Wave Optics Ppt Free Download

From left to right: confocal NLOS deconvolution, FBP and our proposed method. Top row represents a non-retroreflective object; bottom row represents a retroreflective object captured in sunlight. In the presence of noisy data, FBP fails. Confocal NLOS includes a Wiener filter that needs to be explicitly estimated. Our phasor-field virtual wave method yields better results automatically. This is particularly important in complex scenes with interreflections, where the background is not uniform across the scene, and the noise level cannot be reliably estimated.

In other words, the core contribution and motivation for this work is enabling the application of a much wider range of rendering and light transport tools to wave optics, and not so much the reproduction of some appearance or particular visual effect.

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Classical rendering techniques rely on a linear rendering equation to (Monte-Carlo) integrate; they also require propagating local packets of energy (for example, a ray) in order to: (i) make use of spatial-subdivision accelerating structures, crucial to making path tracing an $\mathcal{O}(\log n)$ algorithm instead of linear; and, (ii) simplify the formulation of light-matter interaction, which now happen at a localized point, and not over a region containing multiple, mutually-interfering scatterers.If you forgo linearity and locality, you need to consider the mutual interference of the entire scene with itself, for example via highly-impractical wave solving.

Previous work that targets wave-optical rendering, for example A Generic Framework for PLT and Towards Practical Physical-Optics Rendering, regains a degree of locality and linearity by propagating forward partially-coherent light.Because such a decomposition depends on the wave properties of light, these properties need to be known in order to propagate light and evaluate its interaction with matter.This can be quite limiting in the kind of rendering tools we may use.While these previous work are able, at least in theory, to render any scene that you see in this paper, when the light transport gets complex, as in the snake enclosure scene, previous work will require a practically-impossible number of samples and runtime.

Classical wave optics is a branch of physics that studies the behavior of light as a wave. It focuses on the propagation, diffraction, and interference of light, as well as its interactions with matter.

Some open problems in classical wave optics include understanding the behavior of light in complex media, developing new optical imaging techniques, and improving the efficiency of optical devices such as lasers and photodetectors.

Current research efforts in classical wave optics include studying the properties of metamaterials, developing new methods for controlling light at the nanoscale, and exploring the potential of quantum optics for information processing and communication.

If you are interested in classical wave optics, you can pursue a degree in physics or engineering, or join a research group at a university or research institution. You can also attend conferences and workshops to learn more about the latest developments in the field and network with other scientists in the field.

Non-line-of-sight (NLOS) imaging allows to observe objects partially or fully occluded from direct view, by analyzing indirect diffuse reflections off a secondary relay surface. Despite its many potential applications, existing methods lack practical usability due to several shared limitations, including the assumption of single scattering only, lack of occlusions, and Lambertian reflectance. Line-of-sight (LOS) imaging systems, on the other hand, can address these and other imaging challenges despite relying on the mathematically simple processes of linear diffractive wave propagation. In this work we show that the NLOS imaging problem can also be formulated as a diffractive wave propagation problem. This allows to image NLOS scenes from raw time-of-flight data by applying the mathematical operators that model wave propagation inside a conventional line-of-sight imaging system. By doing this, we have developed a method that yields a new class of imaging algorithms mimicking the various capabilities of LOS cameras. To demonstrate our method, we derive three imaging algorithms, each with its own unique novel capabilities, modeled after three different LOS imaging systems. These algorithms rely on solving a wave diffraction integral, namely the Rayleigh-Sommerfeld Diffraction (RSD) integral. Fast solutions to RSD and its approximations are readily available, directly benefiting our method. We demonstrate, for the first time, NLOS imaging of complex scenes with strong multiple scattering and ambient light, arbitrary materials, large depth range, and occlusions. Our method handles these challenging cases without explicitly developing a light transport model. We believe that our approach will help unlock the potential of NLOS imaging, and the development of novel applications not restricted to laboratory conditions, as shown in our results.

Measurement and phasor field on the scanning wall. The image on the left side shows the hardware scanning. The right image shows the virtual phasor field of the hidden scene (Global and Local display range for each frame). Notice that this raw virtual phasor field wavefront contains the direct and indirect signal of the hidden scene, interestingly we can also notice the shadow of the chair at around Time index:800.

Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method.

Part II of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and time-dependent thermal blooming (TDTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 m, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number, the number of wind-clearing periods, and the distortion number to gauge the strength of the simulated turbulence and TDTB. These parameters simply greatly given propagation paths with constant atmospheric conditions. In addition, we use the log-amplitude variance and the branch-point density to quantify the effects of TTBI. These metrics result from a point-source beacon being backpropagated from the target plane to the source plane through the simulated turbulence and TDTB. Overall, the results show that the log-amplitude variance and branch-point density increase significantly due to TTBI. This outcome poses a major problem for beam-control systems that perform phase compensation.

Computational high-frequency electromagnetics software uses an array of general-purpose numerical methods, including finite-difference, spectral, method-of-moments, and finite-element methods. Equipped with these tools, engineers can analyze propagating waves in optical structures with a minimal set of physical assumptions.

Over the years, these methods have been successfully applied to the analysis of important optical components such as optical fibers, directional couplers, and ring resonators. These general methods are sometimes referred to as full-wave methods. The name conveys that there are no inherent approximations other than those coming from creating a digital model by discretizing the piecewise continuous optical media. In this way, phenomena such as diffraction and low-order mode resonances can be captured by virtually arbitrary accuracy by simply refining the level of discretization.

In the case of the finite-difference method, refining the level of discretization roughly means inserting more points in the computational domain so that the electromagnetic field can be represented in a smoother fashion, and similarly for the other methods. However, more discretization points means higher computational cost. For a 3D analysis, the number of discretization points, or elements, scale as the cube of the wavelength because of the Nyquist criterion (see Fig. 1). At least two sampling points per wavelength are needed in each coordinate direction, and even more in practice. The actual computational cost of the underlying numerical methods typically scales even worse, which implies that such full-wave methods are of limited use for cases where the relative number of wavelengths of the object of interest is large. e24fc04721