Magnification Ratio Research Articles

INFLUENCE OF DIFFERENT SPECIFICATION OF MUD WALL ON STRUCTURE PERFORMANCE USING EXPERIMENTAL INVESTIGATION

The wall strength magnification ratio of mud wall of the defined specification was revised by the Ministry of Land, Infrastructure and Transport notification No. 1543 in 2004. The used material and the manufacture method for mud wall change with areas. While manufacture method and used material differ, the specifications of mud wall differ, which causes structure performance differ. In this paper, the various lathwork of mud wall and materials from mud of wall which are performed in various areas have been investigated. Based on investigated results the experimental variable of the lathwork of mud wall and use material have been determined. In order to predict the shear behavior of the mud wall in various manufacture states, tests on 129 different types of partial wall have been carried out.

Advantages of magnification in digital phase-contrast mammography using a practical X-ray tube

Phase-contrast imaging with a practical cone-beam X-ray tube has been realized for clinical use in digital mammography using computed radiography (CR). To perform phase-contrast imaging, the X-ray detector must be distanced from an object so that the phase-contrast image achieves magnification; in a mammography unit dedicated to phase-contrast imaging, the magnification ratio is 1.75. When using an X-ray tube with a 0.1-mm focal spot, it appears that the penumbra in magnification blurs both projected images and the phase contrast, which generates an edge effect. However, where the sampling pitch of the CR plate is 43.75 μm, the blur stretches the width of the phase contrast so that unit pixels in the detector can capture it. Note that the width of an ideal phase contrast using an X-ray point source results in a phase contrast too narrow for detection with CR. In addition to phase contrast improving image quality, a re-scaling effect increases image sharpness in magnification. Further, image noise induced by magnification can be reduced during printing to photothermographic dry film by demagnifying the digital output image to the original image size. After demagnification by 1/1.75 from 43.75 μm in image acquisition, a 25-μm pixel size of the output image is obtained so that the spatial resolution matches that of conventional screen-film mammography. In this paper, such technical advantages of magnification in digital phase-contrast mammography are reviewed, and the image quality of phase-contrast images is discussed in light of diagnostic requirements in detecting breast cancer.

50.4: High Resolution Autostereoscopic 3D Display with Proximity Projector Array

AbstractA 3D architecture which exploits proximity projector array to project tiled image of low magnification ratio from microdisplays has been proposed as a solution for large screen and high resolution spatial multiplex autostereoscopic display. with descent lenticular and projection optics design associated with dedicated pixel mask, the proposed 3D configuration shows low crosstalk between viewing zones and demonstrates a potential alternative to increase pixel count for wide view and high resolution 3D displays.

Modeling of lateral magnification changes due to changes in corneal shape or refraction

Background and Purpose Especially after corneal surgery the lateral magnification of the eye providing the retinal image size of an object is a crucial factor influencing visual acuity and binocularity. The purpose of this study is to describe a paraxial computing scheme calculating lateral magnification changes (ratio of the image sizes before and after surgery) due to variation in corneal shape and spectacle refraction. Calculation strategy From the 4 × 4 refraction and translation matrices the system matrix representing the entire ‘optical system eye’ and the pupil matrix describing the sub-system from the spectacle correction to the aperture stop were defined for the state before and after surgery. As the chief ray is assumed to pass through the centre of the aperture stop, the 2 × 2 matrix of the lateral magnification ratio from preoperative to postoperative is described by the 2 × 2 sub-matrices of the respective pupil matrices. The cardinal meridians can be extracted by calculating the eigenvalues and eigenvectors. Working example Vertex distance 14 mm, measured distance between corneal apex and aperture stop 3.6 mm, keratometry 39 D + 6 D/0° to 47 D + 3 D/30° and refraction 3.5 D − 5 − 5 D/5° to −4.0 D − 3.5 D/25° preoperatively to postoperatively. The matrix of magnification ratio from preop to postop yields (0.8960 −0.0085;0.0074 0.9371) and the eigenvalues decomposition provided a 10.7% minified image at 170.1° and a minified image of 6.1% at 78.7°, which both are clinically relevant. Conclusion We presented a straight-forward computer-based strategy for calculation of retinal image size changes using 4 × 4 matrix notation. With this model the meridional changes in lateral magnification from the preoperative to the postoperative stage or between follow-up stages can be estimated from keratometry, refraction, vertex distance and anterior chamber depth, which might be important for binocularity and vision tests in corneal surgery.

Optimal design of a flexure-hinge precision stage with a lever

Lever mechanisms are usually used to enlarge output displacements in precision stages. A precision stage employing a lever mechanism and flexure hinges is analyzed theoretically, with bending in the lever considered. Relations between design parameters and magnification ratio, and the optimal values for the parameters to achieve a longer stage displacement are presented. Finite element analysis is used to verify the theoretical analysis. It is found that adjustment of lever dimensions and hinge stiffnesses can increase the stage travel range significantly.

Magnification Ratios and Working Distances of “Head and Attachment Magnifiers” Made by Eschenbach

Purpose: Because magnification ratios (MRs) indicated (IMRs) in catalogues of “Head and Attachment Magnifiers” made by Eschenbach are not common values, we examined the IMRs in relation to the working distances (WDs) indicated (IWDs) in the catalogues and then calculated the corrected WDs. Methods: From information about loupes given in the catalogues and measurements made with a lensometer, we determined (1) the power of each magnifier and (2) the accommodation needed; we then (3) calculated the MR and (4) established the corrected WD. Results: When used within the IWD, monocular loupe had an MR that was the same as the IMR. However, for binocular loupes, the MR was lower than the IMR. When the loupes were used at the revised WD recommended by the engineer of Eschenbach, binocular loupes had an IMR of “–1,” meaning that a WD shorter than the revised WD was needed to attain the IMR. Conclusion: With Eschenbach head and attachment magnifiers, the IMR is only attained when viewed at a shorter WD than that i...

Three-dimensional measurement endoscope system with virtual rulers

Conventional endoscopic images do not provide quantitative 3-D information. We present an endoscope system that can measure the size and position of an object in real time. Our endoscope contains four laser beam sources and a camera. The procedural steps for 3-D measurements are as follows. First, to obtain the function that maps 2-D coordinates of an image point to its 3-D coordinates in 3-D space, we observe a standard chart with the endoscope lens and determine the correspondence between the image and object height. In addition to the mapping, this function can correct barrel-shaped distortion of endoscopic images. The system detects laser spots on an object surface automatically using a template matching method, and maps the 2-D coordinates of the laser spots to the 3-D coordinates by the triangulation method. Then the system calculates the magnification ratio on the object plane, which is perpendicular to the optical axis and passes the laser spot, so that the system can superimpose a ruler whose scale fits the 3-D coordinates of the object. Thus, physicians can measure the size and position of objects in real time on undistorted images similar to placing rulers on the surface of an organ.

Gravitational Lensing Model Degeneracies: Is Steepness All‐Important?

In gravitational lensing, steeper mass profiles generically produce longer time delays but smaller magnifications, without necessarily changing the image positions or magnification ratios between different images. This is well known. We find in this paper, however, that even if steepness is fixed, time delays can still have significant model dependence, which we attribute to shape modeling degeneracies. This conclusion follows from numerical experiments with models of 35 galaxy lenses. We suggest that varying and twisting ellipticities, features that are explored by pixelated lens models but not so far by parametric models, have an important effect on time delays.

A magnification device for precision mechanisms featuring piezoactuators and flexure hinges: Design and experimental validation

This work presents an experimentally-validated approach for designing a precision magnification mechanism featuring flexure hinges and piezoelectric actuators . The governing equations of motion are derived using Lagrange’s equation and a two-step amplification mechanism is optimally designed and fabricated. Subsequently the analytical model is verified experimentally by comparing the simulated magnification ratio with experimental data. The device is then integrated with a piezostack actuator, and subsequently tracking control responses for step and sinusoidal trajectories are empirically evaluated in the time domain. Finally, an animation code is developed for the mechanism and some snapshots are presented.

A family of quasi-cubic blended splines and applications

A class of quasi-cubic B-spline base functions by trigonometric polynomials are established which inherit properties similar to those of cubic B-spline bases. The corresponding curves with a shape parameter a, defined by the introduced base functions, include the B-spline curves and can approximate the B-spline curves from both sides. The curves can be adjusted easily by using the shape parameter a, where dpi(a,t) is linear with respect to da for the fixed t. With the shape parameter chosen properly, the defined curves can be used to precisely represent straight line segments, parabola segments, circular arcs and some transcendental curves, and the corresponding tensor product surfaces can also represent spherical surfaces, cylindrical surfaces and some transcendental surfaces exactly. By abandoning positive property, this paper proposes a new C2 continuous blended interpolation spline based on piecewise trigonometric polynomials associated with a sequence of local parameters. Illustration showed that the curves and surfaces constructed by the blended spline can be adjusted easily and freely. The blended interpolation spline curves can be shape-preserving with proper local parameters since these local parameters can be considered to be the magnification ratio to the length of tangent vectors at the interpolating points. The idea is extended to produce blended spline surfaces.

Geometrical analysis of puppet-theater and cardboard effects in stereoscopic HDTV images

A fundamental element of stereoscopic image production is to geometrically analyze the conversion from real space to stereoscopic images by binocular parallax under various shooting and viewing conditions. This paper reports on this analysis, particularly on the setting of the optical axes of three-dimensional (3-D) cameras, which has received little attention in the past. First, we identified the conditions for setting the optical axes that maintain linearity during the conversion from real space to stereoscopic images. We then clarified, in geometrical terms, the shooting and viewing conditions and also conditions under which the puppet-theater effect and cardboard effect occur. The results showed that the parallel camera configuration, by which optical axes are kept parallel to each other, does not produce the puppet-theater effect as the apparent magnification (lateral magnification) of a shooting target is not dependent on the shooting distance. However, the toed-in camera configuration, where the apparent magnification of a shooting target is dependent on the shooting distance, may produce this effect. The cardboard effect is shown to be likely to occur for both camera configurations by defining this phenomenon by the ratio of depthwise reproduction magnification (depth magnification) and apparent reproduction magnification (lateral magnification). Lastly, the paper reports on the relationship between the results of this analysis and those of subjective evaluation experiments. The results need a closer examination by using many more images.

Simulations of strong gravitational lensing with substructure

Galactic-sized gravitational lenses are simulated by combining a cosmological N-body simulation and models for the baryonic component of the galaxy. The lens caustics, critical curves, image locations and magnification ratios are calculated by ray shooting on an adaptive grid. When the source is near a cusp in a smooth lens' caustic, the sum of the magnifications of the three closest images should be close to zero. It is found that in the observed cases this sum is generally too large to be consistent with the simulations, implying that there is not enough substructure in the simulations. This suggests that other factors play an important role. These may include limited numerical resolution, lensing by structure outside the halo, selection bias and the possibility that a randomly selected galaxy halo may be more irregular, for example, due to recent mergers, than the isolated halo used in this study. It is also shown that, with the level of substructure computed from the N-body simulations, the image magnifications of the Einstein cross-type lenses are very weak functions of source size up to 1 kpc. This is also true for the magnification ratios of widely separated images in the fold and cusp-caustic lenses. This means that selected magnification ratios for the different emission regions of a lensed quasar should agree with each other, barring microlensing by stars. The source size dependence of the magnification ratio between the closest pair of images is more sensitive to substructure.

Response of a Cylindrical Premixed Flame to Periodic Concentration Fluctuation

The response of a cylindrical premixed flame to periodic concentration fluctuation was investigated. The flame was formed in a porous cylinder by percolating a lean methane-air mixture uniformly through the cylinder wall. The burner used here was devised so as to cause fluctuations of the mixture concentration (equivalence ratio) only in the radial direction of the flow (vertically to the cylindrical flame surface) without varying the flow field. Using this burner, the time variations of burning velocity, burnt gas temperature and flame luminosity were measured for the mixture in a range of fluctuation frequencies from 3 to 50Hz, and the results were examined from the viewpoint of flame curvature effects. The results show that the variation width of the burning velocity of the dynamic flame is larger than that of the static flame in the concentration range corresponding to the fluctuation. Burnt gas temperature and flame luminosity also exhibit similar tendencies. The magnification ratio of the variation width depends on the flame curvature, and a large flame curvature results in a sustainable flame, even for a mixture leaner than the flammability limit of the static flame.

The evolution of substructure in galaxy, group and cluster haloes — III. Comparison with simulations

In a previous paper, we described a new method for including detailed information about substructure in semi-analytic models of halo formation based on merger trees. In this paper, we compare the predictions of our model with results from self-consistent numerical simulations. We find that in general the two methods agree extremely well, particularly once numerical effects and selection effects in the choice of haloes are taken into account. As expected from the original analyses of the simulations, we see some evidence for artificial overmerging in the innermost regions of the simulated haloes, either because substructure is being disrupted artificially or because the group-finding algorithms used to identify substructure are not detecting all the bound clumps in the highest-density regions. Our analytic results suggest that greater mass and force resolution may be required before numerical overmerging becomes negligible in all current applications. We discuss the implications of this result for observational and experimental tests of halo substructure, such as the analysis of discrepant magnification ratios in strongly lensed systems, terrestrial experiments to detect dark matter particles directly or indirect detection experiments searching for positrons, gamma-rays, neutrinos or other dark matter decay or annihilation products.

Posterior corneal surface changes after hyperopic laser in situ keratomileusis

To evaluate posterior corneal surface topographic changes after hyperopic laser in situ keratomileusis (H-LASIK) using Orbscan I (Orbtek, Inc.). Department of Ophthalmology, Nara Medical University, Nara, Japan. In 25 eyes of 15 patients who had H-LASIK, the posterior corneal surface was measured with slit-scanning corneal topography (Orbscan I) preoperatively and 1 year postoperatively. The center as a fit zone and calculated posterior corneal surface changes were taken at 4 points: nasal, temporal, superior, and inferior sides in the 5.0 mm diameter. The posterior corneal topographic changes were analyzed using an analysis of variance. The postoperative:preoperative magnification ratio of the posterior corneal surface was calculated in a theoretical eye model. When a "+" reading was defined as the forward displacement and "-" was defined as the backward displacement, the mean posterior corneal topographic changes were -2.8 microm +/- 27.9 (SD) at the nasal side, -4.5 +/- 27.8 microm at the temporal side, -3.9 +/- 20.1 microm at the superior side, and -2.3 +/- 20.1 microm at the inferior side. The posterior corneal surface between any 2 examined points showed no significant difference after H-LASIK. In addition, the hypothetical change in the posterior cornea was -8.3 microm after +3.0 diopter H-LASIK, which was approximately closer to the study results. In each side, the amount of the attempted correction was significantly correlated with the posterior corneal topographic change. Clinical measurement of the posterior corneal displacement after H-LASIK with Orbscan revealed a backward shift. This change corresponded to the hypothetical artifactual changes with Orbscan; that is, changes in the magnification ratio.

Underestimation of corneal thickness by Orbscan after myopic correction

In the reply1 to a letter about the article on corneal thickness measured by Orscan (Bausch & Lomb),2 Miyata could not satisfactorily explain why the corneal thickness was underestimated after myopic LASIK. In the article, Miyata et al. speculated that the reasons were changes in the refractive index, stromal haze, changes in the anterior contour of the cornea, and inappropriate reconstruction algorithms that might occur after LASIK. We propose another explanation of the underestimation of corneal thickness measured by Orbscan after myopic LASIK. The posterior surface of the cornea is observed through a lens composed of the overlying epithelium and stroma. The lens changes its shape and thickness after myopic LASIK. Then, the posterior surface of the cornea observed through the lens becomes relatively smaller than that observed before the surgery. We have described a method to calculate the change in the magnification ratio of the posterior cornea after myopic LASIK under the paraxial assumption.3 If the preoperative and postoperative corneal thicknesses are 600 μm and 480 μm, respectively, the corneal refractive index is 1.376, and the amount of myopic correction is 10.0 diopters, the image of the posterior cornea will become smaller by approximately 0.8%.4 If the posterior radius of curvature of the cornea is 6.2 mm, ie, 6200 μm, it will become smaller by 50 μm. Details of the calculation algorithm of the Orbscan have not been released by the manufacturer. If the apparent change in the posterior cornea is directly translated to the apparent decrease in the corneal thickness, the cornea will become thinner by 50 μm. Figure 1 shows the relationship between the amount of myopic correction and the actual and hypothetically calculated apparent corneal thickness. It looks very similar to Figure 3 in the article.2Figure 1.: The relationship between the amount of myopic correction and the actual and hypothetically underestimated corneal thickness. The greater the amount of myopia corrected, the greater the underestimation of the corneal thickness.The change in the magnification ratio of the posterior cornea could be related to the apparent forward shift of the posterior cornea displayed with Orbscan after myopic correction.4 I hope this hypothesis will help explain many of the discrepancies in the data obtained by Orbscan after keratorefractive surgery. Shinji Maruoka MD Yoshiaki Nawa MD Kozo Masuda ORT Tetsuo Ueda MD Yoshiaki Hara MD Hiroshi Uozato PhD Nara, Japan

Correction of a coherent image during KrF excimer laser ablation using a mask projection

Using masks for laser ablation has proven useful in the fabrication of prototypes for the manufacturing of micro-fluidic devices. In this work, an excimer laser was used to engrave microscopic channels on the surface of polyethylene terephthalate (PET), which showed a high absorption ratio for an excimer laser beam with a wavelength of 248 nm. When 50 μm wide rectangular microscopic channels were made using a 500×500 μm square mask and a magnification ratio of 1/10, ditch-shaped defects were found at both corners. The calculation of the laser beam intensity showed that a coherent image in the PET specimen caused the defects. An analysis based on the Fourier diffraction theory enabled the prediction of a coherent shape at the image plane, as well as a diffracted beam between the mask and the image plane. The analysis also showed that the diameter of the aperture was a predominant factor toward the elimination of ditch-shaped defects in the rectangular microscopic channels on the PET produced by an excimer laser ablation.

Accuracy of Measurements on Digital Videostroboscopic Images of the Vocal Folds

The reliability of objective measurements on digital laryngeal images was investigated. The magnitude of the error of measurement of surface areas by visually tracing the outline was determined for three different areas: the area of the lesion and, during vibration, the glottal area on maximal opening of the vocal folds and the glottal area on maximal closing of the vocal folds. The errors in these areas were 10% to 30%. The results suggest that the error is mainly due to the uncertainty of the real outline of areas with a vague boundary. Correction for differences in magnification between two images (posttherapy and pretherapy) is of importance in about 25% to 65% of cases, depending on the area measured. Only when the magnification ratio is small (less than about +/- 10% from 1.0) may a correction not be necessary.

Evaluation of apparent ectasia of the posterior surface of the cornea after keratorefractive surgery

To calculate the apparent posterior corneal changes after keratorefractive surgery and reevaluate corneal ectasia displayed by Orbscan (Orbtek). Department of Ophthalmology, Nara Medical University, Nara, Japan. Postoperative:preoperative magnification ratio of the posterior surface of the cornea was calculated in a theoretical eye model. Assuming the preoperative corneal thickness is 600.00 microm, the preoperative refractive power of the anterior corneal surface is 48.0 diopters (D), the refractive power of the cornea is 1.376, the ablation diameter is 6.0 mm, the postoperative corneal thickness is 480.00 microm, the postoperative refractive power of the anterior corneal surface is 38.0 D, and the posterior surface of the cornea does not change postoperatively, the apparent image of the posterior surface of the cornea becomes 0.778% smaller postoperatively. If the posterior radius of curvature of the cornea is 6.2 mm, it becomes smaller by 48.24 microm. If this change directly affects the difference map, the posterior surface of the cornea moves forward by 48.24 microm. The results correspond to the amount of ectasia in previous reports. This artifact may explain the apparent ectasia detected by Orbscan.

NewVRMagnification Ratios of QSO 0957+561

We present VR magnification ratios of QSO 0957+561 that are inferred from the GLITP light curves of Q0957+561A and new frames taken with the 2.56 m Nordic Optical Telescope about 14 months after the GLITP monitoring. To extract the fluxes of the two close components, two different photometric techniques are used, pho2comC and psfphot. From the two photometric approaches and a reasonable range for the time delay in the system (415-430 days), we do not obtain achromatic optical continuum ratios, but ratios depending on the wavelength. Our final global measurements ΔmAB(λV) = 0.077 ± 0.023 mag and ΔmAB(λR) = 0.022 ± 0.013 mag (1 σ intervals) are in agreement with the Oslo group results (using the same telescope in the same seasons but another photometric task and only one time delay of about 416 days). These new measurements are consistent with differential extinction in the lens galaxy, the Lyman limit system, the damped Lyα system, or the host galaxy of the QSO. The possible values for the differential extinction and the ratio of total to selective extinction in the V band are reasonable. Moreover, crude probability arguments suggest that the ray paths of the two components cross a similar dusty environment, including a network of compact dust clouds and compact dust voids. As an alternative (in fact, the usual interpretation of the old ratios), we also try to explain the new ratios as being caused by gravitational microlensing in the deflector. From magnification maps for each of the gravitationally lensed images, using different fractions of the surface mass density represented by the microlenses as well as different sizes and profiles of the V-band and R-band sources, several synthetic distributions of [ΔmAB(λV), ΔmAB(λR)] pairs are derived. In some gravitational scenarios, there is an apparent disagreement between the observed pair of ratios and the simulated distributions. However, several microlensing pictures work well. To decide between either extinction, microlensing, or a mixed scenario (extinction + microlensing), new observational and interpretation efforts are required.