| 摘要 |
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 lambda/NA, where lambda 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 eta<SUB>max</SUB>lambdaNA and preferably larger than eta<SUB>max</SUB>lambda/NA, where (in an exemplary embodiment) eta<SUB>max</SUB>=5 and eta<SUB>min</SUB>=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.
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