scholarly journals Optical Design and Optimization with Genetic Algorithm for High-Resolution Optics Applied to Underwater Remote-Sensing

2021 ◽  
Vol 11 (21) ◽  
pp. 10200
Author(s):  
Chun-Feng Chou ◽  
Cheng-Mu Tsai ◽  
Chao-Hsien Chen ◽  
Yung-Hao Wong ◽  
Yi-Chin Fang ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
High Resolution ◽  
Shallow Water ◽  
Deep Water ◽  
Optical Design ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Zoom Lens ◽  
Underwater Photography ◽  
Underwater Camera

In fields such as biology, archeology, and industry, underwater photogrammetry can be achieved using consumer-grade equipment. However, camera operations underwater differ considerably from those on land because underwater photogrammetry involves different optical phenomena. On the basis of the requirements and specifications of the marine vessel Polaris, we developed a novel underwater camera with prime and zoom lenses and a high resolving power. The camera can be used in the spectrum in shallow water and the blue–green spectrum in deep water. In the past, ordinary cameras would be placed in waterproof airtight boxes for underwater photography. These cameras were not optimized to the underwater spectrum and environment, resulting in no breakthroughs in resolving power. Furthermore, the use of the blue spectrum greatly increases during underwater and particularly deep-water surveying. Chromatic aberration and focus-point displacement generated by the shift from the shallow-water spectrum to the blue–green spectrum in deep water makes universal underwater photography even more difficult. Our proposed optical design aimed to overcome such challenges for the development of a high-resolution underwater surveying camera. We designed a prime lens and a zoom lens. We adopted a waterproof dome window on the outer surface as the basic structure and optimized it in accordance with the conditions of different water depths and spectra to obtain distortion within ±2% and high-resolution underwater imaging quality. For the zoom lens design, we employed a genetic algorithm in Zemax to attenuate chromatic aberration as a kind of extended optimization. This novel optical design that can be used in all waters is expected to greatly reduce the volume and weight of conventional underwater cameras by more than 50% and 60%, respectively, and increase their resolving power by 30–40%.

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.

A high resolution multi-turn TOF mass analyzer

2019 ◽  
Vol 34 (36) ◽  
pp. 1942005 ◽  
Author(s):  
Vyacheslav Shchepunov ◽  
Michael Rignall ◽  
Roger Giles ◽  
Ryo Fujita ◽  
Hiroaki Waki ◽  
...  
Keyword(s):  
High Resolution ◽  
Mirror Symmetry ◽  
Rotational Symmetry ◽  
Optical Design ◽  
Resolving Power ◽  
Mass Analyzer ◽  
Rotationally Symmetric ◽  
Mass Resolving Power ◽  
Operational Modes ◽  
Drift Direction

An ion optical design of a high resolution multi-turn time-of-flight mass analyzer (MT-TOF MA) is presented. The analyzer has rotationally symmetric main electrodes with additional mirror symmetry about a mid-plane orthogonal to the axis of symmetry. Rotational symmetry allows a higher density of turns in the azimuthal (drift) direction compared to MT-TOF MAs that are linearly extended in the drift direction. Mirror symmetry about a mid-plane helps to achieve a high spatial isochronicity of the ions’ motion. The analyzer comprises a pair of polar-toroidal sectors S1 and S3, a pair of polar (trans-axial) lenses, and a pair of conical lenses for longitudinal and lateral focusing. A toroidal sector S2 located at the mid-plane of the analyzer has a set of embedded drift focusing segments providing focusing and spatial isochronicity in the drift direction. The ions’ drift in the azimuthal direction can be reversed by using dedicated reversing deflectors. This gives the possibility of several operational modes with different numbers of turns and passes in the drift direction. According to numerical simulations, the mass resolving power of the analyzer ranges from [Formula: see text]40 k (fwhm) at small (typically below ten) numbers of turns to [Formula: see text]450 k (fwhm) at 96 turns.

The crystal structure of 4Nb2O5.9WO3 studied by 1 MV high-resolution electron microscopy

1978 ◽  
Vol 34 (6) ◽  
pp. 939-946 ◽  
Author(s):  
S. Horiuchi ◽  
K. Muramatsu ◽  
Y. Matsui
Keyword(s):  
High Resolution ◽  
Tungsten Bronze ◽  
Chromatic Aberration ◽  
High Resolution Electron Microscopy ◽  
Resolving Power ◽  
Tungsten Bronze Structure ◽  
Tetragonal Tungsten Bronze ◽  
Resolution Electron ◽  
Computer Calculations ◽  
High Resolution Electron Microscope

Images of pale yellow crystals of 4Nb2O5. 9WO3, obtained with a 1 MV high-resolution electron microscope revealed twinned domains of a tetragonal tungsten bronze structure with a superlattice of 3 x 1 subcells. Comparison with computer calculations suggests that the cations filling the pentagonal tunnels include both Nb and W. Crystals darkened due to reduction on longer heating included no domains and were sensitive to electron irradiation; cations were knocked on from the filled to the vacant pentagonal tunnels. This suggests that some oxygens are released from the -M-O-M-O-M- strings in the tunnels on reduction to weaken the chemical bonding. The number of deficient oxygens is known from the weight gain on oxidizing the crystal. Some additional experiments reveal that there is no '6Nb2O5. 1 IWO3' phase. The resolving power of the present microscope is discussed on the basis of the analysis of the chromatic aberration.

scholarly journals Development of the Soft X-ray AGM–AGS RIXS beamline at the Taiwan Photon Source

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
A. Singh ◽  
H. Y. Huang ◽  
Y. Y. Chu ◽  
C. Y. Hua ◽  
S. W. Lin ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical Design ◽  
Charge Density Waves ◽  
Resolving Power ◽  
X Rays ◽  
X Ray ◽  
Compensation Principle ◽  
Wide Range ◽  
Energy Compensation ◽  
Photon Source

We report on the development of a high-resolution and highly efficient beamline for soft X-ray resonant inelastic X-ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angles over a wide range. Several high-precision instruments developed in-house for this beamline are described briefly. The best energy resolution obtained from this AGM–AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2 × 104, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impact of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, i.e. La2–x Sr x CuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge-density waves.

scholarly journals Extreme High-Resolution SEM: A Paradigm Shift

2008 ◽  
Vol 16 (4) ◽  
pp. 24-29 ◽  
Author(s):  
Richard Young ◽  
Todd Templeton ◽  
Laurent Roussel ◽  
Ingo Gestmann ◽  
Gerard van Veen ◽  
...  
Keyword(s):  
High Resolution ◽  
Paradigm Shift ◽  
Optical Design ◽  
Chromatic Aberration ◽  
Scanning Transmission Electron Microscope ◽  
Performance Category ◽  
Design Elements ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron

“Extreme high-resolution” (XHR) scanning electron microscopy (SEM) has the potential to change the way we look at SEM. Anyone in the SEM world knows that you don't do high-resolution SEM at low accelerating voltages because of chromatic aberration limitations. The XHR design offers a new way to deal with chromatic aberration and realize the huge benefit of reduced beam penetration.The new Magellan 400 SEM family is the first to offer subnanometer resolution over the entire electron energy range from 1 keV to 30 keV, effectively establishing a new performance category known as XHR SEM (Figure 1). To achieve this unprecedented performance, the Magellan combines novel electron optical design elements with technologies developed for the industry-leading Titan (scanning) transmission electron microscope (S/TEM) and DualBeam (focused ion /SEM) platforms.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

1975 ◽  
Vol 33 ◽  
pp. 664-665
Author(s):  
Mircea Fotino
Keyword(s):  
Experimental Approach ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Biological Research ◽  
Specimen Thickness ◽  
Resolution Limit ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

Voltage-center COMA-free alignment for high-resolution Electron Microscopy

1994 ◽  
Vol 52 ◽  
pp. 410-411
Author(s):  
K. Ishizuka ◽  
K. Shirota
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Incident Beam ◽  
Chromatic Aberration ◽  
High Resolution Electron Microscopy ◽  
Beam Deflection ◽  
Objective Lens ◽  
Main Magnetic Field ◽  
Beam Direction ◽  
Resolution Electron

In a conventional alignment for high-resolution electron microscopy, the specimen point imaged at the viewing-screen center is made dispersion-free against a voltage fluctuation by adjusting the incident beam direction using the beam deflector. For high-resolution works the voltage-center alignment is important, since this alignment reduces the chromatic aberration. On the other hand, the coma-free alignment is also indispensable for high-resolution electron microscopy. This is because even a small misalignment of the incident beam direction induces wave aberrations and affects the appearance of high resolution electron micrographs. Some alignment procedures which cancel out the coma by changing the incident beam direction have been proposed. Most recently, the effect of a three-fold astigmatism on the coma-free alignment has been revealed, and new algorithms of coma-free alignment have been proposed.However, the voltage-center and the coma-free alignments as well as the current-center alignment in general do not coincide to each other because of beam deflection due to a leakage field within the objective lens, even if the main magnetic-field of the objective lens is rotationally symmetric. Since all the proposed procedures for the coma-free alignment also use the same beam deflector above the objective lens that is used for the voltage-center alignment, the coma-free alignment is only attained at the sacrifice of the voltage-center alignment.

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