By synthesizing large effective apertures through the translation of a smaller imaging sensor and the subsequent proper phasing and correlation of detected signals in postprocessing, holographic aperture ladar (HAL) systems seek to increase the resolution of remotely imaged targets. The stripmap HAL process was demonstrated in the laboratory, for the first time to our knowledge. Our results show that the stripmap HAL transformation can precisely account for off-axis transmitter induced phase migrations. This in turn allows multiple pupil plane field segments, sequentially collected across a synthetic aperture, to be coherently mosaiced together. As a direct consequence, we have been able to confirm the capability of the HAL method to potentially provide substantial increases in longitudinal cross-range resolution. The measurement and sampling of complex pupil plane field segments, as well as target related issues arising from short laboratory ranges, have also been addressed.
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http://dx.doi.org/10.1364/AO.49.002262 | DOI Listing |
High-resolution X-ray imaging of noncrystalline objects is often achieved through the approach of scanning coherent diffractive imaging known as ptychography. The imaging resolution is usually limited by the scattering properties of the sample, where weak diffraction signals at the highest scattering angles compete with parasitic scattering. Here, we demonstrate that X-ray multilayer Laue lenses with a high numerical aperture (NA) can be used to create a strong reference beam that holographically boosts weak scattering from the sample over a large range of scattering angles, enabling high-resolution imaging that is tolerant of such background.
View Article and Find Full Text PDFInspired by the wavefront masking of the scattering medium, we proposed a multiplexed coded aperture holographic encryption method. The incoherent multiplexed phase mask encryption experiments involved in the method are realized for what we believe to be the first time. From the holograms, we extracted three images using the frequency-selective phase iterative coding algorithm we purposely put forward.
View Article and Find Full Text PDFIn this work, an experimental analysis of hololens imaging configuration consisting of four holographic lenses has been carried out to realize Duffy's double aperture speckle interferometer. It is demonstrated that using holographic lenses recorded for typical -number in the four-hololens imaging system, the sensitivity of measurement is not limited due to the -number of the lens. However, the sensitivity can be significantly enhanced by increasing the angle between the plane and spherical waves while recording the holographic lenses.
View Article and Find Full Text PDFNano Lett
June 2024
Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710129, China.
Orbital angular momentum (OAM) multiplexed holograms have attracted a great deal of attention recently due to their physically unbounded set of orthogonal helical modes. However, preserving the OAM property in each pixel hinders fine sampling of the target image in principle and requires a fundamental filtering aperture array in the detector plane. Here, we demonstrate the concept of metasurface-based vectorial holography with cylindrical vector beams (CVBs), whose unlimited polarization orders and unique polarization distributions can be used to boost information storage capacity.
View Article and Find Full Text PDFWe present a noninvasive method for quantitative phase imaging through dynamically scattering media. A complex amplitude object, illuminated with coherent light, is captured through a dynamically scattering medium and a variable coded aperture, without the need for interferometric measurements or imaging optics. The complex amplitude of the object is computationally retrieved from intensity images that use multiple coded aperture patterns, employing a stochastic gradient descent algorithm.
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