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We demonstrate high numerical aperture (NA=0.8) transmissive metasurface-based lenses with efficiencies as high as 86% in the visible spectrum. Meta-lenses allow diffraction-limited focusing at red (λ=660 nm), green (λ=532 nm), and blue (λ=405 nm) wavelengths. They can resolve nanoscale features with sub-wavelength gaps.
We describe a system for content-based retrieval from large surveillance video archives, using behavior, action and appearance of objects. Objects are detected, tracked, and classified into broad categories. Their behavior and appearance are characterized by action detectors and descriptors, which are indexed in an archive. Queries can be posed as video exemplars, and the results can be refined through...
It is difficult to measure the response of a structure to an explosive blast because of the high speed and transient nature of the deformation and also the severity of shock effects. Measurement approaches using strain gages and accelerometers provide point-wise information only and may be adversely influenced by shock-related noise. Further, attached sensors of even small mass can separate from the...
Reflecting objects such as tea pots and glasses, but also diffusely reflecting objects such as a user's shirt, can be used to spy on confidential data displayed on a monitor. First, we show how reflections in the user's eye can be exploited for spying on confidential data. Second, we investigate to what extent monitor images can be reconstructed from the diffuse reflections on a wall or the user's...
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