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We present a method to measure quadratic Terahertz optical nonlinearities in Terahertz time-domain spectroscopy. We use a rotating linear polarizer (a polarizing chopper) to modulate the amplitude of the incident THz pulse train. We use a…

Applied Physics · Physics 2018-10-16 Shuai Lin , Shukai Yu , Diyar Talbayev

We present a novel convex relaxation and a corresponding inference algorithm for the non-binary discrete tomography problem, that is, reconstructing discrete-valued images from few linear measurements. In contrast to state of the art…

Optimization and Control · Mathematics 2018-12-27 Jan Kuske , Paul Swoboda , Stefania Petra

Infrared thermography (IRT) and photothermal coherence tomography (PCT) exhibit potential in non-destructive testing and biomedical fields. However, the inevitable heat diffusion significantly affects the sensitivity and resolution of IRT…

We give uniqueness theorem and reconstruction algorithm for the nonlinearized problem of finding the dielectric anisotropy f of the medium from non-overdetermined polarization tomography data. We assume that the medium has uniform…

Mathematical Physics · Physics 2015-05-13 Roman Novikov

Image dehazing, a pivotal task in low-level vision, aims to restore the visibility and detail from hazy images. Many deep learning methods with powerful representation learning capability demonstrate advanced performance on non-homogeneous…

Computer Vision and Pattern Recognition · Computer Science 2024-07-09 Wei Dong , Han Zhou , Ruiyi Wang , Xiaohong Liu , Guangtao Zhai , Jun Chen

TeraHertz (THz) communications are envisioned as a promising technology, owing to its unprecedented multi-GHz bandwidth. One fundamental challenge when moving to new spectrum is to understand the science of radio propagation and develop an…

Information Theory · Computer Science 2021-02-01 Yi Chen , Yuanbo Li , Chong Han , Ziming Yu , Guangjian Wang

Rydberg atom-based sensors have emerged as highly sensitive tools for terahertz (THz) metrology, yet most current imaging techniques discard crucial phase information. In this Letter, we present a coherent THz-to-optical conversion scheme…

The problem of image reconstruction in thermoacoustic tomography requires inversion of a generalized Radon transform, which integrates the unknown function over circles in 2D or spheres in 3D. The paper investigates implementation of the…

Numerical Analysis · Mathematics 2007-05-23 Gaik Ambartsoumian , Sarah K. Patch

THz spectroscopy is an emerging tool for detection of microorganisms and harmful compounds in the food industry, the study of proteins in biomedicine and the development of electron-beam X-ray sources for molecular imaging and lithography.…

Coherent continuous wave (CW) terahertz spectroscopy is an extremely valuable technique that allows for the interrogation of systems that exhibit narrow resonances in the terahertz (THz) frequency range, such as high-quality (high-Q) THz…

Optics · Physics 2019-05-01 Dominik Walter Vogt , Miro Erkintalo , Rainer Leonhardt

Time-resolved terahertz time-domain spectroscopy (THz-TDS) is an ideal tool for probing photoinduced nonequilibrium metallic and superconducting states. Here, we focus on the interpretation of the two-dimensional response function…

Superconductivity · Physics 2015-10-14 J. Orenstein , J. S. Dodge

Radon Transformation is generally used to construct optical image (like CT image) from the projection data in biomedical imaging. In this paper, the concept of Radon Transformation is implemented to reconstruct Electrical Impedance…

Computer Vision and Pattern Recognition · Computer Science 2012-11-07 Md. Ali Hossain , Ahsan-Ul-Ambia , Md. Aktaruzzaman , Md. Ahaduzzaman Khan

Microorganisms are ubiquitous in nature, and microbial activities are closely intertwined with the entire life cycle system and human life. Developing novel technologies for the detection, characterization and manipulation of microorganisms…

Optics · Physics 2025-10-17 Ding Cao , Guangyou Fang , Xuequan Chen

Most quantum tomographic methods can only be used for one-dimensional problems. We show how to infer the quantum state of a non-relativistic N-dimensional harmonic oscillator system by simple inverse Radon transforms. The procedure is…

Quantum Physics · Physics 2009-11-11 Anders S. Mouritzen , Klaus Molmer

In this contribution, we explore the imaging limits of terahertz single-pixel cameras and present a way to improve the achievable signal-to-noise ratio and spatial resolution using a technique called dithering masks. The proposed procedure…

Instrumentation and Detectors · Physics 2017-11-10 Sven Augustin , Tom Szollmann , Peter Jung , Heinz-Wilhelm Huebers

Terahertz (THz) emissions from fast electron and ion currents driven in relativistic, femtosecond laser-foil interactions are examined theoretically. We first consider the radiation from the energetic electrons exiting the backside of the…

Plasma Physics · Physics 2023-12-15 E. Denoual , L. Bergé , X. Davoine , L. Gremillet

Tomographic reconstruction of reionization is a long-sought goal. It would move the field beyond global summary statistics, such as the volume-averaged ionised fraction, to direct, field-level constraints on the ionization topology. With…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-26 Soumak Maitra , Girish Kulkarni , Vipul Arora , Matteo Viel , Shikhar Asthana , James S. Bolton , Martin G. Haehnelt , Laura Keating

The Rytov approximation has been commonly used to obtain reconstructed images for optical tomography. However, the method requires linearization of the nonlinear inverse problem. Here, we demonstrate nonlinear Rytov approximations by…

Medical Physics · Physics 2024-11-26 Chi Zhang , Manabu Machida

Image reconstruction in X ray tomography consists in determining an object from its projections. In many applications such as non destructive testing, we look for an image who has a constant value inside a region (default) and another…

Data Analysis, Statistics and Probability · Physics 2007-05-23 A. Mohammad-Djafari

We demonstrate structured illumination super-resolution imaging in the Terahertz (THz) frequency band using the Virtually Structured Detection (VSD) method. Leveraging our previously reported high-speed, high-sensitivity atomic-based THz…