1,721,078 research outputs found
Lensless digital holographic microscope with light-emitting diode illumination
No full textWe demonstrate the operation of a digital in-line microscope with LED illumination. We show with a practical example that, for typical setups, the limited temporal coherence and the spatial incoherence of the source do not affect the resolving power of the system. On the contrary, important advantages are obtained in terms of signal-to-noise ratio and alignment simplification
REFERENCE LEAKAGE DEVICE FOR LEAK CALIBRATION
No full textReference leakage device (1) for use in leakage detection of gas, comprises a membrane (5) adapted to be interposed between two environments having respective pressures pu and pa, where (I). The membrane has an orifice (6) adapted to determine a controlled gas flow depending on the pressure pu. The orifice has a preset diameter D and length L such that (II). The diameter D and the length L are further dimensioned in such a manner that the equivalent diameter De of the orifice is De≦100 nm, where De is defined by the relation De=D.a1/2 wherein a is the transmission probability of the orifice, function of the L/D ratio. The orifice is adapted to operate in molecular flow regime in an entire range of pυ values comprising the value of atmospheric pressure
Infrared lensless holographic microscope with a vidicon camera for inspection of metallic evaporations on silicon wafers
No full textThe lensless digital in-line microscope is proposed as a simple tool for post-production inspection of metallic film
patterns on silicon wafers. Transmission holographic imaging is achieved by using a superluminescent diode emitting
in the near infrared coupled into a single-mode high numerical aperture optical fiber and an infrared vidicon camera.
Images of 300 nm thick vapor-deposited aluminum bolometers are presented
Label-free, atomic force microscopy-based mapping of DNA intrinsic curvature for the nanoscale comparative analysis of bent duplexes
No full textWe propose a method for the characterization of the local intrinsic curvature of adsorbed DNA molecules. It relies on a novel statistical chain descriptor, namely the ensemble averaged product of curvatures for two nanosized segments, symmetrically placed on the contour of atomic force microscopy imaged chains. We demonstrate by theoretical arguments and experimental investigation of representative samples that the fine mapping of the average product along the molecular backbone generates a characteristic pattern of variation that effectively highlights all pairs of DNA tracts with large intrinsic curvature. The centrosymmetric character of the chain descriptor enables targetting strands with unknown orientation. This overcomes a remarkable limitation of the current experimental strategies that estimate curvature maps solely from the trajectories of end-labeled molecules or palindromes. As a consequence our approach paves the way for a reliable, unbiased, label-free comparative analysis of bent duplexes, aimed to detect local conformational changes of physical or biological relevance in large sample numbers. Notably, such an assay is virtually inaccessible to the automated intrinsic curvature computation algorithms proposed so far. We foresee several challenging applications, including the validation of DNA adsorption and bending models by experiments and the discrimination of specimens for genetic screening purposes
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