Journal of The Optical Society of America A-optics Image Science and Vision最新文献

Binary annular masks have recently been proposed to extend the depth of field (DoF) of single-molecule localization microscopy. A strategy for designing optimal masks has been introduced based on maximizing the emitter localization accuracy, expressed in terms of Fisher information, over a targeted DoF range. However, the complete post-processing pipeline to localize a single emitter consists of two successive steps: detection, where the regions containing emitters are determined, and localization, where the sub-pixel position of each detected emitter is estimated. Phase masks usually optimize only this second step. The presence of a phase mask also affecting detection, the purpose of this paper is to quantify and mitigate this effect. Using a rigorous framework built from a detection-oriented information theoretical criterion (Bhattacharyya distance), we demonstrate that in most cases of practical significance, annular binary phase masks maximizing Fisher information also maximize the detection probability. This result supports the common design practice consisting of optimizing a phase mask by maximizing Fisher information only.

The aims of the study were (1) to compare the accuracy and intrasession variability of noncycloplegic autorefraction (AR) obtained by a photorefractor and conventional and open-field autorefractors and (2) to evaluate the impact of accommodative and binocular vision anomalies on the accuracy of autorefraction. Twenty-nine children and adolescents aged 8-18 years were examined. All instruments gave more myopic results than subjective refraction (SR). Mean differences between the SR and the AR were +0.52/-0.25×96^∘ for the photorefractor, +0.63/-0.31×93^∘ for the conventional autorefractor, and +0.19/-0.26×94^∘ for the open-field instrument. The photorefractor appeared to be the most repeatable. The impact of the examined vision anomalies on the accuracy of autorefraction was not statistically significant.

The generation of three-dimensional tunable vector optical cages through full polarization modulation requires complex polarization states. This paper takes the vector Airy optical cage as an example to generate a three-dimensional tunable high-quality optical cage based on the Pancharatnam-Berry phase principle. The proposed method in this paper possesses the capability of arbitrary modulation in various aspects, including the quantity of optical cages and their respective sizes as well as three-dimensional spatial positions. Moreover, the intensity of each optical cage can be modulated independently. This research will improve the capture efficiency of optical tweezers and promote further development in fields of efficient optical trapping, particle manipulation, high-resolution microscopic manipulation, and optical communication.

A memory-efficient implementation scheme for the discontinuous Galerkin volume integral equation method (DGVIE) using Schaubert-Wilton-Glisson (SWG) basis functions is proposed to analyze electromagnetic scattering from inhomogeneous dielectric objects. For this proposed scheme, almost no half-SWG basis functions are needed for the elements separating nonconformal meshes, while these half-SWG basis functions are indispensable for the conventional DGVIE-SWG method. This is realized by applying the divergence-free condition of the electric displacement vector explicitly for nonconformal meshes separating neighboring subdomains of an inhomogeneous dielectric body. Therefore, the number of unknowns of the conventional DGVIE method can be further reduced. As a result, the memory of the proposed DGVIE method is only about half of the conventional one for inhomogeneous dielectric problems. Meanwhile, the total solution time has been reduced by the use of the proposed scheme. Particularly, the proposed DGVIE-SWG method is efficient in memory usage not only for inhomogeneous dielectric cases with high contrast ratio but also for cases with relatively low contrast ratio.

Large field-of-view optical imaging systems often face challenges in the presence of space-variant degradation. The existence of degradation leads to target detection and recognition being difficult or even unsuccessful. To address this issue, this paper proposes an adaptive anisotropic pixel-by-pixel space-variant correction method. First, we estimated region acquisition of local space-variant point spread functions (PSFs) based on Haar wavelet degradation degree distribution, and obtained initial PSF matrix estimation with inverse distance weighted spatial interpolation. Then, we established a pixel-by-pixel space-variant correction model based on the PSF matrix. Third, we imposed adaptive sparse regularization terms of the Haar wavelet based on the adaptive anisotropic iterative reweight strategy and non-negative regularization terms as the constraint in the pixel-by-pixel space-variant correction model. Finally, as the correction process is refined to each pixel, the split-Bregman multivariate separation solution algorithm was employed for the pixel-by-pixel spare-variant correction model to estimate the final PSF matrix and the gray value of each pixel. Through this algorithm, the "whole image correction" and "block correction" is avoided, the "pixel-by-pixel correction" is realized, and the final corrected images are obtained. Experimental results show that compared with the current advanced correction methods, the proposed approach in the space-variant wide field correction of a degraded image shows better performance in preserving the image details and texture information.

Airplanes use heavy wired harnesses to provide multimedia services to the seats. Optical wireless communications (OWC) are a natural choice to reduce the amount of weight, reduce the wiring complexity, and avoid possible spurious electromagnetic radiation that risks affecting the airplane's navigation systems. The light's dual use as lighting and optical communications functionalities allows for providing light and multimedia content through the reading lamp. Thus, an optical system using optical fibers to replace wires and a reading lamp can provide a cabin seat with lighting and onboard connectivity. However, changing shielded harnesses by optical fibers is-from an optical design point of view-a challenging task as the reading lamp must also meet the stringent requirements to link the optical wireless transmissions to the optical fiber. The difficulty up to now lies in injecting the light emitted from the passenger's device into the optical fiber using the reading lamp as the receiving antenna and light injector. Here, we describe a proof-of-concept device that experimentally allowed for establishing a link between a transmitter and a photodetector coupled to an optical fiber-end, i.e., the link consisted of an optical wireless communication and the launching of the light modulated signal into an optical fiber. Additionally, from the experimental experience, we will describe the optical design strategies permitting designing a compound freeform concentrator to allow optical free space-to-fiber links.

Propagation of a laser beam through the Rayleigh-Bénard (RB) convection is experimentally investigated using synchronous optical wavefront and intensity measurements. Experimental results characterize the turbulence strength and length scales, which are used to inform numerical wave optic simulations employing phase screens. Experimentally found parameters are the refractive index structure constant, mean flow rate, kinetic and thermal dissipation rates, Kolmogorov microscale, outer scale, and shape of the refractive index power spectrum using known models. Synchronization of the wavefront and intensity measurements provide statistics of each metric at the same instance in time, allowing for two methods of comparison with numerical simulations. Numerical simulations prove to be within agreement of experimental and published results. Synchronized measurements provided more insight to develop reliable propagation models. It is determined that the RB test bed is applicable for simulating realistic undersea environments.

Previous psychophysical studies have demonstrated that the image orientation of textured surfaces guides human 3D shape perception. However, the accuracy of computational 3D shape reconstruction solely from image orientation requires further study. This paper proposes a 3D shape recovery algorithm from the image orientation of a single textured surface image. The evaluation of the proposed algorithm uses computer-generated textured complex 3D surfaces. The depth correlations between the recovered and true surface shapes achieved or exceeded 0.8, which is similar to the accuracy of human shape perception, as shown in a previous psychophysical study, indicating that the image orientations contain adequate information for 3D shape recovery from textured surface images.

In wafer metrology, the knowledge of the photomask together with the deposition process only reveals the approximate geometry and material properties of the structures on a wafer as a priori information. With this prior information and a parametrized description of the scatterers, we demonstrate the performance of the Gauss-Newton method for the precise and noise-robust reconstruction of the actual structures, without further regularization of the inverse problem. The structures are modeled as 3D finite dielectric scatterers with a uniform polygonal cross-section along their height, embedded in a planarly layered medium. A continuous parametrization in terms of the homogeneous permittivity and the vertex coordinates of the polygons is employed. By combining the global Gabor frame in the spatial spectral Maxwell solver with the consistent parametrization of the structures, the underlying linear system of the Maxwell solver inherits all the continuity properties of the parametrization. Two synthetically generated test cases demonstrate the noise-robust reconstruction of the parameters by surpassing the reconstruction capabilities of traditional imaging methods at signal-to-noise ratios up to -3d B with geometrical errors below λ/7, where λ is the illumination wavelength. For signal-to-noise ratios of 10 dB, the geometrical parameters are reconstructed with errors of approximately λ/60, and the material properties are reconstructed with errors of around 0.03%. The continuity properties of the Maxwell solver and the use of prior information are key contributors to these results.

The camera function of a smartphone can be used to quantitatively detect urine parameters anytime, anywhere. However, the color captured by different cameras in different environments is different. A method for color correction is proposed for a urine test strip image collected using a smartphone. In this method, the color correction model is based on the color information of the urine test strip, as well as the ambient light and camera parameters. Conv-TabNet, which can focus on each feature parameter, was designed to correct the color of the color blocks of the urine test strip. The color correction experiment was carried out in eight light sources on four mobile phones. The experimental results show that the mean absolute error of the new method is as low as 2.8±1.8, and the CIEDE2000 color difference is 1.5±1.5. The corrected color is almost consistent with the standard color by visual evaluation. This method can provide a technology for the quantitative detection of urine test strips anytime and anywhere.