Effect of atmospheric turbulence on the spot size of a radio-acoustic sounding system: A calculation revisited

Radio Science ◽  
1996 ◽  
Vol 31 (6) ◽  
pp. 1531-1540 ◽  
Author(s):  
Richard J. Lataitis ◽  
Steven F. Clifford
Keyword(s):  
Atmospheric Turbulence ◽  
Spot Size ◽  
Acoustic Sounding ◽  
System A

Spot size of the radar return from a radar-acoustic sounding system (RASS) due to atmospheric refractive turbulence

Radio Science ◽  
1978 ◽  
Vol 13 (6) ◽  
pp. 985-989 ◽  
Author(s):  
S. F. Clifford ◽  
Ting-i Wang ◽  
J. T. Priestley
Keyword(s):  
Spot Size ◽  
Acoustic Sounding

DEVELOPMENT OF THE HIROSHIMA PROTON MICROBEAM SYSTEM

1994 ◽  
Vol 04 (02n03) ◽  
pp. 75-79
Author(s):  
K. IWATANI ◽  
T. MIZUOKA ◽  
F. NISHIYAMA ◽  
S. TANAKA ◽  
K. FUKAMI ◽  
...  
Keyword(s):  
Detection System ◽  
Spot Size ◽  
Target Chamber ◽  
Scanning System ◽  
Beam Spot ◽  
System A ◽  
Beam Spot Size ◽  
Electron Detection ◽  
Under Construction ◽  
Mev Protons

A proton microbeam system is under construction for a 2.5 MV Van de Graaff in Hiroshima University. We have prepared and tested a proto-type target chamber, a beam scanning system, a secondary electron detection system and software for scanner control and data acquisition. The minimum beam spot size obtained so far is 3.0 µm×2.7 µm (FWHM) for 2 MeV protons.

scholarly journals Design and Characterization of a 7.2 KW Solar Simulator

2015 ◽  
Author(s):  
Antoine Boubault ◽  
Julius Yellowhair ◽  
Clifford K. Ho
Keyword(s):  
Computer Aided Design ◽  
Spot Size ◽  
Solar Simulator ◽  
System A ◽  
Metal Halide Lamp ◽  
Model Predictions ◽  
Average Irradiance ◽  
Aided Design ◽  
Good Agreement

A 7.2 kW radiative solar simulator was designed in order to perform accelerated testing on absorber materials for concentrating solar power (CSP) technologies. Computer-aided design (CAD) software integrating a ray-tracing tool was used to select appropriate components and optimize their positioning in order to achieve the desired concentration. The simulator comprises four identical units, each made out of an ellipsoidal reflector, a metal halide lamp and an adjustable holding system. A single unit was characterized and shows an experimental average irradiance of 257 kW m−2 on a 25.4 mm (1 inch) diameter spot. Shape, spot size and average irradiance are in good agreement with the model predictions. The innovative four-lamp solar simulator potentially demonstrates peak irradiance of 1140 kW m−2 and average irradiance of 878 kW m−2 over a 25.4 mm diameter spot. The costs per radiative and electric watt are calculated at $2.31 W−1 and $1.99 W−1, respectively.

Use of the argon surgical laser in neurosurgery

1984 ◽  
Vol 60 (3) ◽  
pp. 523-530 ◽  
Author(s):  
Stephen K. Powers ◽  
Michael S. B. Edwards ◽  
James E. Boggan ◽  
Lawrence H. Pitts ◽  
Philip H. Gutin ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Argon Laser ◽  
Spot Size ◽  
Neurosurgical Procedures ◽  
Entry Zone ◽  
Content Type ◽  
Root Entry Zone ◽  
System A ◽  
Surgical Laser ◽  
Proper Setting

✓ The argon surgical laser has been used in 68 neurosurgical procedures that included the removal of intracranial and intraspinal tumors, spinal cord fenestration for syringomyelia, and the production of dorsal root entry zone lesions. Characteristics that make the argon surgical laser a useful microneurosurgical instrument include the availability of a fiberoptic delivery system, a laser spot size that can be varied continuously between 0.15 and 1.5 mm, a single laser-aiming and treatment beam, the transmission of argon laser light through aqueous media such as irrigating or cerebrospinal fluids, and improved hemostasis compared to conventional techniques. The argon laser is limited primarily by its relatively low power output (less than 16 W), which makes the excision of large tumors difficult. However, even with these limitations, which can be used to advantage in the proper setting, the authors' laboratory and clinical experience suggests that the argon surgical laser may be useful in certain microneurosurgical operations.

scholarly journals Design and Characterization of a 7.2 kW Solar Simulator

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Antoine Boubault ◽  
Julius Yellowhair ◽  
Clifford K. Ho
Keyword(s):  
Computer Aided Design ◽  
Element Model ◽  
Spot Size ◽  
Labor Costs ◽  
Solar Simulator ◽  
Radiative Efficiency ◽  
System A ◽  
Average Irradiance ◽  
Aided Design

A 7.2 kW (electric input) solar simulator was designed in order to perform accelerated testing on absorber materials for concentrating solar power (CSP) technologies. computer-aided design (cad) software integrating a ray-tracing tool was used to select appropriate components and optimize their positioning in order to achieve the desired concentration. The simulator comprises four identical units, each made out of an ellipsoidal reflector, a metal halide lamp, and an adjustable holding system. A single unit was characterized and shows an experimental average irradiance of 257 kW m−2 on a 25.4 mm (1 in) diameter spot. Shape, spot size, and average irradiance are in good agreement with the model predictions, provided the emitting arc element model is realistic. The innovative four-lamp solar simulator potentially demonstrates peak irradiance of 1140 kW m−2 and average irradiance of 878 kW m−2 over a 25.4 mm diameter area. The electric-to-radiative efficiency is about 0.86. The costs per radiative and electric watt are calculated at $2.31 W−1 and $1.99 W−1, respectively. An upgraded installation including a sturdier structure, computer-controlled lamps, a more reliable lamp holding system, and safety equipment yields a cost per electric watt of about $3.60 W−1 excluding labor costs.

New Design for a Differentially Pumped Hydration Chamber for a Siemens IA

1971 ◽  
Vol 29 ◽  
pp. 44-45
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Electron Diffraction ◽  
Water Vapor Pressure ◽  
Biological Materials ◽  
Thin Membrane ◽  
Reliable System ◽  
System A ◽  
Water Films ◽  
Aperture Opening

Electron microscopy and diffraction of biological materials in the hydrated state requires the construction of a chamber in which the water vapor pressure can be maintained at saturation for a given specimen temperature, while minimally affecting the normal vacuum of the remainder of the microscope column. Initial studies with chambers closed by thin membrane windows showed that at the film thicknesses required for electron diffraction at 100 KV the window failure rate was too high to give a reliable system. A single stage, differentially pumped specimen hydration chamber was constructed, consisting of two apertures (70-100μ), which eliminated the necessity of thin membrane windows. This system was used to obtain electron diffraction and electron microscopy of water droplets and thin water films. However, a period of dehydration occurred during initial pumping of the microscope column. Although rehydration occurred within five minutes, biological materials were irreversibly damaged. Another limitation of this system was that the specimen grid was clamped between the apertures, thus limiting the yield of view to the aperture opening.

Remarks on the application of backscattered electron imaging (BEI) to the scanning electron microscopy (SEM) of biological structures

1983 ◽  
Vol 41 ◽  
pp. 484-487
Author(s):  
Etienne de Harven
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Spot Size ◽  
Primary Electron ◽  
Critical Point Drying ◽  
Cell Shapes ◽  
High Resolution Images ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron

Biological ultrastructures have been extensively studied with the scanning electron microscope (SEM) for the past 12 years mainly because this instrument offers accurate and reproducible high resolution images of cell shapes, provided the cells are dried in ways which will spare them the damage which would be caused by air drying. This can be achieved by several techniques among which the critical point drying technique of T. Anderson has been, by far, the most reproducibly successful. Many biologists, however, have been interpreting SEM micrographs in terms of an exclusive secondary electron imaging (SEI) process in which the resolution is primarily limited by the spot size of the primary incident beam. in fact, this is not the case since it appears that high resolution, even on uncoated samples, is probably compromised by the emission of secondary electrons of much more complex origin.When an incident primary electron beam interacts with the surface of most biological samples, a large percentage of the electrons penetrate below the surface of the exposed cells.

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

Image registration with a computer driven S.T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 98-99
Author(s):  
A.M.H. Schepman ◽  
J.A.P. van der Voort ◽  
J.E. Mellema
Keyword(s):  
Spot Size ◽  
Scanning Transmission Electron Microscope ◽  
Small Computer ◽  
Structural Studies ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Specimen Area ◽  
On Line ◽  
Minimum Distances

A Scanning Transmission Electron Microscope (STEM) was coupled to a small computer. The system (see Fig. 1) has been built using a Philips EM400, equipped with a scanning attachment and a DEC PDP11/34 computer with 34K memory. The gun (Fig. 2) consists of a continuously renewed tip of radius 0.2 to 0.4 μm of a tungsten wire heated just below its melting point by a focussed laser beam (1). On-line operation procedures were developped aiming at the reduction of the amount of radiation of the specimen area of interest, while selecting the various imaging parameters and upon registration of the information content. Whereas the theoretical limiting spot size is 0.75 nm (2), routine resolution checks showed minimum distances in the order 1.2 to 1.5 nm between corresponding intensity maxima in successive scans. This value is sufficient for structural studies of regular biological material to test the performance of STEM over high resolution CTEM.

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