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The optimum design for an absorption grating-based D-PDT sensor is described.Density functional theory has been employed to determine ground state properties and calculate the complex dielectric function of the FeF2 compound. The complex expression of magnetic permeability has been estimated using the formula of the magnetic permeability tensor. To interpret the optical transitions, densities of states and projected densities of states have been determined. Suitable expressions for treating contributions of electric permittivity and magnetic permeability to optical properties have been derived and applied. The absorption coefficient in the visible range is a result of the transitions from the top of the valence band to 4s bands of Fe2+ cations in the conduction band. In the far-infrared region, FeF2 is a perfect reflector. The estimated optical properties show good agreement with previous theoretical and experimental results in the literature.A diffraction-limited lens having both surfaces conic is shown. The analytical and numerical calculation for all possible solutions of the conical front and back surfaces is presented. Object and image distances, lens thickness, and refractive index are prescribed. The process to obtain on-axis diffraction-limited images with bi-conic lenses and the proof of the method, corroborated through an example in Oslo, are described here.In relation to the computation of electromagnetic scattering in layered media by the Gabor-frame-based spatial spectral Maxwell solver, we present two methods to compute the Gabor coefficients of the transverse cross section of three-dimensional scattering objects with high accuracy and efficiency. The first method employs the analytically obtained two-dimensional Fourier transform of the cross section of a scattering object, which we describe by two-dimensional characteristic functions, in combination with the traditional discrete Gabor transform method for computing the Gabor coefficients. The second method concerns the expansion of the so-called dual window function to compute the Gabor coefficients by employing the divergence theorem. Both methods utilize (semi)-analytical approaches to overcome the heavy oversampling requirement of the traditional discrete Gabor transform method in the case of discontinuous functions. Numerical results show significant improvement in terms of accuracy and computation time for these two methods against the traditional discrete Gabor transform method.Wave structure function, coherence length, and angle-of-arrival variance are derived analytically for a Gaussian beam propagating in an underwater turbulent medium. The recently introduced oceanic turbulence optical power spectrum model [J. Opt. Soc. Am. A37, 1614 (2020)JOAOD60740-323210.1364/JOSAA.399150] is used, and results are obtained for the case of large separations. The effect of temperature, salinity, rates of dissipation of mean-squared temperature and energy, temperature-salinity gradient ratio, wavelength, and aperture diameter, is presented. Further, a Gaussian beam is compared with the plane and spherical waves in terms of their effect on wave structure function, coherence length, and angle-of-arrival fluctuations. The presented results can be beneficial to set the parameters of imaging and communication systems using a Gaussian beam in an underwater turbulent medium and can be used for the optimization of the design of these systems.We describe the discrete Laplacian deconvolution (DLD) method for reconstructing an image from its directional derivatives in multiple directions. The DLD models the derivative measurements as discrete convolutions and efficiently computes the ridge regression or the pseudoinverse estimate of the underlying image using the fast Fourier transform. We apply the method to differential interference contrast (DIC) microscopy, and show that under certain conditions, our proposed method is equivalent to the spiral phase integration (SPI) method. Unlike the SPI method, the DLD method can be used with more than two gradient measurement images. Selleckchem Fasoracetam We illustrate the use of DLD on both simulated and empirical DIC images, demonstrating image reconstruction performance improvements from using multiple gradient images.We extend the scalar elliptical multi-Gaussian Schell-model (EMGSM) beams with twist phase to the electromagnetic domain and obtain the analytical expression for the propagation of the electromagnetic twisted EMGSM beams through random media. The twist phase-induced changes of the spectral density and degree of polarization of such beams on propagation are studied numerically. Results show that by adjusting the twist factor and the correlated parameters of the source, both the spectral density and degree of polarization not only rotate around the propagation axis but also exhibit diverse shapes. The flattopped ellipse-like and diamond-like shape maintain over a relatively long propagation distance and finally involve into Gaussian-like shape due to stronger atmospheric turbulence. The results will be useful in optical trapping and optical communication.Localization microscopy approaches with enhanced depth-of-field (EDoF) are commonly optimized using the Cramér-Rao bound (CRB) as a criterion. It is widely believed that the CRB can be attained in practice by using the maximum-likelihood estimator (MLE). This is, however, an approximation, of which we define in this paper the precise domain of validity. Exploring a wide range of settings and noise levels, we show that the MLE is efficient when the signal-to-noise ratio (SNR) is such that the localization standard deviation of a single molecule is less than 20 nm. Thus, our results provide an explicit and quantitative validity boundary for the use of the MLE in EDoF localization microscopy setups optimized with the CRB.In this paper, an efficient modeling method for a photonics-focusing grating coupler is proposed and studied. The focusing grating coupler can be divided into two parts the cylindrical coordinate slab waveguide and the Cartesian coordinate slab waveguide. Using the cylindrical slab modes and the two-dimensional complex mode-matching method, we can obtain the efficient compact model for the focusing grating coupler. This model reduces the three-dimensional structure into a two-dimensional structure by using the effective index method to reduce the computation time as well as the computational resources. The simulation result, which is dependent on the finite-difference time-domain method, demonstrates the accuracy of the advanced compact model. This model can also be integrated into the circuit simulation.Counterphase flicker is perceptible consequent on the nonlinearity between each retina and binocular fusion. This paper models that nonlinearity in terms of the radio reception technology of the early twentieth century. The nonlinearity is probably realized in the retinal ganglion cells.In the context of adaptive optics for astronomy, one can rely on the statistics of the turbulent phase to assess a part of the system's performance. Temporal statistics with one source and spatial statistics with two sources are well known and widely used for classical adaptive optics systems. A more general framework, including both spatial and temporal statistics, can be useful for analysis of the existing systems and to support the design of future ones. In this paper, we propose an expression of the temporal cross power spectral densities of turbulent phases in two distinct beams, which is from two different sources to two different apertures. We consider the phase either as it is, without a piston, or as its decomposition on Zernike modes. The general formulas allow coverage of a wide variety of configurations, from single-aperture to interferometric telescopes equipped with adaptive optics, with the possibility to consider apertures of different sizes and/or sources at a finite distance. The presented approach should lead to similar results with respect to existing methods in the Fourier domain, but it is focused on temporal frequencies rather than spatial ones, which might be convenient for some aspects such as control optimization. To illustrate this framework with a simple application, we demonstrate that the wavefront residual due to the anisoplanatism error in a single-conjugated adaptive optics system is overestimated when it is computed from covariances without taking into account the temporal filtering of the adaptive optics loop. We also show this overestimation in the case of a small-baseline interferometer, for which the two beams are significantly correlated.Measures of purity for 3D partially polarized fields, and in particular, the separation into circularly and linearly polarized contributions, are reexamined, and a new degree of total linear polarization introduced. Explicit expressions for the characteristic decomposition in terms of coherency matrix elements are presented, including the special case of an intrinsic coherency matrix. Parameterization of the coherency matrix in terms of ellipticity, and the directions of the ellipse normal and major axis are investigated. Phase consistency is discussed. A comprehensive collection of results regarding intrinsic polarization properties is presented.Autofocusing Airy-like beams have been designed based on the self-accelerating beams along arbitrary polynomial paths. The evolutions of the autofocusing beam in free space and turbulent atmosphere have been studied. Results show that the energy concentration of the autofocusing beam near the focal plane has a close relationship with its accelerating trajectory. The spot size of the autofocusing beam in the focal plane varies with the acceleration trajectory. The influence of turbulence on different autofocusing beams is different and has a relation with the degree of the curvature of the accelerating beam. The autofocusing beam propagating along a small curvature path has better resistance against turbulence.This feature issue is a continuation of a tradition, since 2007, to follow the conclusion of the OSA Topical Meeting on Digital Holography and 3D Imaging (DH+3D). It addresses current research topics in digital holography (DH) and 3D imaging that are also in line with the topics of Applied Optics (AO) and the Journal of the Optical Society of America A (JOSA A).By using the recent theory of elemental scattering matrix, I study the critical-point behaviors of conically mounted and crossed gratings in Littrow mountings. As functions of the projected incident wave vector in the grating plane, the (m, n)th-order reflected principal diffraction efficiencies (the maximum and minimum diffraction efficiencies of a diffraction order for all possible incident polarizations) of a crossed grating have C2 symmetry with respect to the (m, n)th-order Littrow point, and for a conically mounted grating, the symmetry type is increased to C2v. In a Littrow mounting, each one of the two principal diffraction efficiencies, independent of the other, can only be at one of the three possible states a local maximum, a local minimum, or a saddle point of an even (most likely the second) degree. If the grating is mirror-symmetric with respect to a plane parallel to the grating's mean plane, the results hold for a transmitted diffraction order as well.