scholarly journals Three-dimensional radiometric aperture synthesis microscopy for security screening

2014 ◽  
Author(s):  
Neil A. Salmon ◽  
Nick Bowring
Keyword(s):  
Three Dimensional ◽  
Aperture Synthesis ◽  
Security Screening

scholarly journals Magnetic Field Structure of Star Forming Regions: VLBI Spectral Line Results

1984 ◽  
Vol 110 ◽  
pp. 333-334
Author(s):  
J.A. Garcia-Barreto ◽  
B. F. Burke ◽  
M. J. Reid ◽  
J. M. Moran ◽  
A. D. Haschick
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Aperture Synthesis ◽  
Stokes Parameters ◽  
Hii Region ◽  
Star Forming ◽  
Star Forming Regions ◽  
Vlbi Observations ◽  
The Magnetic Field ◽  
Synthesis Experiment

Magnetic fields play a major role in the general dynamics of astronomical phenomena and particularly in the process of star formation. The magnetic field strength in galactic molecular clouds is of the order of few tens of μG. On a smaller scale, OH masers exhibit fields of the order of mG and these can probably be taken as representative of the magnetic field in the dense regions surrounding protostars. The OH molecule has been shown to emit highly circular and linearly polarized radiation. That it was indeed the action of the magnetic field that would give rise to the highly polarized spectrum of OH has been shown by the VLBI observations of Zeeman pairs of the 1720 and 6035 MHz by Lo et. al. and Moran et. al. VLBI observations of W3 (OH) revealed that the OH emission was coming from numerous discrete locations and that all spots fell within the continuum contours of the compact HII region. The most detailed VLBI aperture synthesis experiment of the 1665 MHz emission from W3 (OH) was carried out by Reid et. al. who found several Zeeman pairs and a characteristic maser clump size of 30 mas. In this work, we report the results of a 5 station VLBI aperture synthesis experiment of the 1665 MHz OH emission from W3 (OH) with full polarization information. We produced VLBI synthesis maps of all Stokes parameters of 16 spectral features that showed elliptical polarization. The magnitude and direction of the magnetic field have been obtained by the detection of 7 Zeeman pairs. The three dimensional orientation of the magnetic field can be obtained, following the theoretical arguments of Goldreich et. al., from the observation of π and σ components.

scholarly journals Three dimensional digital holographic aperture synthesis

2015 ◽  
Vol 23 (18) ◽  
pp. 23811 ◽  
Author(s):  
Stephen Crouch ◽  
Brant M. Kaylor ◽  
Zeb W. Barber ◽  
Randy R. Reibel
Keyword(s):  
Three Dimensional ◽  
Aperture Synthesis

Three-dimensional digital holographic aperture synthesis for rapid and highly-accurate large-volume metrology

2015 ◽  
Author(s):  
Stephen Crouch ◽  
Brant M. Kaylor ◽  
Zeb W. Barber ◽  
Randy R. Reibel
Keyword(s):  
Large Volume ◽  
Three Dimensional ◽  
Aperture Synthesis

scholarly journals Three-Dimensional Holographic Imaging Using Single Frequency Microwave Data

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Reza K. Amineh ◽  
Maryam Ravan ◽  
Raveena Sharma ◽  
Smit Baua
Keyword(s):  
3D Imaging ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Single Frequency ◽  
Low Frequencies ◽  
Reconstruction Process ◽  
Security Screening ◽  
Holographic Imaging ◽  
Wave Imaging ◽  
The Media

Three-dimensional (3D) microwave and millimeter wave imaging techniques based on the holographic principles have been successfully employed in several applications such as security screening, body shape measurement for the apparel industry, underground imaging, and wall imaging. The previously proposed 3D holographic imaging techniques require the acquisition of wideband data over rectangular or cylindrical apertures. Requirement for wideband data imposes limitations on the hardware (in particular at very high or very low frequencies). It may also lead to errors in the produced images if the media is dispersive (e.g., in biomedical imaging) and not modeled properly in the image reconstruction process. To address these limitations, here, we propose a technique to perform 3D imaging with single frequency data. Instead of collecting data at multiple frequencies, we acquire the backscattered fields with an array of resonant antennas. We demonstrate the possibility of 3D imaging with the proposed setup and perform a comprehensive study of the capabilities and limitations of the technique via simulations. To perform a realistic study, the simulation data is contaminated by noise.

scholarly journals Three-dimensional cross-nanowire networks recover full terahertz state

Science ◽  
2020 ◽  
Vol 368 (6490) ◽  
pp. 510-513 ◽  
Author(s):  
Kun Peng ◽  
Dimitars Jevtics ◽  
Fanlu Zhang ◽  
Sabrina Sterzl ◽  
Djamshid A. Damry ◽  
...  
Keyword(s):  
Polarization State ◽  
Three Dimensional ◽  
Wide Band ◽  
Field Vector ◽  
Infrared Light ◽  
Electromagnetic Spectrum ◽  
Polarization Component ◽  
Security Screening ◽  
Orthogonal Components ◽  
Nanowire Networks

Terahertz radiation encompasses a wide band of the electromagnetic spectrum, spanning from microwaves to infrared light, and is a particularly powerful tool for both fundamental scientific research and applications such as security screening, communications, quality control, and medical imaging. Considerable information can be conveyed by the full polarization state of terahertz light, yet to date, most time-domain terahertz detectors are sensitive to just one polarization component. Here we demonstrate a nanotechnology-based semiconductor detector using cross-nanowire networks that records the full polarization state of terahertz pulses. The monolithic device allows simultaneous measurements of the orthogonal components of the terahertz electric field vector without cross-talk. Furthermore, we demonstrate the capabilities of the detector for the study of metamaterials.

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