scholarly journals Defect Tolerance of Intersubband Transitions in Nonpolar GaN/(Al,Ga)N Heterostructures: A Path toward Low-Cost and Scalable Mid- to Far-Infrared Optoelectronics

2021 ◽  
Vol 16 (5) ◽  
Author(s):  
Morteza Monavarian ◽  
Jiaming Xu ◽  
Michel Khoury ◽  
Feng Wu ◽  
Philippe De Mierry ◽  
...  
Keyword(s):  
Low Cost ◽  
Far Infrared ◽  
Defect Tolerance ◽  
Intersubband Transitions ◽  
Nonpolar Gan

Low cost, high performance far infrared microbolometer

2010 ◽  
Author(s):  
Audun Roer ◽  
Adriana Lapadatu ◽  
Anders Elfving ◽  
Gjermund Kittilsland ◽  
Erling Hohler
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Far Infrared

Far‐infrared intersubband transitions in a two‐dimensional GaAs/(Al,Ga)As hole system: Direct comparison of experiment and calculation

1996 ◽  
Vol 80 (10) ◽  
pp. 6058-6060 ◽  
Author(s):  
B. E. Cole ◽  
J. M. Chamberlain ◽  
M. Henini ◽  
V. Nakov ◽  
G. Gobsch
Keyword(s):  
Far Infrared ◽  
Two Dimensional ◽  
Intersubband Transitions

Event-Locked Time-Resolved Fourier Spectroscopy

1997 ◽  
Vol 51 (8) ◽  
pp. 1106-1112 ◽  
Author(s):  
H. Weidner ◽  
R. E. Peale
Keyword(s):  
Signal To Noise Ratio ◽  
Low Cost ◽  
Michelson Interferometer ◽  
Far Infrared ◽  
Time Base ◽  
The Novel ◽  
Time Resolved ◽  
Mathematical Algorithm ◽  
Scan Time ◽  
Recorded Data

A low-cost method of adding time-resolving capability to commercial Fourier transform spectrometers with a continuously scanning Michelson interferometer has been developed. This method is specifically designed to eliminate noise and artifacts caused by mirror-speed variations in the interferometer. The method exists of two parts: (1) a novel timing scheme for synchronizing the transient events under study and the digitizing of the interferogram and (2) a mathematical algorithm for extracting the spectral information from the recorded data. The novel timing scheme is a modification of the well-known interleaved, or stroboscopic, method. It achieves the same timing accuracy, signal-to-noise ratio, and freedom from artifacts as step-scan time-resolving Fourier spectrometers by locking the sampling of the interferogram to a stable time base rather than to the occurrences of the HeNe fringes. The necessary pathlength-difference information at which samples are taken is obtained from a record of the mirror speed. The resulting interferograms with uneven pathlength-difference spacings are transformed into wavenumber space by least-squares fits of periodic functions. Spectra from the far-infrared to the upper visible at resolutions up to 0.2 cm−1 are used to demonstrate the utility of this method.

scholarly journals Infrared: A Key Technology for Security Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Carlo Corsi
Keyword(s):  
Thermal Imaging ◽  
Energy Savings ◽  
Low Cost ◽  
Far Infrared ◽  
Building Structures ◽  
Security Systems ◽  
Infrared Wavelength ◽  
Security Applications ◽  
Medical Diagnostic ◽  
Military Systems

Infrared science and technology has been, since the first applications, mainly dedicated to security and surveillance especially in military field, besides specialized techniques in thermal imaging for medical diagnostic and building structures and recently in energy savings and aerospace context. Till recently the security applications were mainly based on thermal imaging as surveillance and warning military systems. In all these applications the advent of room temperature, more reliable due to the coolers avoidance, low cost, and, overall, completely integrable with Silicon technology FPAs, especially designed and tailored for specific applications, smart sensors, has really been impacted with revolutionary and new ideas and system concepts in all the infrared fields, especially for security applications. Lastly, the advent of reliable Infrared Solid State Laser Sources, operating up to the Long Infrared Wavelength Band and the new emerging techniques in Far Infrared Submillimeter Terahertz Bands, has opened wide and new areas for developing new, advanced security systems. A review of all the items with evidence of the weak and the strong points of each item, especially considering possible future developments, will be reported and discussed.

scholarly journals Low-frequency lattice phonons in halide perovskites explain high defect tolerance toward electron-hole recombination

2020 ◽  
Vol 6 (7) ◽  
pp. eaaw7453 ◽  
Author(s):  
Weibin Chu ◽  
Qijing Zheng ◽  
Oleg V. Prezhdo ◽  
Jin Zhao ◽  
Wissam A. Saidi
Keyword(s):  
Low Cost ◽  
Low Frequency ◽  
Nonradiative Recombination ◽  
Defect Tolerance ◽  
Electron Hole ◽  
Surface Hopping ◽  
Recombination Processes ◽  
Halide Perovskites ◽  
Electron And Hole States ◽  
Hole Recombination

Low-cost solution-based synthesis of metal halide perovskites (MHPs) invariably introduces defects in the system, which could form Shockley-Read-Hall (SRH) electron-hole recombination centers detrimental to solar conversion efficiency. Here, we investigate the nonradiative recombination processes due to native point defects in methylammonium lead halide (MAPbI3) perovskites using ab initio nonadiabatic molecular dynamics within surface-hopping framework. Regardless of whether the defects introduce a shallow or deep band state, we find that charge recombination in MAPbI3 is not enhanced, contrary to predictions from SRH theory. We demonstrate that this strong tolerance against defects, and hence the breakdown of SRH, arises because the photogenerated carriers are only coupled with low-frequency phonons and electron and hole states overlap weakly. Both factors appreciably decrease the nonadiabatic coupling. We argue that the soft nature of the inorganic lattice with small bulk modulus is key for defect tolerance, and hence, the findings are general to other MHPs.

Assessment of Sampling Sufficiency for Low-Cost Satellite Missions: Application to PREFIRE

2020 ◽  
Vol 37 (12) ◽  
pp. 2283-2298
Author(s):  
Brian H. Kahn ◽  
Brian J. Drouin ◽  
Tristan S. L’Ecuyer
Keyword(s):  
Low Cost ◽  
Radiant Energy ◽  
Far Infrared ◽  
Dropping Out ◽  
Polar Regions ◽  
Full Data ◽  
Orbital Inclination ◽  
Clear Sky ◽  
Mission Duration ◽  
Glacier Ice

AbstractThe Polar Radiant Energy in the Far Infrared Experiment (PREFIRE) mission will, for the first time, systematically document the far-infrared (15–54 µm) spectral region from space. The environmental sampling characteristics of the PREFIRE CubeSats, defined in terms of surface temperature (Tsfc) and column water vapor (CWV) are evaluated for a range of possible orbit scenarios for both clear-sky and all-sky conditions over a variety of surface types (land, ocean, sea ice, snow, glacier ice) at both poles. Using NASA Aqua’s Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) retrievals to define the climatological ranges of Tsfc and CWV, the fraction of environmental regimes observed by distinct PREFIRE configurations are evaluated. The sampling rates within any single year for two-orbit CubeSat launches spanning both polar regions are ~75% for clear-sky and ~85% for all-sky compared to the AIRS/AMSU climatology. Decreasing mission duration from 12 to 3 months decreases sampling much more (10%–20%) than decreasing the swath width from 15 to 8 footprints (6%–9%). For a single CubeSat launch, a 98° orbital inclination provides slightly better sampling than either 93° or 103°. For a two-orbit CubeSat launch, a combination of 93° + 98° is somewhat preferable to 103° + 98°. Finally, a 50% data loss rate simulated by dropping out every other orbit leads to only a modest 7%–8% reduction in sampling from full data coverage. This statistical analysis demonstrates that low-cost platforms could offer similar coverage as present-day flagship missions for sampling wide-ranging Tsfc and CWV states over polar regions.

Period-doubling and Hopf bifurcations in far-infrared driven quantum well intersubband transitions

2003 ◽  
Vol 68 (3) ◽  
Author(s):  
Adriano A. Batista ◽  
Bjorn Birnir ◽  
P. I. Tamborenea ◽  
D. S. Citrin
Keyword(s):  
Quantum Well ◽  
Period Doubling ◽  
Far Infrared ◽  
Hopf Bifurcations ◽  
Intersubband Transitions

Low‐cost method for stabilization of a CO2 laser for use in far infrared laser pumping

1979 ◽  
Vol 50 (6) ◽  
pp. 791-792 ◽  
Author(s):  
Mark W. Lund ◽  
J. N. Cogan ◽  
Jeffrey A. Davis
Keyword(s):  
Co2 Laser ◽  
Low Cost ◽  
Far Infrared ◽  
Infrared Laser ◽  
Far Infrared Laser ◽  
Laser Pumping

scholarly journals AutoTriage - An Open Source Edge Computing Raspberry Pi-based Clinical Screening System

2020 ◽  
Author(s):  
Chaitra Hegde ◽  
Zifan Jiang ◽  
Pradyumna Byappanahalli Suresha ◽  
Jacob Zelko ◽  
Salman Seyedi ◽  
...  
Keyword(s):  
Open Source ◽  
Low Cost ◽  
Characteristic Curve ◽  
Rapid Assessment ◽  
Infrared Camera ◽  
Visible Spectrum ◽  
Wait Time ◽  
Far Infrared ◽  
Raspberry Pi ◽  
Body Parts

AbstractWith the recent COVID-19 pandemic, healthcare systems all over the world are struggling to manage the massive increase in emergency department (ED) visits. This has put an enormous demand on medical professionals. Increased wait times in the ED increases the risk of infection transmission. In this work we present an open-source, low cost, off-body system to assist in the automatic triage of patients in the ED based on widely available hardware. The system initially focuses on two symptoms of the infection fever and cyanosis. The use of visible and far-infrared cameras allows for rapid assessment at a 1m distance, thus reducing the load on medical staff and lowering the risk of spreading the infection within hospitals. Its utility can be extended to a general clinical setting in non-emergency times as well to reduce wait time, channel the time and effort of healthcare professionals to more critical tasks and also prioritize severe cases.Our system consists of a Raspberry Pi 4, a Google Coral USB accelerator, a Raspberry Pi Camera v2 and a FLIR Lepton 3.5 Radiometry Long-Wave Infrared Camera with an associated IO module. Algorithms running in real-time detect the presence and body parts of individual(s) in view, and segments out the forehead and lip regions using PoseNet. The temperature of the forehead-eye area is estimated from the infrared camera image and cyanosis is assessed from the image of the lips in the visible spectrum. In our preliminary experiments, an accuracy of 97% was achieved for detecting fever and 77% for the detection of cyanosis, with a sensitivity of 91% and area under the receiver operating characteristic curve of 0.91. Heart rate and respiratory effort are also estimated from the visible camera.Although preliminary results are promising, we note that the entire system needs to be optimized before use and assessed for efficacy. The use of low-cost instrumentation will not produce temperature readings and identification of cyanosis that is acceptable in many situations. For this reason, we are releasing the full code stack and system design to allow others to rapidly iterate and improve the system. This may be of particular benefit in low-resource settings, and low-to-middle income countries in particular, which are just beginning to be affected by COVID-19.

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