a particle, at certain incident angles the gaps in the diffraction and analyzer gratings line up, while at other incident angles light passed by the diffraction grating is blocked by the analyzer grating. The amount of light reaching the photodiode would be proportional to a sinusoidal function of incident angle, as the two gratings come in and out of phase with each other with shifting incident angle. The wave nature of light becomes important at small scales such as those in ASPs, meaning a pure-moire model of ASP function is insufficient. However, at half-integer multip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors (CMOS sensors), data converters, RF circuits (RF CMOS), and highly integrated transceivers for many types of communication. The CMOS process was originally conceived by Frank Wanlass at Fairchild Semiconductor and presented by Wanlass and Chih-Tang Sah at the International Solid-State Circuits Conference in 1963. Wanlass later filed US patent 3,356,858 for CMOS circuitry and it was granted in 1967. commercialized the technology with the trademark "COS-MO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle-sensitive Pixel
An angle-sensitive pixel (ASP) is a CMOS sensor with a sensitivity to incoming light that is sinusoidal in incident angle. Principles of operation ASPs are typically composed of two gratings (a diffraction grating and an analyzer grating) above a single photodiode. ASPs exploit the moire effect and the Talbot effect to gain their sinusoidal light sensitivity. According to the moire effect, if light acted as a particle, at certain incident angles the gaps in the diffraction and analyzer gratings line up, while at other incident angles light passed by the diffraction grating is blocked by the analyzer grating. The amount of light reaching the photodiode would be proportional to a sinusoidal function of incident angle, as the two gratings come in and out of phase with each other with shifting incident angle. The wave nature of light becomes important at small scales such as those in ASPs, meaning a pure-moire model of ASP function is insufficient. However, at half-integer multip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier Transform
A Fourier transform (FT) is a mathematical transform that decomposes functions into frequency components, which are represented by the output of the transform as a function of frequency. Most commonly functions of time or space are transformed, which will output a function depending on temporal frequency or spatial frequency respectively. That process is also called ''analysis''. An example application would be decomposing the waveform of a musical chord into terms of the intensity of its constituent pitches. The term ''Fourier transform'' refers to both the frequency domain representation and the mathematical operation that associates the frequency domain representation to a function of space or time. The Fourier transform of a function is a complex-valued function representing the complex sinusoids that comprise the original function. For each frequency, the magnitude (absolute value) of the complex value represents the amplitude of a constituent complex sinusoid with that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartley Transform
In mathematics, the Hartley transform (HT) is an integral transform closely related to the Fourier transform (FT), but which transforms real-valued functions to real-valued functions. It was proposed as an alternative to the Fourier transform by Ralph V. L. Hartley in 1942, and is one of many known Fourier-related transforms. Compared to the Fourier transform, the Hartley transform has the advantages of transforming real functions to real functions (as opposed to requiring complex numbers) and of being its own inverse. The discrete version of the transform, the discrete Hartley transform (DHT), was introduced by Ronald N. Bracewell in 1983. The two-dimensional Hartley transform can be computed by an analog optical process similar to an optical Fourier transform (OFT), with the proposed advantage that only its amplitude and sign need to be determined rather than its complex phase. However, optical Hartley transforms do not seem to have seen widespread use. Definition The Hartley tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charge-coupled Device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras, act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Pixel Sensor
An active-pixel sensor (APS) is an image sensor where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors. In a metal–oxide–semiconductor (MOS) active-pixel sensor, MOS field-effect transistors (MOSFETs) are used as amplifiers. There are different types of APS, including the early NMOS APS and the now much more common complementary MOS (CMOS) APS, also known as the CMOS sensor. CMOS sensors are used in digital camera technologies such as cell phone cameras, web cameras, most modern digital pocket cameras, most digital single-lens reflex cameras (DSLRs), and mirrorless interchangeable-lens cameras (MILCs). CMOS sensors emerged as an alternative to charge-coupled device (CCD) image sensors and eventually outsold them by the mid-2000s decade. The term ''active pixel sensor'' is also used to refer to the individual pixel sensor itself, as opposed to the image sensor. In this case, the image sensor is sometimes c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superlens
A superlens, or super lens, is a lens (optics), lens which uses metamaterials to go beyond the diffraction limit. For example, in 1995, Guerra combined a transparent grating having 50nm lines and spaces (the "metamaterial") with a conventional microscope immersion objective. The resulting "superlens" resolved a silicon sample also having 50nm lines and spaces, far beyond the classical diffraction limit imposed by the illumination having 650nm wavelength in air. The diffraction limit is a feature of conventional lenses and optical microscopy, microscopes that limits the fineness of their resolution depending on the illumination wavelength and the numerical aperture NA of the objective lens. Many lens designs have been proposed that go beyond the diffraction limit in some way, but constraints and obstacles face each of them. History In 1873 Ernst Abbe reported that conventional lenses are incapable of capturing some fine details of any given image. The super lens is intended to cap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier Analysis
In mathematics, Fourier analysis () is the study of the way general functions may be represented or approximated by sums of simpler trigonometric functions. Fourier analysis grew from the study of Fourier series, and is named after Joseph Fourier, who showed that representing a function as a sum of trigonometric functions greatly simplifies the study of heat transfer. The subject of Fourier analysis encompasses a vast spectrum of mathematics. In the sciences and engineering, the process of decomposing a function into oscillatory components is often called Fourier analysis, while the operation of rebuilding the function from these pieces is known as Fourier synthesis. For example, determining what component frequencies are present in a musical note would involve computing the Fourier transform of a sampled musical note. One could then re-synthesize the same sound by including the frequency components as revealed in the Fourier analysis. In mathematics, the term ''Fourier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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