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Problem statement

The ability to image sketches hidden by layers of paint is a valuable asset to art purchasers in their attempts toexhaustively examine the works they collect. Art conservators value a painting's underdrawings for two main reasons. The firstis that underdrawings can be exploited as an aid in determining whether the painting is an original or a forgery, by comparingthe style of the underdrawings to those of an artist's other works. The second is that comparisons between a painting and itsown underdrawing can give new insights into an artist's creative process for that work of art. Underdrawing images are bestrevealed by near infrared (NIR) cameras because all paint pigments, except black, are somewhat transparent in the 900 - 1700 nm range . However, current NIR cameras that are sensitive in this wavelength range are exorbitantlyexpensive, typically costing around $50,000 . This leaves the market of small art museums and individual artcollectors unaddressed. We intend to deliver an NIR camera that meets or exceeds key imaging system parameters in this market,such as spectral range, image resolution, capture time, and portability, while also reducing cost below the $5,000 level.

Background

Before the 1960s, there was only one way to examine a painting's underdrawing: the layers of paint in front of the underdrawing had tobe removed, thereby destroying the painting in the process. This was unacceptable for multiple reasons. Since underdrawings are typicallyof less interest than the finished painting, removing the layers of paint on top is not justified. Also, many interesting results comefrom a detailed comparison between the original painting and its underdrawing. This comparison is difficult if the paint layers mustbe destroyed to access the underdrawing.

J. R. J. van Asperen de Boer was the first to image underdrawings using NIR reflectography in 1968 . Previous attempts had used an NIR camera to passively capture light inthat range. However, with passive capture it was difficult to see through pigments such as green, since most of the lightcollected was in the range of 750 - 900 nm, which is below the range where those colors are transparent. Boer solved thisproblem by capturing the reflected light from a tungsten lamp that produced radiation of wavelengths up to 2500 nm, giving amuch clearer image of the underdrawing. While Boer's design has been improved in numerous ways during the past four decades, itremains fundamental to most techniques for imaging underdrawings nondestructively.

and below are examples of comparisons between original paintings and their underdrawings ascaptured with a typical modern NIR camera. In , the underdrawing shows that the man in the top hat, the artist'saccountant, was initially looking towards the viewer, but later this changed so that he looked away, purportedly because ofdisagreements between the two men . In , a large arrow can be seen on the chest of a horse on the underdrawing of a painting by Laib. This arrow is absentfrom the overlaid painted image.

Questions & Answers

so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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Cied
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Damian Reply
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Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
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Yasmin
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Cesar
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Uday
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what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
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AMJAD
what is system testing
AMJAD
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Stotaw
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
Azam
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Prasenjit
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Azam
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Prasenjit
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Damian
silver nanoparticles could handle the job?
Damian
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Azam
Hello
Uday
I'm interested in Nanotube
Uday
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Prasenjit
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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.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Nir single pixel camera. OpenStax CNX. Apr 29, 2008 Download for free at http://cnx.org/content/col10525/1.1
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