Physical optics

About: Physical optics is a research topic. Over the lifetime, 5342 publications have been published within this topic receiving 101388 citations. The topic is also known as: wave optics.

Late-time target response measured with terahertz impulse ranging

Abstract: Time-domain impulse-scattering measurements of freely propagating single cycle terahertz radiation from dielectric targets is measured in the far field with subpicosecond resolution. Initial specular reflection as well as late-time response of the targets is observed to approximately 100 times the initial pulse width. Measured scattered fields agree well with the calculated scattering for early- and late-time response in both the time and frequency domains. The data is fit to both an inverse Fourier transform of numerically calculated frequency domain scattering as well as an intuitive model based on physical optics (PO). The PO picture is verified directly in the time domain and surface wave propagation velocities are measured.

PO/Mec-Based Scattering Model for Complex Objects on a Sea Surface

Abstract: In this contribution a model based on asymptotic methods is proposed to compute the scattered fleld from complex objects on a sea surface. The scattering model combines the geometrical optics, the physical optics and the method of equivalent currents. It includes the shadowing efiects and multiple-bounce up to order 3. This model is used, in the following, for Radar Cross Section (RCS) estimation and to generate Synthetic Aperture Radar (SAR) raw data for imaging applications. The theoretical aspects are reviewed in this paper and the proposed model is detailed. Numerical results are provided to validate the approach through the computation of RCS for canonical objects and complex scenes. Both the bistatic and the monostatic conflgurations are studied in this work. Finally some flrst results dealing with SAR imaging of objects on a sea surface are provided. These images are constructed from the simulated raw data thanks to a chirp scaling-based algorithm.

The physical optics method in electromagnetic scattering

Abstract: The purpose of this work is to analyze the physical optics method as applied to electromagnetic scattering theory and to point out its physical and mathematical drawbacks. The main conclusions are (1) that the boundary values assumed by physical optics lead to electromagnetic fields that do not satisfy the finiteness of energy condition and, as a consequence, that integral representations of these fields cannot be obtained via the divergence theorem; (2) that the commonly accepted representations are not solutions of the physical optics problem because they fail to reproduce the assumed discontinuities of the fields on the scatterer. Despite the above conclusions, the present work should not be construed as an attempt to discredit the method but rather as an effort toward a better understanding of it. As it is well known, there have been a number of occasions in which physical optics has yielded quite satisfactory results.

The rotating wave approximation (RWA) of quantum optics: serious defect

Abstract: The rotating wave approximation (RWA) is an integral part of the foundations of quantum optics and it is also used extensively in atomic and condensed-matter physics. Here we prove that the model has a serious defect, viz. the spectrum has no lower bound, for all models of physical interest. As a result, the reservoir is not passive (since energy can be extracted from it without limit) and hence the second law of thermodynamics is not satisfied. An alternative to the RWA is discussed.