Random scattering of light by a turbid layer prevents conventional imaging of objects hidden behind it. Angular correlations in the scattered light, created by the so-called optical memory effect, have been shown to enable computational image retrieval of hidden sources. However, basic memory-effect imaging contains no spatial (x) information, as only angular (k-space) measurements are made. Here, we use windowed Fourier transforms to record scattered-light images in the full {x,k} phase space. The result is the ability to discriminate size and depth of individual sources that are hidden behind a thin scattering layer.
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http://dx.doi.org/10.1364/OE.22.031426 | DOI Listing |
Ghost imaging enables the imaging of an object using intensity correlations between a single-pixel detector placed behind the object and a camera that records the light that did not interact with the object. The object and the camera are often placed at conjugate planes to ensure correlated illumination patterns. Here, we show how the combined effect of optical reciprocity and the memory effect in a random medium gives rise to correlations between two beams that traverse the random medium in opposite directions.
View Article and Find Full Text PDFThe use of wavefront shaping has found extensive application to develop ultra-thin endoscopic techniques based on multimode optical fibers (MMF), leveraging on the ability to control modal interference at the fiber's distal end. Although several techniques have been developed to achieve MMF-based laser-scanning imaging, the use of short laser pulses is still a challenging application. This is due to the intrinsic delay and temporal broadening introduced by the fiber itself, which requires additional compensation optics on the reference beam during the calibration procedure.
View Article and Find Full Text PDFSpeckle correlation imaging (SCI) recovers the angular size of a 2D object hidden behind a scatterer, but it fails to recover its depth. Here, we extend SCI to obtain object depth by capturing speckled images at two detector distances and exploiting the scaling properties of the axial memory effect. This noninvasive method does not require access to the object side of the scatterer, e.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
October 2024
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853.
Memory effect refers to the phenomenon where past events influence a system's current and future states or behaviors. In biology, memory effects often arise from intra- or intermolecular interactions, leading to temporally correlated behaviors. Single-molecule studies have shown that enzymes and DNA-binding proteins can exhibit time-correlated behaviors of their activity.
View Article and Find Full Text PDFMaterials (Basel)
September 2024
Dongnam Regional Division, Korea Institute of Industrial Technology, Yangsan 50623, Republic of Korea.
In this study, microstructure, mechanical, and shape memory properties of the welded Fe-based shape memory alloy (Fe-SMA) plates with a nominal composition of Fe-17Mn-5Si-10Cr-4Ni-(V, C) (wt.%) by gas tungsten arc welding were investigated. The optimal heat input to ensure full penetration of the Fe-SMA plate with a thickness of 2 mm was found to be 0.
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