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SUMMARY:Magic mirrors and magic windows - Michael Berry (University of Bri
 stol)
DTSTART:20171128T093000Z
DTEND:20171128T101000Z
UID:TALK96067@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Ancient oriental mirrors possess a property that seemed magica
 l and was probably unintended by those who made them: the pattern embossed
  on the back of such a mirror appears in light reflected onto a screen fro
 m its apparently featureless front surface. In reality\, the embossed patt
 ern is reproduced on the front\, in low relief invisible to direct observa
 tion\, and analysis shows that the projected image results from pre-focal 
 ray deviation. In this interesting regime of geometrical optics\, the imag
 e intensity is given simply by the Laplacian of the height function of the
  relief. Observation confirms this &lsquo\;Laplacian image&rsquo\; interpr
 etation\, and indicates that steps on the reflecting surface are about 400
  nm high\, explaining their invisibility. Current research aims to create 
 the transparent analogue of the magic mirror: &lsquo\;magic windows&rsquo\
 ;\, in which glass sheets\, flat to unaided vision but with gentle surface
  relief\, concentrate light onto a screen with intens ity reproducing any 
 desired image. Laplacian image theory implies that the desired surface rel
 ief is obtained by solving Poisson&rsquo\;s equation.<br><br>Related Links
 <ul><li><a target="_blank" rel="nofollow">https://michaelberryphysics.word
 press.com</a></li></ul>
LOCATION:Seminar Room 1\, Newton Institute
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