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This module describes the application of compressive sensing to the design of a novel imaging architecture called the "single-pixel camera".


Several hardware architectures have been proposed that apply the theory of compressive sensing (CS) in an imaging setting  [link] , [link] , [link] . We will focus on the so-called single-pixel camera   [link] , [link] , [link] , [link] , [link] . The single-pixel camera is an optical computer that sequentially measures the inner products y [ j ] = x , φ j between an N -pixel sampled version of the incident light-field from the scene under view (denoted by x ) and a set of N -pixel test functions { φ j } j = 1 M . The architecture is illustrated in [link] , and an aerial view of the camera in the lab is shown in [link] . As shown in these figures, the light-field is focused by a lens (Lens 1 in [link] ) not onto a CCD or CMOS sampling array but rather onto a spatial light modulator (SLM). An SLM modulates the intensity of a light beam according to a control signal. A simple example of a transmissive SLM that either passes or blocks parts of the beam is an overhead transparency. Another example is a liquid crystal display (LCD) projector.

Single-pixel camera block diagram. Incident light-field (corresponding to the desired image x ) is reflected off a digital micromirror device (DMD) array whose mirror orientations are modulated according to the pseudorandom pattern φ j supplied by a random number generator. Each different mirror pattern produces a voltage at the single photodiode that corresponds to one measurement y [ j ] .

The Texas Instruments (TI) digital micromirror device (DMD) is a reflective SLM that selectively redirects parts of the light beam. The DMD consists of an array of bacterium-sized, electrostatically actuated micro-mirrors, where each mirror in the array is suspended above an individual static random access memory (SRAM) cell. Each mirror rotates about a hinge and can be positioned in one of two states ( ± 10 degrees from horizontal) according to which bit is loaded into the SRAM cell; thus light falling on the DMD can be reflected in two directions depending on the orientation of the mirrors.

Each element of the SLM corresponds to a particular element of φ j (and its corresponding pixel in x ). For a given φ j , we can orient the corresponding element of the SLM either towards (corresponding to a 1 at that element of φ j ) or away from (corresponding to a 0 at that element of φ j ) a second lens (Lens 2 in [link] ). This second lens collects the reflected light and focuses it onto a single photon detector (the single pixel) that integrates the product of x and φ j to compute the measurement y [ j ] = x , φ j as its output voltage. This voltage is then digitized by an A/D converter. Values of φ j between 0 and 1 can be obtained by dithering the mirrors back and forth during the photodiode integration time. By reshaping x into a column vector and the φ j into row vectors, we can thus model this system as computing the product y = Φ x , where each row of Φ corresponds to a φ j . To compute randomized measurements, we set the mirror orientations φ j randomly using a pseudorandom number generator, measure y [ j ] , and then repeat the process M times to obtain the measurement vector y .

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
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The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
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a perfect square v²+2v+_
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algebra 2 Inequalities:If equation 2 = 0 it is an open set?
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or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
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Kristine 2*2*2=8
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Differences Between Laspeyres and Paasche Indices
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No. 7x -4y is simplified from 4x + (3y + 3x) -7y
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. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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silver nanoparticles could handle the job?
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I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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Source:  OpenStax, Introduction to compressive sensing. OpenStax CNX. Mar 12, 2015 Download for free at http://legacy.cnx.org/content/col11355/1.4
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