scholarly journals Progress In Design and Applications Of CCD Cameras For Electron Microscopy

1995 ◽  
Vol 3 (10) ◽  
pp. 12-13 ◽  
Author(s):  
Kenneth H. Downing
Keyword(s):  
High Sensitivity ◽  
Ccd Cameras ◽  
Video Cameras ◽  
Quantum Leap ◽  
Fluorescent Screen ◽  
Lower Beam ◽  
Video Systems ◽  
On Line ◽  
Specimen Quality ◽  
Electron Microscopes

Over the last several years the long-awaited revolution in direct-digital readout systems has begun, with the introduction of efficient slow-scan CCD cameras. Earlier, the introduction of video cameras to electron microscopes had brought a quantum leap in the speed and efficiency of carrying out a host of operations. The high sensitivity of the video cameras provided the ability to see the image in much more detail and at a lower beam intensity than had been previously possible by viewing the fluorescent screen. The ability to assess, on line, characteristics such as specimen quality and image focus, even qualitatively, gave feedback to the operator that previously took hours to obtain. Due to the low resolution of these video systems, however, they were rarely useful for data recording.

Progress in design and applications of CCD cameras for Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 6-7
Author(s):  
Kenneth H. Downing
Keyword(s):  
High Sensitivity ◽  
Data Recording ◽  
Ccd Cameras ◽  
Video Cameras ◽  
Quantum Leap ◽  
Fluorescent Screen ◽  
Video Systems ◽  
On Line ◽  
Specimen Quality ◽  
Electron Microscopes

Over the last several years the long-awaited revolution in direct-digital readout systems has begun, with the introduction of efficient slow-scan CCD cameras. Earlier, the introduction of video cameras to electron microscopes had brought a quantum leap in the speed and efficiency of carrying out a host of operations. The high sensitivity of the video cameras provided the ability to see the image in much more detail and at a lower beam intensity than had been possible previously by viewing the fluorescent screen. The ability to assess, on line, characteristics such as specimen quality and image focus, even qualitatively, gave feedback to the operator that previously took hours to obtain. Due to the low resolution of these video systems, however, they were rarely useful for data recording.The current generation of CCD cameras goes a long way toward meeting the needs of data recording in many, though certainly not all, applications.

MTF restoration with slow-scan CCD cameras

1993 ◽  
Vol 51 ◽  
pp. 262-263 ◽  
Author(s):  
P.E. Mooney ◽  
W.J. de Ruijter ◽  
O.L. Krivanek
Keyword(s):  
Quality Data ◽  
Reference Image ◽  
Ccd Cameras ◽  
Fast Electrons ◽  
Gain Variation ◽  
Transmission Electron ◽  
On Line ◽  
Electron Image ◽  
Exposure Levels ◽  
Electron Microscopes

Slow-scan CCD cameras (SSCs) attached to transmission electron microscopes (TEMs) are proving invaluable in the acquisition of TEM images and in providing high quality data for on-line analysis and autotuning procedures. When equipped with a sensitive phosphor and an efficient fiber-optical coupling, they are able to record the arrival of single fast electrons. At more typical exposure levels of 10 -1000 fast electrons per pixel, they are able to capture images while adding less noise than the Poisson noise inherent in any electron image.The raw images captured by the SSC suffer from various defects, but these can be corrected on-line in the computer used to record the images. The most familiar defect is the pixel-to-pixel gain variation, which is readily corrected by capturing a gain-reference image and then performing on-line gain-normalization. Another significant defect in raw images is that the signal due to each arriving electron is spread overseveral pixels.

Is Digital Imaging Ready to Replace Photographic Films ?

1997 ◽  
Vol 3 (S2) ◽  
pp. 1107-1108
Author(s):  
M. Pan
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Dynamic Range ◽  
Computer Control ◽  
Remote Site ◽  
Ccd Cameras ◽  
On Line ◽  
Pixel Image ◽  
Electron Microscopes ◽  
New Generation

The new generation of cooled slow-scan CCD cameras (SSC) have demonstrated the superior properties to conventional photographic films in sensitivity, resolution, dynamic range, linearity, and on-line availability. Furthermore the digital imaging capability as offered by SSC cameras facilitates image processing and quantitative analysis. Other advantages of digital imaging include easy archiving, sending images to a remote site via high speed communication network, and carrying out telemicroscopy, etc. Today, many laboratories in electron microscopy have already abandoned the traditional “dark room” and switched to digital imaging. One of the obstacle in replacing photographic films with digital imaging is the fact that current SSC cameras (e.g. 1024 × 1024 pixels) do not have enough pixels as compared with the film. Therefore the resolution is often compromised with the field of view when using CCD cameras.With computer control of electron microscopes and the use of CCD cameras, we have developed automated “montage” software that can automatically shift and acquire images from a microscope, and automatically perform pixel-to-pixel image alignment to form a montage. The size of the montage is defined by the number of images acquired in both horizontal and vertical directions.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

1968 ◽  
Vol 26 ◽  
pp. 316-317
Author(s):  
George Christov ◽  
Bolivar J. Lloyd
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Voltage ◽  
High Intensity ◽  
Electron Gun ◽  
Tungsten Filament ◽  
Fluorescent Screen ◽  
Electron Microscopes ◽  
Pass Through ◽  
Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

Exit-surface wave reconstruction using a focal series

1992 ◽  
Vol 50 (2) ◽  
pp. 988-989
Author(s):  
W.J. de Ruijter ◽  
M.R. McCartney ◽  
David J. Smith ◽  
J.K. Weiss
Keyword(s):  
Surface Wave ◽  
Spherical Aberration ◽  
Data Extraction ◽  
High Sensitivity ◽  
Geometric Distortion ◽  
Variation Method ◽  
Objective Lens ◽  
Immediate Reconstruction ◽  
Exit Surface ◽  
Electron Microscopes

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

A Hierarchical Access Control Scheme Based on Lagrange Interpolation and ELGamal Algorithm with Numerical Experiments

2013 ◽  
Vol 385-386 ◽  
pp. 1705-1707
Author(s):  
Tzer Long Chen ◽  
Yu Fang Chung ◽  
Jian Mao Hong ◽  
Jeng Hong Jhong ◽  
Chin Sheng Chen ◽  
...  
Keyword(s):  
Access Control ◽  
Lagrange Interpolation ◽  
Control Mechanism ◽  
Key Generation ◽  
Electronic Documents ◽  
Control Scheme ◽  
Video Systems ◽  
Efficient Scheme ◽  
On Line ◽  
Access Control Mechanism

It is important to notice that the access control mechanism has been widely applied in various areas, such as on-line video systems, wireless network, and electronic documents. We propose an access control mechanism which is constructed based on two mathematical fundamentals: Lagrange interpolation and ElGamal algorithm. We conduct performance analysis to compare the efficiency of our proposed scheme with that of several related published schemes in both key generation phase and key derivation phase. Our new scheme is proven to be more efficient. It is shown, as expected, a more efficient scheme provides relatively less security and a more secure scheme is relatively less efficient for private keys of the same size.

Electric birefringence for monitoring size changes in clay suspensions

Clay Minerals ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 549-556 ◽  
Author(s):  
I. C. Hinds ◽  
P. J. Ridler ◽  
B. R. Jennings
Keyword(s):  
Colloidal Suspensions ◽  
High Sensitivity ◽  
Ultrasonic Field ◽  
Decay Rates ◽  
Continuous Change ◽  
Particle Size Range ◽  
On Line ◽  
Clay Suspensions ◽  
Pulsed Fields ◽  
And Control

AbstractThe growth and decay rates of rapid, induced electro-optical phenomena in dilute colloidal suspensions are characteristic of the geometry of the solute particles. The speed of measurement renders such methods especially relevant for fast, in situ analyses of the size and size distribution of colloids in practical, industrial situations where these properties may be undergoing continuous change. The principles of the measurement of electrically induced birefringence using pulsed fields is outlined and used to study vermiculite suspensions as they undergo size reduction in an ultrasonic field. The high sensitivity of the method to both the particle size range and the form of the distribution function is indicated. The use of the method for on-line monitoring of dilute mineral suspensions for the indication and control of aggregated, dissolving or growing media is discussed.

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