Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2004-11-24
2008-10-07
Epps, Georgia Y. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S208100
Reexamination Certificate
active
07432485
ABSTRACT:
An optical arrangement of at least a coherent light source (1), a strongly scattering object (5) (the PUF), and a pixe-lated photo-detector (6), wherein the pixels are comparable in size with the bright and dark patches of the speckle pattern produced by coherent radiation traversing the scattering object (5). Quantitively, the pixel size should be roughly λ/NA, where λ is the wave-length, and (i) NA=a/z for free-space geometry, with a being the beam radius and z being the distance between the exit surface of the PUF (5) and the pixelated detector (6), or (ii) NA is the numerical aperture of a lens (7) in an imaging geometry. In a preferred embodiment of the invention, there are tentative requirements that the pixels should be at least smaller than ηmaxλNA and preferably larger than ηmaxλ/NA, where (in an exemplary embodiment) ηmax=5 and ηmin=0.05, say. It will be understood by a person skilled in the art that the present invention is concerned with the optical arrangement of the PUF (5) and the photo-detector (6), rather than the photo -detector (6) per se.
REFERENCES:
patent: 2003/0142379 (2003-07-01), Takemori et al.
patent: 2004/0118919 (2004-06-01), Breytman et al.
Creath, Katherine “Phase-Shifting Speckle Interferometry”, Applied Optics, vol. 24, No. 18, Sep. 15, 1985, pp. 3053-3058, XP002316841.
Ravikanth Pappu, “Physical One Way Functions”, Science, vol. 297, Sep. 20, 2002, pp. 2026-2030, XP002316842.
B.L.P. Gassend, “Physical Random Functions; Thesis”, Massachusetts Ins. of Technology, Feb. 2003, XP002316843.
Akkermans Antonius Hermanus Maria
Ophey Willem Gerard
Skoric Boris
Stallinga Sjoerd
Tuyls Pim Theo
Belk Michael E.
Epps Georgia Y.
Koninklijke Philips Electronics , N.V.
Williams Don
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