Literatura académica sobre el tema "Optical-mechanical analogy"

Abstract The continuum-mechanical formulation of wave mechanics suggests that there is an intermediate stage of theoretical generality between wave mechanics and point mechanics, namely, continuum mechanics. When that argument is applied to the corresponding transition from wave optics to geometrical optics, the corresponding intermediate stage is essentially the geometrical theory of diffraction, i.e., the theory of diffracted geodesics.

The methods devised by Gustav Mie in 1908 to explain the scattering of electromagnetic waves have a close analogy with quantum-mechanical models developed many years later to describe nuclear scattering. In particular, these models use either a complex index of refraction or a complex nuclear scattering potential to account for attenuation caused by non-elastic scattering. We briefly outline the historical development of these models and give examples illustrating the close analogy between them, their parameters, and the resulting scattering. In both models, the ratio of the incident wavelength to the object size, λ/D, can be determined from the scattering characteristics, allowing the extraction of microscopic particle dimensions. This close analogy allows students to simulate accelerator-based nuclear scattering experiments with table-top optical-scattering experiments.

Au-Yeung, Kin Chung = 以光學模擬量子自旋和機械鐘擺的相互作用 / 歐陽健聰.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 80-81).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.
Au-Yeung, Kin Chung = Yi guang xue mo ni liang zi zi xuan he ji xie zhong bai de xiang hu zuo yong / Ouyang Jiancong.

This chapter provides a new intellectual context for John Milton’s treatment of light and vision in Paradise Lost (1667) by locating Milton’s poem within the framework of seventeenth-century optical theory. It does so by examining the parallels and distinctions between the role played by light in Milton’s model of vision and models proposed by Johannes Kepler and René Descartes. The main argument of the chapter is that Milton adopts Kepler’s theory of the retinal image, which posits that the human eye operates according to the mechanical principles of a camera obscura. But where Kepler and Descartes use the analogy of the camera obscura to explain the properties of light as it relates to vision, Milton uses it to express the fragility of vision within this new model. Speaking from a position of blindness, Milton’s narrator explores the theological and epistemological implications of having light at ‘one entrance quite shut out’, thereby being ‘presented with a Universal blanc’ (PL 3.48–50) in the place of the retinal projection screen.

Abstract The fundamental dual nature of neutrons –sometimes a particle (when detected) and sometimes a wave (when traversing the interferometer) – is wonderfully mani-fested by the non-local nature of the neutron interferometry experiments discussed in this chapter. We begin with a discussion of the series of experiments, called gravitationally induced quantum interference, in Section 7.1. Then in Section 7.2, the effect of the Earth’s rotation on the phase of a neutron de Broglie wave is described. This is the quantum mechanical analogue of the Michelson et al. (1925) experiment with light. An experiment in which this Sagnac phase shift was observed due to rotation of the interferometer on a turntable phase within the laboratory frame is also discussed (Atwood et al. 1984). An experiment related to the small effective mass of the neutron propagating in a crystal under Bragg reflecting conditions and its deflection due to the Coriolis force is discussed in Section 7.2.3 (Raum et al. 1997). Acceleration-induced interference, which is related to the gravity experiments by the principle of equivalence, is discussed in Section 7.3 (Bonse and Wroblewski 1983). Phase shifts caused by the motion of matter within the interferometer are related to the optical Fizeau effect. Several neutron Fizeau-type experiments are discussed in Section 7.4.

Many quantum optical systems exhibit first-order phase transition analogy.1 Fluctuations of the optical field in such systems are due to spontaneous emission noise. The nature of these fluctuations for various systems has been discussed using various approaches. Fully quantum mechanical and Langevin equation treatments have been given for the dye laser2,3 and the laser with a saturable absorber (LSA) with homogeneously broadened media.2,4 For inhomogeneously broadened media, such treatments are either valid for low intensities or do not fully take into account the effect of quantum noise.5 In this contribution we present a fully quantum mechanical treatment for the LSA with an inhomogeneously broadened absorber using the Foch state representation of the density matrix.2,6

The effect of the shape and distribution of perforations in parallel plate capacitive MEMS devices on squeeze-film damping is presented. The squeeze film effect is the most important damping effect on the dynamic behavior of most MEMS devices that employ capacitive sensing and actuation, which typically employ narrow air gaps between planar moving surfaces [1, 2]. The stationary plate of a capacitive device is often perforated to reduce the damping and sensor noise and improve the frequency response. The formula for determining the total viscous damping in the gap contains a coefficient Cp that is associated with the geometry and distribution of the holes on the stationary plate. In this study, the coefficient Cp is determined using the finite element method using ANSYS by analogy with heat conduction in a solid with internal heat generation. Round, elliptical, rectangular, and oval holes that are distributed either aligned or offset are analyzed and compared. It is shown that the surface fraction occupied by the perforations is not the only factor that determines Cp. Both the shape and distribution strongly affect the damping coefficient [3, 4]. By using elongated perforations that are properly distributed, the squeeze film damping could be minimized with the minimum amount of perforation. The analysis performed in this work is quite general being applicable to a very large spectrum of frequencies and to various fluids in capacitive sensors. These results can facilitate the design of mechanical structures that utilize capacitive sensing and actuation, such as accelerometers, optical switches, micro-torsion mirrors, resonators, microphones, etc.

We have developed and demonstrated a technique for optical excitation of mechanical resonance that does not require coherent, monochromatic, or time-varying light. Previous methods for optically exciting mechanical motion in microscale devices required monochromatic, coherent light or time varying light. This technology could allow sunlight (or other ambient light source) to drive a MEMS device. It could also be used to convert sunlight to mechanical energy and subsequently to electrical energy through piezoelectric or capacitive techniques, essentially a micromechanical analog to the photovoltaic cell. We have demonstrated this method of optical excitation of a MEMS cantilever using simple cantilever beam structures fabricated using Sandia National Laboratories’ SUMMiT V™ process. The bimorph structure was created with polysilicon and aluminum. The minimum power to induce resonance was 3.5–4 mW of optical power incident on the cantilever under a vacuum of less than 1 mTorr. Resonance was observed at 45.6 kHz (slightly less than the 48.5 kHz predicted by FEA).

This paper presents opto-electro-mechanical mixed-signal system-level modeling of micro deformable mirror, the core component of micro adaptive optics system. Micro deformable mirror element was decomposed into functional components and those components were connected to establish a network to represent the real device. Many mirror element models were put together to represent mirror arrays. Then simulations were implemented in just one emulator. The mirror element was decomposed into three kinds of functional components based on this method, i.e. mechanical structure component (beam and mass), electro-mechanical coupling component (electrostatic gap) and optics component (reflective mirror). The mechanical structure behavioral model, the electro-mechanical coupling behavioral model and optical behavioral model could be set up based on the theory of rigid body relative movement and matrix structural analysis, the law of energy conservation and the theory of ray optics and Gaussian beam, respectively. The models were coded in analog hardware description language and a system-level model of micro deformable mirror was established using these models. Electro-mechanical coupling simulations were implemented to find the resonance frequency, the response time and voltage-displacement relationship of the micro deformable mirror element. The frequency analysis results were compared with ANSYS simulations, and the result proved that the method has near FEM accuracy. Then optical phase modulation simulation of micro deformable mirror arrays was implemented to investigate the relationship between input optical signal and output optical signal when control voltage was applied. The simulation result indicated that the mixed-signal system-level simulation of micro deformable mirror could be accomplished rapidly in this way.

This study focuses on the fundamental of solidification of commercial grey cast iron as a function of the externally applied cooling rate. Grey cast iron powders were prepared using the drop-tube method, which is a good analogue for commercial production via high pressure gas atomization. The as-solidified droplets were collected and sieved into size ranges from > 850 μm to < 53 μm diameter, with estimated cooling rates of 500 K s−1 to 75,000 K s−1, with each sieve fraction being prepared for metallographic characterization. The microstructure and phase composition of the powders were analyzed using XRD, optical and scanning electron microscopy, with the results being compared against a control sample subject to slow cooling in the drop-tube crucible; which has typical grey cast iron microstructure with extensive flake graphite in a largely ferrite matrix. In contrast, flake graphite was absent in virtually all the drop-tube samples, even in those with the most modest cooling rates. Microstructural analysis revealed that as the cooling rate increased there was less fragmentation of the primary austenite/ferrite dendrites and the volume fraction of primary dendritic material increased. Hence, as the particle fractions get smaller (D < 106 μm) there is a distinct microstructural evidence of a martensite phase which is related to its better mechanical properties (microhardness) as the sample sizes decrease.

During the last decades, the so-called two-fluid model has been the most widely used in two-phase flow studies for environmental and industrial applications. In this model, one set of mass, momentum and energy balance equations is written for each phase, therefore the model is able to deal with mechanical and thermal imbalances. The two phases cannot evolve independently, since they are coupled together through interfacial interaction terms representing the average exchanges between the two phases. The success of the two-fluid model in particular situations strongly depends on the modeling of these interfacial interaction terms. The interfacial interaction terms generally involve the volumetric interfacial area, that is the contact area between phases per unit volume of the two-phase mixture. This interfacial area is very important to express correctly the interfacial exchanges of mass, momentum and energy, and also gives an additional information about the interfaces structure, hence on the flow regime (bubbly, droplet, flow with separated phases…). Therefore, considerable attention has been focused on this subject in the last ten years. Theoretical and experimental researches have been done, especially on the bubbly flow configuration. Despite all these efforts, some issues remain and a general model giving the volumetric interfacial area in all two-phase flow regimes is not yet available. In the subject of the interfacial area modeling, three types of issues remain : theoretical, experimental and numerical ones. In what follows, we examine these three points independently in the general context of all two-phase flow regimes. From the theoretical point of view, most of the authors working on the subject try to write a seventh balance equation for the volumetric interfacial area, in addition to the six balance equations of the two-fluid model. This method seems promising, since it is able to deal with complex situations where different phenomena responsible for the flow regimes transitions, like coalescence, break-up, phase change and so on, act together. The transport of the VIA by the flow is also taken into account in this equation. However, such an equation is very difficult to establish in the general case where the flow regime is not known a priori. One should distinguish the relatively simple case of dispersed two-phase flows (bubbly and droplet flows) from the other, more complex, cases like the stratified flow, the annular flow or the churn-turbulent flow. For the dispersed flow case, an analogy with the kinetic theory of gases is generally adopted. The bubbles or droplets are described by a probability density function, as for the molecules in the kinetic theory of gases. A Liouville type equation is written for the pdf and the VIA balance equation is deduced from this equation. This method is very advantageous for the dispersed flow case since the coalescence and break-up terms can be introduced in a natural way. These terms correspond to the collisions terms in the kinetic theory of gases. The transport velocity appearing in the VIA balance equation is also clearly defined in this approach : it corresponds to the centre of area velocity of the particles swarm. Unfortunately, this method cannot be easily extended to the other flow regimes, especially the flows with separated phases like the annular or the stratified flows. To make the analogy with the kinetic theory of gases, one needs to introduce a population balance, and there is no population in the stratified or the annular flows, since only one continuous interface exists. Several attempts to establish a general balance equation not restricted to a particular flow regime have been done. But it appeared to the authors that these balance equations are nothing else than a particular form of the Leibniz rule for the surfaces. Therefore the application of these equations to the modeling of the VIA in two-phase flows is highly questionable. The issue of the establishment of a general balance equation for the VIA, able to deal with all two-phase flow regimes, remains open. From the experimental point of view, new instrumentation is available today to measure the volumetric interfacial area. The most promising method seems to be the use of local resistive or optical probes. Four-sensor probes are theoretically able to measure the local volumetric interfacial area whatever the flow regime if the following requirements are satisfied. The interfaces must always move in the flow and the smallest radius of curvature of the interfaces passing through the probe must be significantly larger than the probe size. The method has the inconvenient to be intrusive, but non intrusive methods, like the photographic method, are generally restricted to particular flow regimes like a bubbly flow regime characterised by low values of the void fraction. The two-sensor and four-sensor probes have been tested with success in the bubbly flow regime by several authors, up to the cap bubbly flow. We will try to use a four-sensor probe in the case of a stratified wavy flow in the CEA Grenoble. The application of these measuring techniques to the droplet flow case seems more difficult because of the small size of the droplets generally encountered, the high velocity of the droplets in a gas stream and the possibility that the droplets form liquid films on the probe. Therefore, for droplet flows, the use of a photographic method is perhaps preferable. From the numerical point of view, the use of a volumetric interfacial area balance equation in a code and the determination of the local flow regime from the calculated VIA necessitates a lot of modeling efforts, and numerous iterative comparisons to the experiments. In our opinion, the major difficulties are the prediction of a stratification or a destratification (transition from a dispersed flow regime to a flow regime with separated phases and vice-versa), and the phase inversion (when a bubbly flow becomes a droplet flow and vice versa). The VIA in a bubbly flow is typically much greater than the one in a stratified flow, and the source and sink terms governing the transition between these two regimes (for example the deposition rate of the bubbles on the free surface) are not easy to model. During a phase inversion (governed for example by a criterion based on the local value of the void fraction), the source terms of VIA for bubbles and droplets are not the same, and this can bring some discontinuities on the VIA during the calculation. This problem is due to the fact that the same balance equation is used for all the flow regimes. A solution to this problem could be to introduce several interfacial area balance equations : one for the bubbles surfaces, a second one for the droplets surfaces and possibly a third one for the free surface. This method has been used with success in the SIMMER code, where separated VIA balance equations are used for bubbles and droplets, but we believe that it is more difficult to use these VIA to determine the flow regime. At the moment, numerous authors use a VIA balance equation in their computer code for the case of bubbly-to-slug flow regimes. The issue of the possible extension of these balance equation to the other flow regimes should be addressed in the future.

Abstract The increasing popularity of flip-chips brings new challenges to those who must perform device analysis (1). Its ability to accommodate high pin-count and high bandwidth microprocessors, DSPs and complex logic devices is increasing the demand for this technology. Conventional e-beam and mechanical probing techniques currently allow quick and efficient analysis of conventional semiconductor devices. When the surface of the device is not exposed, however, conventional analysis techniques are insufficient and new techniques must be developed. Conventional packaging technologies allow design debug and failure analysis to be performed in a relatively straightforward manner. Analysis from the topside is clearly the preferred technique when possible (2), using specially prepared engineering prototypes, but backside access for dynamic timing analysis is required when topside techniques are exhausted. The flipchip process, however, makes topside analysis impractical in most situations. There are several different techniques that are currently being used for backside analysis. These are emission microscopy (3), optical beam induced current (OBIC) (4), and a combination of software and built in self-test/scan methods (5). These techniques are valuable in helping engineers to analyze and isolate faults for functional failures. These techniques do not, however, provide precise analog waveforms which may be used to perform timing analysis on the device. A backside pulsed laser electro-optic technique for measuring internal node timing (6) has been developed for waveform acquisition. Although this technique permits acquisition of waveforms from a bi-polar device which has had its substrate thinned, it has limited application to CMOS devices, particularly in long duty cycle applications. Milling the backside of devices in order to facilitate backside waveform acquisition is considered by some researchers as a potential approach, but the authors are not aware of any published data on this subject.