High Resolution Current Imaging by Direct Magnetic Field Sensing

2003 ◽  
Author(s):  
S.I. Woods ◽  
Nesco M. Lettsome ◽  
A.B. Cawthorne ◽  
L.A. Knauss ◽  
R.H. Koch
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Spatial Resolution ◽  
Great Promise ◽  
Magnetoresistive Sensor ◽  
Magnetic Sensitivity ◽  
Current Lines ◽  
Scanning Squid ◽  
Scanning Fiber ◽  
Ferromagnetic Probe

Abstract Two types of magnetic microscopes have been investigated for use in high resolution current mapping. The scanning fiber/SQUID microscope uses a SQUID sensor coupled to a nanoscale ferromagnetic probe, and the GMR microscope employs a nanoscale giant magnetoresistive sensor. Initial scans demonstrate that these microscopes can resolve current lines less than 10 µm apart with edge resolution of 1 µm. These types of microscopes are compared with the performance of a standard scanning SQUID microscope and with each other with respect to spatial resolution and magnetic sensitivity. Both microscopes show great promise for identifying current defects in die level devices.

scholarly journals Novel Magnetic-Sensing Modalities with Nitrogen-Vacancy Centers in Diamond*

2021 ◽  
Author(s):  
Huijie Zheng ◽  
Arne Wickenbrock ◽  
Georgios Chatzidrosos ◽  
Lykourgos Bougas ◽  
Nathan Leefer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spatial Resolution ◽  
Quantum Coherence ◽  
Nitrogen Vacancy ◽  
Atomic Scale ◽  
Magnetic Sensing ◽  
Weak Magnetic Fields ◽  
Nitrogen Vacancy Centers ◽  
Magnetic Sensitivity ◽  
Nv Centers

In modern-day quantum metrology, quantum sensors are widely employed to detect weak magnetic fields or nanoscale signals. Quantum devices, exploiting quantum coherence, are inevitably connected to physical constants and can achieve accuracy, repeatability, and precision approaching fundamental limits. As a result, these sensors have shown utility in a wide range of research domains spanning both science and technology. A rapidly emerging quantum sensing platform employs atomic-scale defects in crystals. In particular, magnetometry using nitrogen-vacancy (NV) color centers in diamond has garnered increasing interest. NV systems possess a combination of remarkable properties, optical addressability, long coherence times, and biocompatibility. Sensors based on NV centers excel in spatial resolution and magnetic sensitivity. These diamond-based sensors promise comparable combination of high spatial resolution and magnetic sensitivity without cryogenic operation. The above properties of NV magnetometers promise increasingly integrated quantum measurement technology, as a result, they have been extensively developed with various protocols and find use in numerous applications spanning materials characterization, nuclear magnetic resonance (NMR), condensed matter physics, paleomagnetism, neuroscience and living systems biology, and industrial vector magnetometry. In this chapter, NV centers are explored for magnetic sensing in a number of contexts. In general, we introduce novel regimes for magnetic-field probes with NV ensembles. Specifically, NV centers are developed for sensitive magnetometers for applications where microwaves (MWs) are prohibitively invasive and operations need to be carried out under zero ambient magnetic field. The primary goal of our discussion is to improve the utility of these NV center-based magnetometers.

scholarly journals High spatial resolution magnetic mapping using ultra-high sensitivity scanning SQUID microscopy on a speleothem from the Kingdom of Tonga, southern Pacific

2020 ◽  
Author(s):  
Naoto Fukuyo ◽  
Hirokuni Oda ◽  
Yusuke Yokoyama ◽  
Geoffrey Clark ◽  
Yuhji Yamamoto
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Spatial Resolution ◽  
Remanent Magnetization ◽  
High Spatial Resolution ◽  
Radiometric Dating ◽  
Stable Conditions ◽  
Scanning Squid ◽  
Laminated Structures ◽  
Scanning Squid Microscopy

Abstract Speleothems can be an ideal archive of paleomagnetism because they retain continuous geomagnetic records in stable conditions and can be used for reliable radiometric dating using U-series and radiocarbon methods. However, their weak magnetic signals hinder the widespread use of this archive in the field of geoscience. While previous studies successfully reconstructed paleomagnetic signatures, including geomagnetic excursions, their time resolutions presented were still not reached to a sufficient level. Recently emerging scanning SQUID microscopy (SSM) in this field can image very weak magnetic fields while maintaining high spatial resolution that could likely overcome this obstacle. In this study, we employed SSM to conduct paleomagnetic measurements on a stalagmite collected at Anahulu cave in Tongatapu Island, the Kingdom of Tonga. The sliced sample to a thickness of ca. 0.2 mm was scan for NRM using SSM showed the influence of viscous remanent magnetization. The average measured magnetic field after 5 mT AF demagnetization is ca. 0.27 nT with a sensor-to-sample distance of ~200 µm. A stronger magnetic field (average: ca. 0.62 nT) was observed above the grayish surface layer, as compared to that of the white inner layer (average: ca. 0.09 nT) associated with the laminated structures of a speleothem at the submillimeter scale with the SSM. The magnetization of the speleothem sample calculated by an inversion of isothermal remanent magnetization (IRM) also suggests that magnetic mineral content in the surface layer is higher than the inner layer. This feature was further investigated by low-temperature magnetometry and was suggested that it contains magnetite, maghemite, and goethite. The first-order reversal curve (FORC) measurements and the decomposition of IRM curves show that this speleothem contains a mixture of magnetic minerals with different coercivities and domain states. The contribution from maghemite and goethite to the total magnetization of the grayish surface layer is much higher than the white inner layer. The speleothem retaining magnetically and visually two distinct layers indicates that the depositional environment was shifted when the surface layer was deposited and was likely changed to the oxidative environment.

The Optical Programme of the Culgoora Solar Observatory

1967 ◽  
Vol 1 (2) ◽  
pp. 39-40 ◽  
Author(s):  
R.G. Giovanelli
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Spatial Resolution ◽  
Solar Observatory ◽  
The Sun ◽  
Ionized Gas ◽  
Space And Time ◽  
Physical Quantities ◽  
Atmospheric Seeing

The Sun being a highly ionized gas, the basic physical quantities most needed for understanding solar phenomena are temperature, pressure (or density), velocity and magnetic field, together with their variations in space and time. The general aim at Culgoora is to secure observations from which these quantities may be derived (insofar as is practicable) simultaneously over extended solar regions. To do this has involved the development and use of filters of high spectral and spatial resolution, the study of atmospheric seeing and ways of securing high-resolution observations, and the study of methods of analysing observations to yield the physical quantities needed.

scholarly journals High spatial resolution magnetic mapping using ultra-high sensitivity scanning SQUID microscopy on a speleothem from the Kingdom of Tonga, southern Pacific

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Naoto Fukuyo ◽  
Hirokuni Oda ◽  
Yusuke Yokoyama ◽  
Geoffrey Clark ◽  
Yuhji Yamamoto
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Radiometric Dating ◽  
Magnetic Carriers ◽  
Stable Conditions ◽  
Scanning Squid ◽  
Laminated Structures ◽  
Scanning Squid Microscopy

AbstractSpeleothems are ideal archives of environmental magnetism and paleomagnetism, since they retain continuous magnetic signals in stable conditions and can be used for reliable radiometric dating using U-series and radiocarbon methods. However, their weak magnetic signals hinder the widespread use of this archive in the field of geoscience. While previous studies successfully reconstructed paleomagnetic signatures and paleoenvironmental changes, the time resolutions presented were insufficient. Recently emerging scanning SQUID microscopy (SSM) in this field can image very weak magnetic fields while maintaining high spatial resolution that could likely overcome this obstacle. In this study, we employed SSM for high spatial resolution magnetic mapping on a stalagmite collected at Anahulu cave in Tongatapu Island, the Kingdom of Tonga. The average measured magnetic field after 5 mT alternating field demagnetization is ca. 0.27 nT with a sensor-to-sample distance of ~ 200 µm. A stronger magnetic field (average: ca. 0.62 nT) was observed above the grayish surface layer compared to that of the white inner part (average: ca. 0.09 nT) associated with the laminated structures of the speleothem at the submillimeter scale, which scanning resolution of the SSM in this study is comparable to the annual growth rates of the speleothem. The magnetization of the speleothem sample calculated from an inversion of isothermal remanent magnetization (IRM) also suggests that the magnetic mineral content in the surface layer is higher than the inner part. This feature was further investigated by low-temperature magnetometry. Our results show that the main magnetic carriers of the speleothem under study are magnetite and maghemite and it can contain hematite or ε-Fe2O3. The first-order reversal curve (FORC) measurements and the decomposition of IRM curves show that this speleothem contains a mixture of magnetic minerals with different coercivities and domain states. The contribution from maghemite to the total magnetization of the grayish surface layer was much higher than the white inner part. Such differences in magnetic mineralogy of the grayish surface layer from that of the inner part suggest that the depositional environment shifted and was likely changed due to the oxidative environment.

scholarly journals Mapping Population Distribution from High Resolution Remotely Sensed Imagery in a Data Poor Setting

2018 ◽  
Vol 10 (9) ◽  
pp. 1409 ◽  
Author(s):  
Sophie Mossoux ◽  
Matthieu Kervyn ◽  
Hamid Soulé ◽  
Frank Canters
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Population Distribution ◽  
Remotely Sensed ◽  
Great Promise ◽  
Remotely Sensed Imagery ◽  
Combining Data ◽  
Neighborhood Level

Accurate mapping of population distribution is essential for policy-making, urban planning, administration, and risk management in hazardous areas. In some countries, however, population data is not collected on a regular basis and is rarely available at a high spatial resolution. In this study, we proposed an approach to estimate the absolute number of inhabitants at the neighborhood level, combining data obtained through field work with high resolution remote sensing. The approach was tested on Ngazidja Island (Union of the Comoros). A detailed survey of neighborhoods at the level of individual dwellings, showed that the average number of inhabitants per dwelling was significantly different between buildings characterized by a different roof type. Firstly, high spatial resolution remotely sensed imagery was used to define the location of individual buildings, and second to determine the roof type for each building, using an object-based classification approach. Knowing the location of individual houses and their roof type, the number of inhabitants was estimated at the neighborhood level using the data on house occupancy of the field survey. To correct for misclassification bias in roof type discrimination, an inverse calibration approach was applied. To assess the impact of variations in average dwelling occupancy between neighborhoods on model outcome, a measure of the degree of confidence of population estimates was calculated. Validation using the leave-one-out approach showed low model bias, and a relative error at the neighborhood level of 17%. With the increasing availability of high resolution remotely sensed data, population estimation methods combining data from field surveys with remote sensing, as proposed in this study, hold great promise for systematic mapping of population distribution in areas where reliable census data are not available on a regular basis.

scholarly journals Quantifying Global and Random Uncertainties in High Resolution Global Geomagnetic Field Models Used for Directional Drilling

2021 ◽  
pp. 1-10
Author(s):  
Ciaran D. Beggan ◽  
Susan Macmillan ◽  
William J. Brown ◽  
Steve J. Grindrod
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Collision Avoidance ◽  
Spatial Resolution ◽  
Error Model ◽  
Small Scale ◽  
Magnetic Survey ◽  
Positional Error ◽  
Wide Range ◽  
Random Uncertainties

Summary Total field strength, declination, and dip angle of the Earth's magnetic field, in conjunction with gravity, are used by magnetic-survey tools to determine a wellbore's location. Magnetic field values may be obtained from global models that, depending on the model, have a wide range of spatial resolution at the Earth's surface from large scale (3000 km) to small scale (28 km). The magnetic field varies continuously in both time and space, so no model can fully capture the complexity of all sources; hence, there are uncertainties associated with the values provided. The SPE Wellbore Positioning Technical Section/Industry Steering Committee on Wellbore Surveying Accuracy (ISCWSA) published their original measurement-while-drilling (MWD) error model in 2000. Such models and uncertainties define positional error ellipsoids along the wellbore, which assist the driller in achieving their geological target, in addition to aiding collision avoidance. With the recent update to Revision 5 of the ISCWSA error model, we have reassessed the uncertainties associated with our latest high-resolution global magnetic field model. We describe the derivation of location-specific global and random uncertainties for use with predicted geomagnetic values from high-resolution models within magnetic MWD survey-tool-error models. We propose a sophisticated approach to provide realistic values at different locations around the globe; for example, we determine separate errors for regions where the models have high spatial resolution from aeromagnetic data compared to regions where only satellite data are available. The combined uncertainties are freely available via a web service with which the user can also see how they vary with time. The use of the revised uncertainty values in the MWD-error model, in most cases, reduces the positional error ellipsoids and allows better use of the increased accuracy from recent improvements in geomagnetic modeling. This is demonstrated using the new uncertainty values in the MWD-error model for three standard ISCWSA well profiles. A fourth theoretical well offshore Brazil where the vertical magnetic field is weak shows that with drillstring interference correction relying on the more uncertain magnetic dip, the positional error ellipsoids can increase. This is clearly of concern for attaining geological targets and collision avoidance.

scholarly journals High spatial resolution magnetic mapping using ultra-high sensitivity scanning SQUID microscopy on a speleothem from the Kingdom of Tonga, southern Pacific

2020 ◽  
Author(s):  
Naoto Fukuyo ◽  
Hirokuni Oda ◽  
Yusuke Yokoyama ◽  
Geoffrey Clark ◽  
Yuhji Yamamoto
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Spatial Resolution ◽  
Remanent Magnetization ◽  
High Spatial Resolution ◽  
Radiometric Dating ◽  
Stable Conditions ◽  
Scanning Squid ◽  
Laminated Structures ◽  
Scanning Squid Microscopy

Abstract Speleothems are an ideal archive of paleomagnetism since they retain continuous geomagnetic records in stable conditions and can be used for reliable radiometric dating using U-series and radiocarbon methods. However, their weak magnetic signals hinder the widespread use of this archive in the field of geoscience. While previous studies successfully reconstructed paleomagnetic signatures, including geomagnetic excursions, the time resolutions presented were not sufficient. Recently emerging scanning SQUID microscopy (SSM) in this field can image very weak magnetic fields while maintaining high spatial resolution that could likely overcome this obstacle. In this study, we employed SSM for paleomagnetic measurements on a stalagmite collected at Anahulu cave in Tongatapu Island, the Kingdom of Tonga. The samples were sliced to a thickness of ca. 0.2 mm and scanned for NRM using SSM, and the signal provides the indications of the influence from viscous remanent magnetization. It was thus removed by alternating field demagnetization (AFD) at 5mT. The average measured magnetic field after 5 mT AFD is ca. 0.27 nT with a sensor-to-sample distance of ~200 µm. A stronger magnetic field (average: ca. 0.62 nT) was observed above the grayish surface layer compared to that of the white inner layer (average: ca. 0.09 nT) associated with the laminated structures of a speleothem at the submillimeter scale with the SSM. The magnetization of the speleothem sample calculated by an inversion of isothermal remanent magnetization (IRM) also suggests that magnetic mineral content in the surface layer is higher than the inner layer. This feature was further investigated by low-temperature magnetometry. The results reveal that it contains magnetite and maghemite. The first-order reversal curve (FORC) measurements and the decomposition of IRM curves show that this speleothem contains a mixture of magnetic minerals with different coercivities and domain states. The contribution from maghemite to the total magnetization of the grayish surface layer is much higher than the white inner layer. The gray and white-colored layers of the speleothem retaining magnetically distinct characters indicates that the depositional environment was shifted when the surface layer was deposited and was likely changed to the oxidative environment.

Imaging of ferroelectric domain walls by electron holography

1992 ◽  
Vol 50 (1) ◽  
pp. 246-247
Author(s):  
Xiao Zhang
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Object Wave ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Quantitative Measurements ◽  
Resolution Imaging ◽  
Electron Microscopes

Electron holography has recently been available to modern electron microscopy labs with the development of field emission electron microscopes. The unique advantage of recording both amplitude and phase of the object wave makes electron holography a effective tool to study electron optical phase objects. The visibility of the phase shifts of the object wave makes it possible to directly image the distributions of an electric or a magnetic field at high resolution. This work presents preliminary results of first high resolution imaging of ferroelectric domain walls by electron holography in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls.

A Super-High-Resolution HVEM (H-1500) Newly Installed in NIRIM

1990 ◽  
Vol 48 (1) ◽  
pp. 142-143
Author(s):  
S. Horiuchi ◽  
Y. Matsui
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Inorganic Materials ◽  
Electron Gun ◽  
Resolving Power ◽  
National Budget ◽  
Voltage Electron ◽  
Specimen Holder ◽  
The Magnetic Field

A new high-voltage electron microscope (H-1500) specially aiming at super-high-resolution (1.0 Å point-to-point resolution) is now installed in National Institute for Research in Inorganic Materials ( NIRIM ), in collaboration with Hitachi Ltd. The national budget of about 1 billion yen including that for a new building has been spent for the construction in the last two years (1988-1989). Here we introduce some essential characteristics of the microscope.(1) According to the analysis on the magnetic field in an electron lens, based on the finite-element-method, the spherical as well as chromatic aberration coefficients ( Cs and Cc ). which enables us to reach the resolving power of 1.0Å. have been estimated as a function of the accelerating As a result of the calculaton. it was noted that more than 1250 kV is needed even when we apply the highest level of the technology and materials available at present. On the other hand, we must consider the protection against the leakage of X-ray. We have then decided to set the conventional accelerating voltage at 1300 kV. However. the maximum accessible voltage is 1500 kV, which is practically important to realize higher voltage stabillity. At 1300 kV it is expected that Cs= 1.7 mm and Cc=3.4 mm with the attachment of the specimen holder, which tilts bi-axially in an angle of 35° ( Fig.1 ). In order to minimize the value of Cc a small tank is additionally placed inside the generator tank, which must serve to seal the magnetic field around the acceleration tube. An electron gun with LaB6 tip is used.

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