Beam Scanning Method Research Articles

Effects of defining realistic compositions of the ocular melanoma on proton therapy.

Recent studies in eye plaque brachytherapy have shown a considerable difference between the dosimetric results using water phantom and a model of human eye containing realistic materials. In spite of this fact, there is a lack of simulation studies based on such a model in proton therapy literatures. In the presented work, the effect of utilizing an eye model with ocular media on proton therapy is investigated using the MCNPX Monte Carlo Code. Two different eye models are proposed to study the effect of defining realistic materials on dose deposition due to utilizing pencil beam scanning (PBS) method for proton therapy of ocular melanoma. The first model is filled with water, and the second one contains the realistic materials of tumor and vitreous. Spread out Bragg peaks (SOBP) are created to cover a typical tumor volume. Moreover, isodose curves are figured in order to evaluate planar variations of absorbed dose in two models. The results show that the maximum delivered dose in ocular media is approximately 12-32% more than in water phantom. Also it is found that using the optimized weighted beams in water phantom leads to disturbance of uniformity of SOBP in ocular media. Similar to the results reported in eye brachytherapy published papers, considering the ocular media in simulation studies leads to a more realistic assessment of sufficiency of the designed proton beam in tissue. This effect is of special importance in creating SOBP, as well as in delivered dose in the tumor boundaries in proton pencil beam scanning method.

Random Laser With Multiphase-Shifted Bragg Grating in Er/Yb-Codoped Fiber

A random fiber laser is demonstrated based on a 25-mm-long multiphase-shifted fiber Bragg grating fabricated in a highly Er/Yb-codoped fiber with the beam-scanning method. By inserting 20 phase errors with random amplitudes along the grating length and pumping it with a 980-nm laser diode, we achieved random laser output with high-optical signal-to-noise ratio up to 65 dB. The laser can be operated at either single- or dual-wavelength modes with changeable lasing wavelengths depending on the power of pump laser. The pump threshold is only 28 mW, and the output stability is greatly improved by immersing the active fiber in water. It is, to the best of our knowledge, the shortest random fiber laser reported so far, if only the effective part of the fiber is considered.

Microstructures of laser bonded SiC ceramics with Zr interlayers

SiC plates were bonded using a laser beam scanning method. As an interlayer material, a Zr sheet 0.4mm in thickness was used. Joining was performed at room temperature in air under atmospheric pressure. The interfacial microstructures along with their atomic compositions of the Zr/SiC reaction zone were analyzed. In the Zr side, diffused Si formed ZrSi2, Zr5Si3Cx, and Zr4Si phases. Carbide transformation was observed (Zr+C→ZrCx) near the Zr/SiC interface. No crystallographic orientation relationship was found in most of the grains; however, a boundary of ZrSi2 [100] parallel to Zr5Si3Cx[011¯1] was found in the observation. In the SiC side, penetrated Zr was found at up to 120μm from the Zr/SiC interface. The diffused Zr formed a silicon-rich metastable phase of ZrSiy (y>3.3).

A Beam Scanning Method based on the Helical Antenna for Space-based AIS

We investigate a strategy to address the problem of low ship detection probability of space-based Automatic Identification System (AIS). A directional AIS antenna and an innovative beam scanning method are proposed, which scan the antenna across a wide swath to provide complete coverage and maintain the advantage of a narrow footprint to reduce signal collision. Aiming at the mission requirement of global ship detection by the year 2016, the appropriate swath, the scanning range and the scanning rate were studied and designed in detail. Theoretical analysis and simulations showed that this scanning antenna can greatly improve ship detection probability and hold the detection probability at an average reporting interval from six to 15 seconds for most oceans when compared with the traditional fixed wide beam antenna. Furthermore, the detection capacity of this scanning antenna was little affected by the heights of different Low Earth Orbits. The results of this work show that the design of the helical antenna along with the beam scanning method can be considered as a building block of future space-based AIS.

MICROSTRUCTURE AND MECHANICAL STRENGTH OF SURFACE ODS TREATED ZIRCALOY-4 SHEET USING LASER BEAM SCANNING

The surface modification of engineering materials by laser beam scanning (LBS) allows the improvement of properties in terms of reduced wear, increased corrosion resistance, and better strength. In this study, the laser beam scan method was applied to produce an oxide dispersion strengthened (ODS) structure on a zirconium metal surface. A recrystallized Zircaloy-4 alloy sheet with a thickness of 2 mm, and Y2O3 particles of 10 μm were selected for ODS treatment using LBS. Through the LBS method, the Y2O3 particles were dispersed in the Zircaloy-4 sheet surface at a thickness of 0.4 mm, which was about 20% when compared to the initial sheet thickness. The mean size of the dispersive particles was 20 nm, and the yield strength of the ODS treated plate at 500°C was increased more than 65 % when compared to the initial state. This strength increase was caused by dispersive Y2O3 particles in the matrix and the martensite transformation of Zircaloy-4 matrix by the LBS.

Image restoration through thin turbid layers by correlation with a known object

A method to recover the image of an object behind thin turbid layers is developed by wavefront shaping technique. The optimized wavefront is generated by modulating the scattering light of a known object with a spatial light modulator. A Pearson Correlation Coefficient is introduced as a cost function for the optimization. A beam scanning method based on optical memory effect is proposed to further enlarge the Field-of-View (FOV). The experimental results show good fidelity and large FOV of the recovered image.

High-Speed Two-Photon Imaging

The small size of neuronal dendrites and spines combined with the high speed of neurophysiological signals, such as transients in membrane potential or ion concentration, necessitates that any functional study of these structures uses recording methods with both high spatial and high temporal resolutions. In this regard, conventional two-photon microscopy, in combination with fluorescent indicators sensitive to physiological parameters, has proved to be only a partial solution by providing near-diffraction-limited spatial resolution even when imaging structures deep inside light-scattering tissue. This is because the relatively slow beam-scanning methods used in most conventional two-photon microscopes severely limit the extent to which functional data can be recorded. Here, we detail developments to create high-speed two-photon imaging systems that overcome this limitation and discuss important considerations that must be taken into account when attempting to construct such systems.

Development of a Pencil Beam Scanning Method at NIRS

Development of a Pencil Beam Scanning Method at NIRS

Irradiation methods and nozzle design for the advanced proton therapy facility

A conception design of the Advanced Proton Therapy Facility (APTF) has been carried out. The system intentionally employs a slow-cycling synchrotron with a maximum energy of 250 MeV, two rotating gantries and two fixed beam nozzles for the treatment. In this paper, we try to compare the strength and weaknesses between the two treatment methods: the beam spreading and the pencil beam scanning. The application of the pencil beam scanning method and the double-scattering method together with the related nozzle design at APTF is also given. The simulation results of employing the double-scattering method have been given during the preliminary design.

The average three-dimensional target strength of fish by spheroid model for sonar surveys

Abstract Tang, Y., Nishimori, Y., and Furusawa, M. 2009. The average three-dimensional target strength of fish by spheroid model for sonar surveys. – ICES Journal of Marine Science, 66: 1176–1183. When surveying fish schools by sonar, the fish are insonified from various directions. Because the fish target strength (TS) has three-dimensional directivity, according to its orientation relative to the sonar beam, the TS must be appropriately averaged. By connecting the geometries of the sonar beam and the fish body, the relationship between the apparent orientation of fish, as viewed by the sonar, and the actual orientation in space is derived. Using this relationship, equations for calculating the three-dimensional-averaged TS (<TS>3D) are presented. A prolate-spheroid, modal-series, scattering model is then used to determine the characteristics of <TS>3D against various parameters, such as fish attitudes, fish length, sonar frequency, and method of beam scanning. The model is evaluated with two boundary conditions at the spheroid surface: a gas-fluid boundary relevant to fish with a swimbladder, and a fluid-fluid boundary relevant to fish without a swimbladder. The results reveal that <TS>3D varies greatly with the horizontal aspect (yaw angle), but only slightly with the vertical aspect (pitch angle) of the fish. The difference in <TS>3D between the side-on aspect and the end-on (head or tail) aspect increases with the ratio of the fish length to the acoustic wavelength.

Aberration Corrected Beam Scanning Stimulated Emission Depletion Microscopy

We present an aberration corrected beam scanning stimulated emission depletion (STED) microscopy. The beam scanning is essential to get images fast for practical usages in the biological applications. In this work the beam scanning method is applied to the STED microscopy. To maintain the imaging performance optimally, the aberration induced by the optic components, especially beam scanning parts, is corrected using adaptive optics. Thus, high resolution over the diffraction limit and high scanning speed are achieved without resolution and signal loss caused by the aberration.

빔 위치 관련 제어인자가 집속이온빔 패턴 증착공정에 미치는 영향

Abstract The application of focused ion beam (FIB) depends on the optimal interaction of the operation parameters between operating parameters which control beam and samples on the stage during the FIB deposition process. This deposition process was investigated systematically in C precursor gas. Under the fine beam conditions (30kV, 40㎚ beam size, etc), the effect of considered process parameters - dwell time, beam overlap, incident beam angle to tilted surface, minimum frame time and pattern size were investigated from deposition results by the design of experiment. For the process analysis, influence of the parameters on FIB-CVD process was examined with respect to dimensions and constructed shapes of single and multi- patterns. Throughout the single patterning process, optimal conditions were selected. Multi-patterning deposition were presented to show the effect of on-stage parameters. The analysis have provided the sequent beam scan method and the aspect-ratio had the most significant influence for the multi-patterning deposition in the FIB processing. The bitmapped scan method was more efficient than the one-by-one scan type method for obtaining high aspect-ratio (Width/Height > 1) patterns. 기호설명 A : 수준계AR : 폭에 대한 높이 또는 깊이 비율Lm(An) : 직교 배열 함수m : 실험의 크기 n : 배치 가능한 최대 인자수

Actuator Mechanism Using Suspension-wire for 2D Scanning

Laser beam scanning technology has been used in various machinery such as laser beam printers, laser processing machines. Recently, the usage such as distance sensors for automobiles, area sensors for robots has expanded further. According to it, the miniaturization of beam scanning equipment, advanced features, and low-pricing have also come to be called for strongly. We suggest a method of two-dimensional beam scanning by driving a lens with an electromagnetic actuator. We use suspension wires to hold the scan lens. As a result, two-dimensional beam scanning is possible by simple structure. This paper describes the structure of the scanner module system and characteristics of the prototype model.

Beam Scanning Confocal Differential Heterodyne Interferometry

This article presents a new approach to the design of confocal differential heterodyne interferometer (CDHI), which is a combination of differential heterodyne interferometer (DHI) with confocal laser scanning microscopy (CLSM). The CDHI can measure a step height over a quarter of wavelength of the light source, which can not be accurately measured by DHI and CLSM, respectively. The approach is that it utilizes a beam-scanning method instead of transporting a sample to be measured. The measurement results carried out for samples having step height are found to be comparable in precision with those measured by commercial scanning electron microscopes.

Specifying Carbon Ion Doses for Radiotherapy: The Heidelberg Approach

There are currently no guidelines for prescribing and reporting radiation therapy (RT) with ion beams. In this paper an overview over some technical aspects and their implication on ion RT are reported. This includes a discussion of the difference in the treatment planning systems currently used for active and passive beam shaping systems, aspects of patient positioning and target definition and dose prescription. Special emphasis is put on the questions arising from the use of the beam scanning methods in combination with biological treatment plan optimization, which is used in the German heavy ion therapy facility at GSI and will also be introduced at the hospital based facility in Heidelberg. Furthermore, the Heidelberg approach for the clinical dose prescription is compared with the methods developed at HIMAC in Chiba, Japan.

Wide-range, high-resolution optical steering device

High-resolution, large-angle optical beam scanning methods are sought to meet the ever-increasing demands of free-space laser communication, medical imaging and treatment, printers, scanners, and laser radar. We present a precise steering method with high angular resolution and a wide scanning range. The proposed beam-steering device is also lightweight and compact, which are significant advantages in many applications. The scanning is implemented by means of a pair of diffraction gratings, which can be translated relative to one another, and a tunable-wavelength laser. Thus the beam is steered by the combined effect of two independent mechanisms. The agility of wavelength tuning enhances the performance of a grating-based device, while the sensitivity to chromatic aberrations is minimized by performing the coarse steering with the diffraction grating. The system performance is demonstrated experimentally, and the results are reported. To the best knowledge of the authors, We present for the first time a scanning system that includes a combination of a pair of diffraction gratings and a tunable-wavelength laser.

Scanning-beam digital x-ray (SBDX) technology for interventional and diagnostic cardiac angiography

The scanning-beam digital x-ray (SBDX) system is designed for x-ray dose reduction in cardiac angiographic applications. Scatter reduction, efficient detection of primary x-rays, and an inverse beam geometry are the main components of the entrance dose reduction strategy. This paper reports the construction of an SBDX prototype, image reconstruction techniques, and measurements of spatial resolution and x-ray output. The x-ray source has a focal spot that is electronically scanned across a large-area transmission target. A multihole collimator beyond the target defines a series of x-ray beams directed at a distant small-area detector array. The prototype has a 23 cm X 23 cm target, 100 X 100 focal spot positions, and a 5 cm X 5 cm CdTe detector positioned 150 cm from the target. With this nonmechanical method of beam scanning, patient images with low detected scatter are generated at up to 30 frame/s. SBDX data acquisition is tomosynthetic. The prototype simultaneously reconstructs 16 planes spaced throughout the cardiac volume using shift-and-add backprojection. Image frames analogous to conventional projection images are generated with a multiplane compositing algorithm. Single-plane versus multiplane reconstruction of contrast-filled coronary arteries is demonstrated with images of the porcine heart. Phantom and porcine imaging studies show multiplane reconstruction is practicable under clinically realistic levels of patient attenuation and cardiac motion. The modulation transfer function for an in-plane slit at mechanical isocenter measured 0.41-0.56 at 1 cycle/mm, depending on the detector element to image pixel interpolation technique. Modeling indicates that desired gains in spatial resolution are achievable by halving the detector element width. The x-ray exposure rate 15 cm below isocenter, without table or patient in the beam, measured 11.5 R/min at 120 kVp, 24.3 kWp and 3.42 R/min at 70 kVp, 14.2 kWp.

A study on multibeam pulse chasing for bistatic radar

AbstractTo improve the volume search efficiency of a bistatic radar with the transmitting antenna and the receiving antenna positioned apart, a known beam scanning method is pulse chasing that scans the receive beam at high speed in response to the propagation of the transmitted pulses. However, in normal pulse chasing, the receive beam width cannot be narrower than some value in order to receive all of the transmitted pulses without losses. In other words, a limit is the antenna gain cannot be increased. The problem is the receive signal‐to‐noise ratio (SNR) decreases compared to when pulse chasing is not performed. In this paper, we propose multibeam pulse chasing, a beam scanning technique using multiple receive beams based on digital beam forming, as the solution. We show that even if the transmitted pulse width is relatively long, if the number of multibeams is increased, the received SNR does not exhibit a decrease. Furthermore, we study a method to decrease the number of multibeams by dropping a portion of the receive pulses when pulse compression is applied as the transmission and reception methods, and present the computational result of the relationship between the number of multibeams and the received SNR when the Taylor window is applied. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(1): 11–21, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20240

Optimization of the Chemical Vapor Deposition Induced Focused Ion Beam

This paper carried out some experimentation and verification of the chemical vapor deposition induced ion beam and sputtering using the SMI8800 manufactured by SEIKO. FIB-CVD is very useful tools to repair the mask or IC with sub-micrometer precision. However it need to be much studied in some fields such as FIB-CVD mechanism and the characteristics of pattern accuracy and yield of CVD according to many parameters related to ion beam, beam scanning methods and type of specimen etc. Therefore the verification on FIB-CVD characteristic such as accuracy and yield according to scanning area and scanning time is carried out in this study. And it suggests the optimization parameters, various mechanisms of the chemical vapor deposition induced ion beam and sputtering effect for simple pattern.

Structure of Dental Resin-Based Adhesive Materials

This study aimed to show that the polymerization contraction of dental light cured resin-based materials, when it was used as adhesives on hard substrate, produces voids at the material/substrate interface. Two liner/base systems, one glass-ionomer, one restorative composite resins and two compomers were cured using mirror-like glass slide as a compliance-free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam scanning method. Nanoperiodic structure of 3D images, section analysis and roughness characteristics (Ra and Rz)) indicated that polymerization contraction produced voids at the interface. In visible light-cured (VLC) materials, the interface porosity decreased when an irradiation pause was carried out during gelation.