Uncloaking Diffusive-Light Invisibility Cloaks by Speckle Analysis
Within the range of validity of the stationary diffusion equation, an ideal diffusive-light invisibility cloak can make an arbitrary macroscopic object hidden inside of the cloak indistinguishable from the surroundings for all colors, polarizations, and directions of incident visible light. However, the diffusion equation for light is an approximation which becomes exact only in the limit of small coherence length. Thus, one expects that the cloak can be revealed by illumination with coherent light. The experiments presented here show that the cloaks are robust in the limit of large coherence length but can be revealed by analysis of the speckle patterns under illumination with partially coherent light. Experiments on cylindrical core-shell cloaks and corresponding theory are in good agreement.
A. Niemeyer et al., "Uncloaking Diffusive-Light Invisibility Cloaks by Speckle Analysis," Optics Letters, vol. 42, no. 10, pp. 1998-2001, Optical Society of America (OSA), May 2017.
The definitive version is available at https://doi.org/10.1364/OL.42.001998
Keywords and Phrases
Coherent light; Light; Partial differential equations; Speckle, Coherence lengths; Cylindrical cores; Diffusion equations; Macroscopic objects; Partially coherent light; Speckle patterns; Stationary diffusion; Visible light, Invisibility cloaks
International Standard Serial Number (ISSN)
Article - Journal
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01 May 2017