scholarly journals A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Yoichiro Hanaoka ◽  
Yukio Katsukawa ◽  
Satoshi Morita ◽  
Yukiko Kamata ◽  
Noriyoshi Ishizuka
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
High Performance ◽  
Near Infrared ◽  
Infrared Camera ◽  
Solar Magnetic Fields ◽  
Solar Filaments ◽  
Infrared Wavelengths ◽  
Solar Polarimetry ◽  
The Magnetic Field

AbstractPolarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar filaments, which occasionally erupt and develop into interplanetary flux ropes, is of particular interest. To measure the magnetic field in filaments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has $$2048~\times 2048$$ 2048 × 2048 pixels, focusing on the wavelengths in the range of $$1.0\;{-}\;1.6\;~\mu {\text{m}} $$ 1.0 - 1.6 μ m . We solved the problem of the difficult operation of the H2RGs under “fast readout mode” synchronizing with high-speed polarization modulation by introducing a “MACIE” (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific. This enables polarization measurements with high frame-rates, such as 29–117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.

scholarly journals A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry

2020 ◽  
Author(s):  
Yoichiro Hanaoka ◽  
Yukio Katsukawa ◽  
Satoshi Morita ◽  
Yukiko Kamata ◽  
Noriyoshi Ishizuka
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
High Performance ◽  
Near Infrared ◽  
Infrared Camera ◽  
Polarization Modulation ◽  
Solar Magnetic Fields ◽  
Infrared Wavelengths ◽  
Solar Polarimetry ◽  
The Magnetic Field

Abstract Polarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar laments, which occasionally erupt and develop into interplanetary flux ropes, is of particular interest. To measure the magnetic field in laments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has 2048 x 2048 pixels, focusing on the wavelengths in the range of 1.0{1.6 um. We solved the problem of the difficult operation of the H2RGs under "fast readout mode" synchronizing with high-speed polarization modulation by introducing a "MACIE" (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific This enables polarization measurements with high frame-rates, such as 29{117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.

scholarly journals A HAWAII-2RG Infrared Camera Operated Under Fast Readout Mode for Solar Polarimetry

2020 ◽  
Author(s):  
Yoichiro Hanaoka ◽  
Yukio Katsukawa ◽  
Satoshi Morita ◽  
Yukiko Kamata ◽  
Noriyoshi Ishizuka
Keyword(s):  
Space Weather ◽  
High Speed ◽  
High Performance ◽  
Near Infrared ◽  
Infrared Camera ◽  
Polarization Modulation ◽  
The Sun ◽  
Interface Card ◽  
Infrared Wavelengths ◽  
Solar Polarimetry

Abstract Polarimetry is a crucial method to investigate solar magnetic elds. From the viewpoint of space weather, the magnetic eld in solar laments, which occasionally erupt and develop into interplanetary ux ropes, is of particular interest. To measure the magnetic eld in laments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has 2048 2048 pixels, focusing on the wavelengths in the range of 1.0{1.6 m. We solved the problem of the difficult operation of the H2RGs under \fast readout mode" synchronizing with high-speed polarization modulation by introducing a \MACIE" (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientic. This enables polarization measurements with high frame-rates, such as 29{117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and conrmed the high polarimetric performance of the camera.

Magnetic Field Spectroheliograms from the San Fernando Observatory

1971 ◽  
Vol 43 ◽  
pp. 329-339 ◽  
Author(s):  
Dale Vrabec
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spiral Structure ◽  
Longitudinal Component ◽  
Solar Telescope ◽  
Solar Magnetic Fields ◽  
San Fernando ◽  
Field Lines ◽  
The Magnetic Field ◽  
Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

Experimental investigation and optimization on field shaper structure parameters in magnetic pulse welding

2021 ◽  
pp. 095440542110148
Author(s):  
Yingzi Chen ◽  
Zhiyuan Yang ◽  
Wenxiong Peng ◽  
Huaiqing Zhang
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Light Metal ◽  
Magnetic Pulse ◽  
Cross Sectional ◽  
Magnetic Pulse Welding ◽  
Pulse Welding ◽  
Sectional Shape ◽  
Welding System ◽  
The Magnetic Field

Magnetic pulse welding is a high-speed welding technology, which is suitable for welding light metal materials. In the magnetic pulse welding system, the field shaper can increase the service life of the coil and contribute to concentrating the magnetic field in the welding area. Therefore, optimizing the structure of the field shaper can effectively improve the efficiency of the system. This paper analyzed the influence of cross-sectional shape and inner angle of the field shaper on the ability of concentrating magnetic field via COMSOL software. The structural strength of various field shapers was also analyzed in ABAQUS. Simulation results show that the inner edge of the field shaper directly affects the deformation and welding effect of the tube. So, a new shape of field shaper was proposed and the experimental results prove that the new field shaper has better performance than the conventional field shaper.

Spectral characteristics of leafy spurge (Euphorbia esula) leaves and flower bracts

Weed Science ◽  
2004 ◽  
Vol 52 (4) ◽  
pp. 492-497 ◽  
Author(s):  
E. Raymond Hunt ◽  
James E. McMurtrey ◽  
Amy E. Parker Williams ◽  
Lawrence A. Corp
Keyword(s):  
Remote Sensing ◽  
High Performance ◽  
Near Infrared ◽  
Spectral Characteristics ◽  
Leafy Spurge ◽  
Hyperspectral Remote Sensing ◽  
Total Carotenoids ◽  
Physiological Basis ◽  
Infrared Wavelengths ◽  
Pigment Concentrations

Leafy spurge can be detected during flowering with either aerial photography or hyperspectral remote sensing because of the distinctive yellow-green color of the flower bracts. The spectral characteristics of flower bracts and leaves were compared with pigment concentrations to determine the physiological basis of the remote sensing signature. Compared with leaves of leafy spurge, flower bracts had lower reflectance at blue wavelengths (400 to 500 nm), greater reflectance at green, yellow, and orange wavelengths (525 to 650 nm), and approximately equal reflectances at 680 nm (red) and at near-infrared wavelengths (725 to 850 nm). Pigments from leaves and flower bracts were extracted in dimethyl sulfoxide, and the pigment concentrations were determined spectrophotometrically. Carotenoid pigments were identified using high-performance liquid chromatography. Flower bracts had 84% less chlorophylla, 82% less chlorophyllb, and 44% less total carotenoids than leaves, thus absorptance by the flower bracts should be less and the reflectance should be greater at blue and red wavelengths. The carotenoid to chlorophyll ratio of the flower bracts was approximately 1:1, explaining the hue of the flower bracts but not the value of reflectance. The primary carotenoids were lutein, β-carotene, and β-cryptoxanthin in a 3.7:1.5:1 ratio for flower bracts and in a 4.8:1.3:1 ratio for leaves, respectively. There was 10.2 μg g−1fresh weight of colorless phytofluene present in the flower bracts and none in the leaves. The fluorescence spectrum indicated high blue, red, and far-red emission for leaves compared with flower bracts. Fluorescent emissions from leaves may contribute to the higher apparent leaf reflectance in the blue and red wavelength regions. The spectral characteristics of leafy spurge are important for constructing a well-documented spectral library that could be used with hyperspectral remote sensing.

scholarly journals Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 428
Author(s):  
Reza Masoudian Saadabad ◽  
Christian Pauly ◽  
Norbert Herschbach ◽  
Dragomir N. Neshev ◽  
Haroldo T. Hattori ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
High Speed ◽  
Near Infrared ◽  
Infrared Detector ◽  
High Quantum Efficiency ◽  
Fast Detection ◽  
High Quantum ◽  
Resonant Modes ◽  
Infrared Wavelengths ◽  
Dielectric Metasurface

Fast detection of near-infrared (NIR) photons with high responsivity remains a challenge for photodetectors. Germanium (Ge) photodetectors are widely used for near-infrared wavelengths but suffer from a trade-off between the speed of photodetection and quantum efficiency (or responsivity). To realize a high-speed detector with high quantum efficiency, a small-sized photodetector efficiently absorbing light is required. In this paper, we suggest a realization of a dielectric metasurface made of an array of subwavelength germanium PIN photodetectors. Due to the subwavelength size of each pixel, a high-speed photodetector with a bandwidth of 65 GHz has been achieved. At the same time, high quantum efficiency for near-infrared illumination can be obtained by the engineering of optical resonant modes to localize optical energy inside the intrinsic Ge disks. Furthermore, small junction capacitance and the possibility of zero/low bias operation have been shown. Our results show that all-dielectric metasurfaces can improve the performance of photodetectors.

scholarly journals Simulation study of the plasma-brake effect

2014 ◽  
Vol 32 (10) ◽  
pp. 1207-1216 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ionospheric Plasma ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Breaking Force ◽  
Field Orientation ◽  
Particle In Cell ◽  
Leo Satellite ◽  
The Magnetic Field

Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

scholarly journals Heterostructured silicon-germanium-silicon p-i-n avalanche photodetectors for chip-integrated optoelectronics -INVITED

2021 ◽  
Vol 255 ◽  
pp. 01002
Author(s):  
Daniel Benedikovic ◽  
Leopold Virot ◽  
Guy Aubin ◽  
Jean-Michel Hartmann ◽  
Farah Amar ◽  
...  
Keyword(s):  
Health Monitoring ◽  
Optical Communications ◽  
Silicon Germanium ◽  
High Speed ◽  
Near Infrared ◽  
Building Blocks ◽  
Electrical Signal ◽  
Avalanche Photodetectors ◽  
Infrared Wavelengths ◽  
Germanium Silicon

Optical photodetectors are at the forefront of photonic research since the rise of integrated optics. Photodetectors are fundamental building blocks for chip-scale optoelectronics, enabling conversion of light into an electrical signal. Such devices play a key role in many surging applications from communication and computation to sensing, biomedicine and health monitoring, to name a few. However, chip integration of optical photodetectors with improved performances is an on-going challenge for mainstream optical communications at near-infrared wavelengths. Here, we present recent advances in heterostructured silicon-germanium-silicon p-i-n photodetectors, enabling high-speed detection on a foundry-compatible monolithic platform.

scholarly journals Near Infrared Polarimetry of Dark Clouds and Star Forming Regions - Two Micron Polarization Survey of T Tauri Stars

1990 ◽  
Vol 140 ◽  
pp. 327-328
Author(s):  
M. Tamura ◽  
S. Sato
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Near Infrared ◽  
Background Field ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions ◽  
Stellar Sources ◽  
Geometrical Relationship ◽  
The Magnetic Field

Infrared polarimetry is one of the most useful methods to delineate the magnetic field structure in dark clouds and star-forming regions, where the intracloud extinction is so large that optical polarimetry is inaccessible. We have been conducting a near-infrared polarization survey of background field stars and embedded sources toward nearby dark clouds and star-forming regions (Tamura 1988). Particularly, the magnetic field structure in the denser regions of the clouds are well revealed in Heiles Cloud 2 in Taurus, ρ Oph core, and NGC1333 region in Perseus (Tamura et al. 1987; Sato et al. 1988; Tamura et al. 1988). This survey also suggests an interesting geometrical relationship between magnetic field and star-formation: the IR polarization of young stellar sources associated with mass outflow phenomena is perpendicular to the magnetic fields. This relationship suggests a presence of circumstellar matter (probably dust disk) with its plane perpendicular to the ambient magnetic field. Combining with another geometrical relationship that the elongation of the denser regions of the cloud is perpendicular to the magnetic field, the geometry suggests that the cloud contraction and subsequent star-formation have been strongly affected by the magnetic fields. Thus, it is important to study the universality of such geometrical relationship between IR polarization of young stellar sources and magnetic fields. In this paper, we report the results on a 2 micron polarization survey of 39 T Tauri stars, 8 young stellar objects and 11 background field stars in Taurus dark cloud complex.

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