scholarly journals A Transparent Anode Array Detector for 3d Atom Probes

1998 ◽  
Vol 4 (S2) ◽  
pp. 80-81
Author(s):  
M. K. Miller
Keyword(s):  
Three Dimensional ◽  
Ccd Camera ◽  
Atom Probe ◽  
Single Atom ◽  
Array Detector ◽  
Detector Position ◽  
Spatial Coordinates ◽  
Position Sensitive ◽  
Position Sensitive Detectors ◽  
The Impact

In a three dimensional atom probe, the identity and spatial coordinates of the atoms field evaporated from the specimen are determined. Their identity is calculated from the flight time from the specimen to the single atom detector. The x and y coordinates of the atom in the specimen are determined from the coordinates of its impact position on the position-sensitive detector and the z coordinate is determined from its position in the evaporation sequence. These data may then be reconstructed to visualize and quantify the distribution of all the elements in the specimen. Several types of position-sensitive detectors have been used including a wedge-and-strip detector (position-sensitive atom probe), a 10 by 10 array of anodes (tomographic atom probe), and a gateable CCD camera (optical atom probe). The wedge-and strip and the CCD camera detectors both suffer from the limitation that if more than one atom strikes the detector on a field evaporation pulse then the impact positions cannot be determined in many cases.

Spatial and Compositional Biases Introduced by Position Sensitive Detection Systems in APT: A Simulation Approach

2019 ◽  
Vol 25 (2) ◽  
pp. 418-424 ◽  
Author(s):  
C. Bacchi ◽  
G. Da Costa ◽  
F. Vurpillot
Keyword(s):  
Detection System ◽  
Atom Probe ◽  
Signal Loss ◽  
Loss Mechanism ◽  
Multiple Events ◽  
Detection Systems ◽  
Statistical Correction ◽  
Position Sensitive ◽  
Position Sensitive Detectors ◽  
The Impact

AbstractDue to the low capacity of contemporary position-sensitive detectors in atom probe tomography (APT) to detect multiple events, material analyses that exhibit high numbers of multiple events are the most subject to compositional biases. To solve this limitation, some researchers have developed statistical correction algorithms. However, those algorithms are only efficient when one is confronted with homogeneous materials having nearly the same evaporation field between elements. Therefore, dealing with more complex materials must be accompanied by a better understanding of the signal loss mechanism during APT experiments. By modeling the evaporation mechanism and the whole APT detection system, it may be possible to predict compositional and spatial biases induced by the detection system. This paper introduces a systematic study of the impact of the APT detection system on material analysis through the development of a simulation tool.

Three-dimensional reconstruction of atomic-scale composition with the position-sensitive atom probe

1992 ◽  
Vol 50 (2) ◽  
pp. 1478-1479
Author(s):  
G.D.W. Smith ◽  
A. Cerezo ◽  
C.R.M. Grovenor ◽  
T.J. Godfrey ◽  
R.P. Setna
Keyword(s):  
Mass Spectrometer ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
Single Atom ◽  
Small Aperture ◽  
Dimensional Reconstruction ◽  
Position Sensitive ◽  
Atom Level ◽  
Scale Composition

The combination of a field ion microscope with a time-of-flight mass spectrometer provides the capability for chemical microanalysis at the single atom level. Such an instrument is termed an Atom Probe. Conventionally, the connection between the microscope and the mass spectrometer is made via a small aperture hole in the imaging screen. This defines a region on the specimen, typically about 2nm across, from which the analysis is obtained. The disadvantage of this arrangement is that other regions of the specimen cannot be examined, as ions from all but the selected area strike the image screen and therefore do not pass into the mass spectrometer. In order to overcome this problem, we have developed a version of the Atom Probe which incorporates a wide-angle position sensitive detector system. This instrument, which we have termed the POSAP, is shown schematically in figure 1. Typically, the field of view in this instrument is about 20nm across. The number of ions collected per atom layer removed from the specimen surface is therefore approximately 5,000.

Atom probes of the future

1994 ◽  
Vol 52 ◽  
pp. 834-835
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
D. J. Larson ◽  
L. M. Holzman
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
3D Images ◽  
New Era ◽  
Atom Probes ◽  
Position Sensitive ◽  
Third Dimension ◽  
Position Sensitive Detectors ◽  
Very High

Atom probe microscopy, which is based on the first ever atomic-scale imaging technique, field ion microscopy (FIM), has entered a new era in its development. Three-dimensional atom probes (3DAP) are now operating which produce 3D images with atomic scale resolution. It appears that the technology will soon be at hand to make 3DAPs do everything that their predecessor, the conventional atom probe, now does and also reach the third dimension. These microscopes will be simpler, smaller, faster, and much more powerful than the conventional atom probe. Several developments are responsible for this suggestion. 1) Rapid pulsing schemes are being developed which will make it possible to achieve on the order of 106 pulses per second. 2) Highspeed position-sensitive detectors (PSDs) have been designed which can detect several ions in a givenpulse with very high precision. 3) New specimen geometries will soon become possible which will revolutionize the atom probe. Let us consider the ramifications of each of these developments in turn.

Recent developments in position-sensitive atom-probe microanalysis

1994 ◽  
Vol 52 ◽  
pp. 828-829
Author(s):  
G. D. W. Smith ◽  
A. Cerezo ◽  
T. J. Godfrey ◽  
R. Setna ◽  
J. M. Hyde ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
Three Dimensions ◽  
Single Atom ◽  
Position Sensing ◽  
Recent Developments ◽  
Position Sensitive ◽  
New Generation ◽  
Serial Mode

The difficulties associated with the aperture geometry of the conventional atom probe have been overcome by the introduction of a new generation of wide-angle, single-atom sensitivity, positionsensitive detectors. With the aid of such detectors, it is now possible to map the locations and identitiesof atoms over regions of solid surface up to 50 nm in diameter. The nanometer-scale chemistry of successive atomic layers can be investigated during the process of field evaporation. We therefore have the new and exciting ability to investigate the atomic-scale chemistry of solids in three dimensions. The first three-dimensional atom probe is the PoSAP (Position Sensitive Atom Probe), developed at Oxford by Cerezo and Smith. In this instrument, position sensing is carried out by means of a wedge-and-strip anode assembly, located directly behind the double microchannel plate used for primary ion detection and time of flight measurement. The detector readout functions in serial mode. Only one ioncan be successfully detected and identified for each evaporation pulse which is applied to the specimen

Prospects for compositional imaging with the atom probe microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1616-1617
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
J. J. McCarthy ◽  
D. J. Larson ◽  
L. M. Holzman ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Compositional Analysis ◽  
Atom Probe ◽  
Atomic Scale ◽  
Probe Field ◽  
Acquisition Rate ◽  
3D Data ◽  
Probe Microscope ◽  
Position Sensitive ◽  
Field Ion Microscope

For the purposes of analytical characterization on the atomic scale, the ultimate instrument would identify every atom in a sample and determine its position with atomic-scale resolution. The recently developed positionsensitive atom probe (POSAP) comes as close as yet possible to this goal. This is the only experimental technique which can analyze the three-dimensional (3D) composition of a sample on a sub-nanometer scale.By adding a position-sensitive detector (PSD) to a conventional atom probe/field ion microscope, a 3D data structure with position-correlated compositional analysis is acquired. The 3D data are stored on a computer and may be examined for structural and compositional information at an atomic level. Note that, because it uses time-of-flight mass spectroscopy, all elements and their isotopes are detected in this way with equal proficiency. Usually, the evaporation rate is mediated by pulsing the field on the specimen. This approach, however, severely limits the data acquisition rate (about 1 atom per second) and mass resolution (about 1 part in 30).

Design and Development of Human Interface System with 3D Measurement Functions (Concept and Basic Experiments)

2012 ◽  
Vol 24 (1) ◽  
pp. 235-243 ◽  
Author(s):  
Jianming Yang ◽  
◽  
Takashi Imura
Keyword(s):  
Three Dimensional ◽  
Ccd Camera ◽  
Human Interface ◽  
System A ◽  
Interface System ◽  
Processing Module ◽  
Basic Functions ◽  
Position Sensitive ◽  
Basic Experiments ◽  
Interface Device

In this paper, an intelligent interface system for a wheelchair robot with an arm is described. The human interface system is comprised of an interface device and a signal processing module. An original idea of the authors, the interface device, which is a combination of a joystick, a Position Sensitive Detector (PSD), and a CCD camera, can realize threedimensional measurement in addition to performing the basic functions of a joystick. A principle for measuring three-dimensional positions and a method of presenting information by means of a Graphical User Interface (GUI) to verify and understand the instructions are proposed. To demonstrate the effectiveness of the intelligent operating system, a basic experiment is done.

Research on the Splitting Measurement Method of Space Position in Three-Dimensional Field

2010 ◽  
Vol 139-141 ◽  
pp. 2015-2018
Author(s):  
De Xi Wang ◽  
Qin Li ◽  
Fu Bao Li ◽  
Zong Ke Li
Keyword(s):  
Measurement Method ◽  
Optical Design ◽  
Three Dimensional ◽  
Ccd Camera ◽  
Spatial Location ◽  
Object Point ◽  
Position Measurement ◽  
Spatial Coordinates ◽  
Flat Mirror ◽  
Point Of Intersection

A research on measurement method of space position in three-dimensional field was demonstrated in this paper. According to the basic methods and principles of three-dimensional spatial position measurement, optical path of splitting design was used to divide an object point, through the red and green filters, into two beams of red and green, and then, through flat mirror, rectangular prism, cube prism and other optical design, it imaged on the same CCD camera film. Standard mesh was used to determine the relationship between two different spatial coordinates and the spatial pixel coordinates in the measurement space, and then the calibration relationship between object point coordinates and pixel coordinates were determined. This calibration relationship clear the error caused by the method of measurement and the measurement system. Through the determination algorithm of spatial location in three-dimensional field, the two corresponding lines of space was obtained, and its point of intersection is the spatial coordinate.

Characterisation of Ultrafine Microstructures Using a Position-Sensitive Atom Probe (POSAP)

1988 ◽  
Vol 132 ◽  
Author(s):  
Alfred Cerezo ◽  
Chris R. M. Grovenor ◽  
Mark G. Hetherington ◽  
Barbara A. Shollock ◽  
George D. W. Smith
Keyword(s):  
Solid Angle ◽  
Three Dimensional ◽  
Atom Probe ◽  
Field Evaporation ◽  
Sensitive Detector ◽  
Substantial Fraction ◽  
New Instrument ◽  
New Development ◽  
Position Sensitive ◽  
Permanent Magnet Materials

ABSTRACTA new development in the experimental techniques of atom probe microanalysis is described, which involves the use of a position sensitive detector system. This detector subtends a large solid angle (∼20°) at the specimen, and therefore permits the collection of ions from a substantial fraction of the whole surface area of the emitter. Progressive pulsed field evaporation leads to the construction of a three-dimensional map of the atomic chemistry of the specimen. The new instrument is ideally suited to the investigation of complex, ultrafine microstructures. Applications to the study of age-hardened aluminium alloys and Alnico permanent magnet materials are described.

scholarly journals Microtissue geometry and cell-generated forces drive patterning of liver progenitor cell differentiation in 3D

2020 ◽  
Author(s):  
Ian C. Berg ◽  
Erfan Mohagheghian ◽  
Krista Habing ◽  
Ning Wang ◽  
Gregory H. Underhill
Keyword(s):  
Cell Differentiation ◽  
Progenitor Cell ◽  
Three Dimensional ◽  
Stem Cell Differentiation ◽  
Cell Phenotype ◽  
Spatial Coordinates ◽  
Confocal Images ◽  
Tissue Geometry ◽  
The Impact ◽  
Liver Progenitor Cell

AbstractInvestigating the role of mechanical signaling on stem and progenitor cell differentiation in three-dimensional (3D) microenvironments is key to fully understanding these processes. Towards this, we implemented a hydrogel microwell based method to produce arrays of multicellular microtissues in constrained geometries, which cause distinct profiles of mechanical signals in 3D. We applied this platform to a model liver development system to investigate the impact of tissue geometry and mechanical stress on liver progenitor cell bipotential differentiation into hepatocyte-like and biliary-like cells. We fabricated 3D liver progenitor cell microtissues of varied geometries, including cylinder and toroid, and used image segmentation on confocal images to track individual single cell phenotype within defined spatial coordinates. These studies demonstrated patterning of hepatocytic differentiation to the outer shell of the cylinder and toroid microtissues, except at the inner diameter surface of the toroid tissues. Biliary differentiation was distributed throughout the microtissue interior regions and was additionally increased in toroid tissues compared to cylinder tissues. We used finite element modeling to predict stress distributions in these microtissues which demonstrated that cell-cell tension correlated with hepatocytic fate, while compression correlated with decreased hepatocytic differentiation and increased biliary differentiation. Overall, this combined approach that integrates microscale fabrication, imaging and analysis, and mechanical modeling serve as a demonstration of how microtissue geometry can drive patterning of mechanical stresses that regulate cell differentiation trajectories. It also can serve as a platform for the further investigation of tissue morphogenetic signaling mechanisms in the liver as well as other stem cell differentiation contexts.

Three Dimensional materials characterisation at ultrahigh resolution using a position-sensitive atom probe

1990 ◽  
Vol 48 (4) ◽  
pp. 408-409
Author(s):  
R A D Mackenzie ◽  
G D W Smith ◽  
A Cerezo ◽  
T J Godfrey ◽  
J.E. Brown
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Spatial Information ◽  
Three Dimensional ◽  
Atom Probe ◽  
Sensitive Detector ◽  
Channel Plate ◽  
Position Sensitive ◽  
20 Nm ◽  
Very High

The conventional atom probe field ion microscope permits very high resolution chemical information to be determined with a lateral spatial resolution of typically 2 nm. This spatial resolution is determined by the need to define the analysis area using an aperture. A recent development, the position sensitive atom probe (POSAP), has largely removed this limitation. In a conventional atom probe the ions passing through the aperture, which have come from a circular area of the order of 2 nm in diameter, travel along a long flight path where the mass to charge ratios are determined with high precision. In the position sensitive atom probe the aperture assembly, long flight tube and ion detector (a channel plate) are replaced with a position sensitive detector held at a known distance from the specimen surface. This detector consists of two parts, a channel plate component which permits the flight times (and hence mass to charge ratios) to be determined, and a wedge and strip anode which permits the position of the incoming ion to be calculated. This arrival position corresponds directly to the position on the specimen from which the ion came. The total field of view of the POSAP is a disc approximately 20 nm in diameter. With a conventional atom probe the data acquired during the evaporation sequence can be considered as a core extracted from the specimen, where the average composition as a function of depth is known. The position sensitive atom probe permits us to record data from a much wider core (20 nm rather than 2 nm in diameter), and also to retain the spatial information within the core. As the evaporation proceeds the two dimensional information yielded by the position sensitive detector builds up into a three dimensional block of data. We have, therefore, both chemical and spatial information in three dimensions at very high resolution from the sampled volume of material.

Sign in / Sign up

Export Citation Format

Share Document