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

{"title":"Color formation as a Hilbert space operator: quotient structures and limits of metamerism.","authors":"Peter Morovic, Ján Morovic","doi":"10.1364/JOSAA.606555","DOIUrl":"https://doi.org/10.1364/JOSAA.606555","url":null,"abstract":"<p><p>Color formation, the mapping from spectral reflectances through an illuminant and observer to color responses, is a bounded linear operator from a Hilbert space of spectral functions to the space <i>R</i>^C of color responses, where <i>C</i> is the number of sensor classes of the observer (<i>C</i>=3 for a trichromat). This paper develops the algebraic ecosystem of this framework and uses it to establish two results on the limits of metamerism. Metameric equivalence classes are cosets of the kernel, making color space the quotient <i>L</i>²/ker(W); the pseudoinverse is the canonical section selecting minimum-norm representatives; physical constraints cut each coset to a compact convex body whose image is the object-color gamut (a zonotope); and two complementary types of domain restriction, linear-model bases and convex-combination \"naturalness\" domains, transfer the algebraic structure to a finite-dimensional effective operator. Within this framework we prove: <i>(i)</i> non-trivial absolute metamers, reflectance pairs that match under every possible illuminant, cannot exist as long as every wavelength excites at least one photoreceptor class; <i>(ii)</i> a two-sided dimensional threshold for metamers stable across a restricted family of illuminants: such metamers exist whenever the illuminant family spans fewer than ⌈<i>S</i>/<i>C</i>⌉ dimensions, where <i>S</i> is the number of sampled wavelengths, and cannot exist once the stacked operator attains full rank-e.g., for a trichromatic observer (<i>C</i>=3) and the CIE daylight family, whose span has dimension <i>d</i>=2 or 3, in an <i>S</i>=31-dimensional spectral representation this threshold is far from being reached. The existence half of (ii) was given in discrete form by Burns, Cohen, and Kuznetsov and in dual form by Brainard, Wandell, and Cowan, both in 1989. What is added here is the impossibility direction, the two-sided threshold, and its transport to a restricted domain. A worked example with the CIE 1931 observer under D65, the CIE daylight basis, and a 10-dimensional PCA basis of the SOCS dataset illustrates the theory and constructs daylight-absolute metamer pairs by linear programming. A companion paper [J. Opt. Soc. Am. A (to be published)] extends the framework to two operators, treating metamer mismatching and chromatic adaptation.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1614-1623"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of coherence length and related parameters in anisotropic Kolmogorov jet engine exhaust turbulence.","authors":"Yahya Baykal","doi":"10.1364/JOSAA.612472","DOIUrl":"https://doi.org/10.1364/JOSAA.612472","url":null,"abstract":"<p><p>Coherence length defined as the propagation distance over which a coherent wave maintains a specified degree of coherence is one of the main parameters in optical wireless communication (OWC). Knowledge about coherence length is important in the design of OWC systems operating in turbulent media. Such information is used in mitigating the turbulence degradation and enhancing the system performance in OWC links. Coherence length is also utilized in determining many entities in optical wave propagation in turbulence such as average intensity, transmittance, beam spreading, mutual coherence function, and scintillation index. In jet engine exhaust turbulence, coherence length becomes even more important since in such media, strong turbulence regimes are experienced over short link distances. Coherence length variations in anisotropic Kolmogorov jet engine exhaust turbulence are evaluated against the link, turbulence parameters, and anisotropic factors. Parameters related to the coherence length such as the atmospheric coherence time and the minimum number of required actuators on a deformable mirror for improving the performance of anisotropic jet engine exhaust are also presented. Results reported in this paper will help OWC engineers and researchers in promoting the use of OWC links operating especially in airports.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1558-1563"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generation of perfect vector vortex beams and their propagation in atmospheric turbulence.","authors":"Yayun Ma, Lizi Xin, Fen Yang, Dong'e Zhao","doi":"10.1364/JOSAA.609069","DOIUrl":"https://doi.org/10.1364/JOSAA.609069","url":null,"abstract":"<p><p>Perfect vector vortex beams (PVVBs) carry orbital angular momentum (OAM) and exhibit self-focusing and self-healing properties, showing great application potential in free-space optical communication. Based on the pixelated complex amplitude encoding algorithm, we experimentally generate parameter-tunable PVVBs. The multi-phase screen method was adopted for numerical simulations to investigate the propagation characteristics of parameter-varied PVVBs in atmospheric turbulence. Through a comparative analysis of beam wander, beam expansion, and intensity scintillation under corresponding conditions, it is found that the evolution of beam intensity has a notable impact on propagation effects. During the self-focusing stage, beam wander and beam expansion increase significantly as turbulence intensity strengthens, whereas the scintillation index tends to plateau, resulting in scintillation saturation. Increasing the topological charge enlarges the effective beam radius; additionally, a larger topological charge mitigates turbulence-induced disturbances, leading to a slower radius expansion rate as turbulence intensity increases. Increasing the ring radius or decreasing the ring width can reduce light intensity scintillation and increase the effective beam radius. The scintillation index decreases gradually as the polarization state approaches that of cylindrical vector beams, indicating that rational modulation of the beam polarization state is an effective and feasible approach to suppress intensity scintillation. This research offers valuable insights for the application of PVVBs in atmospheric microwave remote sensing, aerospace, and military defense scenarios.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1595-1604"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hardware-calibrated optical spiking neural network based on a programmable MZI mesh weight engine.","authors":"Dingmin Cheng, Rong Wang, Hang Zhang, Ling Zhang, Duan Huang","doi":"10.1364/JOSAA.608366","DOIUrl":"https://doi.org/10.1364/JOSAA.608366","url":null,"abstract":"<p><p>Phase-change-material (PCM) synapses and all-optical spiking neurons provide a promising neuromorphic-computing framework for on-chip photonic neural networks. However, PCM weights mainly rely on absorption-based transmittance modulation, which is intrinsically more suitable for non-negative weights. When signed real-valued or complex-valued weight matrices obtained by backpropagation are implemented, differential synapse pairs are usually required, thereby increasing device count, insertion loss, and programming errors. This paper proposes a hybrid photonic-neural network simulation framework that employs a wavelength-division multiplexing (WDM) structure to implement optical signal fan-out and channel allocation. The weight matrices are implemented using a programmable Mach-Zehnder interferometer (MZI) array, and a hybrid offline-online configuration calibration strategy is employed to compensate for hardware errors. Matrix-level simulations on the MNIST dataset show that, under the proposed network architecture, the PCM differential-synapse model achieves 92.39% accuracy, whereas the uncalibrated MZI weight-matrix scheme reaches 87.15%. After online calibration, the MZI scheme recovers to 92.59%. Further matrix-fidelity analysis shows that the PCM baseline reaches approximately 96% average fidelity. The uncalibrated MZI scheme achieves about 78.00% fidelity, whereas calibration improves the fidelity of the two layers to 97.53% and 97.40%, respectively. These results demonstrate that the proposed method enhances the expressive power of the weight matrix and improves the correctability of hardware errors while retaining the advantages of the original optical pulse network architecture. This work provides a viable path toward the construction of scalable optical neural networks.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1605-1613"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimum-transmission free-space optical communications.","authors":"Prajit Dhara, Babak N Saif, Jeffrey H Shapiro, Saikat Guha","doi":"10.1364/JOSAA.604132","DOIUrl":"https://doi.org/10.1364/JOSAA.604132","url":null,"abstract":"<p><p>Slepian developed the prolate spheroidal wavefunction (PSW) spatial-mode basis, which forms the normal modes of the Fresnel-propagation kernel of a free-space optical communications channel bookended by hard-circular apertures. The zero-th-order PSW mode exhibits the highest power-transfer eigenvalue, thereby maximizing transmissivity for single-spatial-mode communications [Bell Syst. Tech. J.43, 3009 (1964)BSTJAN0005-858010.1002/j.1538-7305.1964.tb01037.x, J. Opt. Soc. Am.55, 1110 (1965)10.1364/JOSA.55.001110]. We show that the transmissivity performance of this fundamental PSW mode can be obtained by an aperture-truncated Gaussian beam of an optimized beam waist, despite the two mode shapes deviating from one another in the near-field regime.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1544-1550"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short-term turbulence beam spread revisited.","authors":"Mikhail Charnotskii","doi":"10.1364/JOSAA.608506","DOIUrl":"https://doi.org/10.1364/JOSAA.608506","url":null,"abstract":"<p><p>The short-term (ST) turbulent beam spread theory proposed by Charnotskii [Proc. SPIE1968, 389-400 (1993)10.1117/12.154845] was tested against wave-optics simulations and found that it underestimated the degree of turbulent beam spread and exhibited some artifacts in the ST irradiance profiles. We discuss the reasons for the shortcomings of the 1993 model and propose what is believed to be a new model of the ST wave structure function. This model maintains the same level of computational complexity as the 1993 model but shows better agreement with the simulation results.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1538-1543"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conic sections arising from light reflection, refraction, and diffraction.","authors":"Xiao Wang, Kongo Lai, Shengtai Zhu, R John Koshel, José Sasián","doi":"10.1364/JOSAA.604910","DOIUrl":"https://doi.org/10.1364/JOSAA.604910","url":null,"abstract":"<p><p>Astigmatic focal loci govern field-dependent imaging behavior in optical systems. We derive the spatial loci of the local tangential and sagittal focal positions as the object point varies continuously along a meridional field line in a flat object plane. We show that, within the Coddington formulation, these loci range from simple low-order geometries-including lines, planes, and conic sections-to higher-order algebraic curves, depending on the physical interaction at the interface and the object position. For a real object and a concave non-diffractive spherical mirror, the tangential locus is an exact conic whose eccentricity is determined by the normalized object coordinate <i>L</i>/<i>R</i>, with <i>e</i>=<i>R</i>/(2<i>L</i>), where <i>R</i> is the algebraic radius of curvature of the surface and <i>L</i> is the algebraic axial coordinate of the object plane. In contrast, the refractive spherical surface retains a quadratic sagittal locus but generally produces a higher-order tangential locus, while the one-dimensional spherical gratings considered here generically give rise to higher-order field-dependent loci. Under the separate Rowland object-space condition, the tangential focal locus reduces to the same circular form for spherical mirrors, refractive spherical surfaces, and the spherical gratings considered here. These results extend the Coddington framework from a local description of astigmatism to a field-wide geometric characterization of the focal structure.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1551-1557"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical investigation of the effect of the spatial coherence of incident light on the Talbot and Lau self-images.","authors":"Javad Arefitabar, Khosrow Hassani","doi":"10.1364/JOSAA.608666","DOIUrl":"https://doi.org/10.1364/JOSAA.608666","url":null,"abstract":"<p><p>Using binary gratings as test objects, we quantitatively investigate the formation and visibility of the Talbot and Lau self-images under partially coherent illumination generated by a secondary Gaussian Schell-model source. The spatial coherence of the illuminating field is controlled through continuous variation of the source size, resulting in different fringe distributions in both regimes. Although the spatial coherence length varies according to a Lorentzian function with the source size, the visibility of the Talbot self-images exhibits an approximately Gaussian dependence, decreasing to 0.5 when the coherence length at the grating plane becomes nearly twice the grating pitch. In the Lau regime, the self-images remain sharp and clearly visible over a broad range of low-coherence illumination, as long as the coherence length remains below approximately twice the pitch of the first grating. However, when the coherence length becomes comparable to the grating pitch yet much smaller than the transverse width of the incident light field, the illumination becomes locally coherent over individual grating periods. Consequently, Fresnel diffraction features produced by the gratings appear within the main Lau self-image on the CCD plane, superimpose on the Lau fringes, and degrade their regular structure.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 10","pages":"1638-1649"},"PeriodicalIF":1.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149111423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linearizing phase retrieval: the theory of near-focus interference.","authors":"Martin Berz, Christoph Dillitzer, Stefanos Kekkas, Johannes Pittrich, Hristo Iglev, Oliver Hayden","doi":"10.1364/JOSAA.603931","DOIUrl":"https://doi.org/10.1364/JOSAA.603931","url":null,"abstract":"<p><p>Phase retrieval from square-law detectors in common path is traditionally a nonlinear, nonconvex inverse problem requiring complex iterative algorithms. Near-focus interference (NFI) uniquely enables direct linearization of self-referential phase retrieval. NFI exploits the interference between the longitudinal evolution of a coherent wavefield over a short free-space propagation-just a few Rayleigh distances-and the unpropagated self. NFI equations assume nothing about the complex fields except that they are bandlimited and fully represented on a sampling grid. Rigorous theory shows the reconstructed complex field is unique and depends continuously on the measured interference term and a single intensity, ensuring stability. Numerically, NFI is applied to bright-field and pure dark-field microscopy via projection onto a discrete hexagonal basis and a coordinate-free Krylov subspace least-squares analysis (LSA). In bright field, the phase locks to the known background field. In dark field, a data-driven bootstrap provides an initial guess for the LSA, resolving the global phase factor ambiguity common to self-referential measurements. Numerical simulations with 8-bit noise show recovery of 900 independent scatterers in 5 iterations. Experimental bright-field results are shown for samples much larger than the defocused diffraction spot. Beyond these guarantees of uniqueness and continuity, the principal practical advantage of NFI over state-of-the-art quantitative phase imaging is self-calibration: the propagation operator and the complex field are recovered directly from the noisy measurement, without external calibration standards, and the same reconstruction is obtained even after realignment of the instrument. These properties provide a foundation for standardized quantitative phase imaging across instruments and laboratories, facilitating adoption in medical diagnostics.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 9","pages":"1420-1434"},"PeriodicalIF":1.5,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149167327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-source imaging with <i>δ-SP_N</i> approximation based fluorescence optical tomography.","authors":"Nishigandha Patil, Naren Naik","doi":"10.1364/JOSAA.593274","DOIUrl":"https://doi.org/10.1364/JOSAA.593274","url":null,"abstract":"<p><p>In a recent work, we developed the <i>δ</i>-SP_N approximation, a low-order approximation to the radiative transfer equation that provides improved estimates of fluence in the near source when directed sources and scattering are considered. In this work, we present reconstruction frameworks and a detailed numerical study to demonstrate the use of the <i>δ</i>-SP_N approximation for mesoscopic fluorescence optical tomography applications in reflectance-mode imaging in the near-source region. Comparisons are presented with the standard SP_N approximation to highlight the improvements afforded by the use of the <i>δ</i>-SP_N approximation. We investigate the effect of improved modeling using two different reconstruction schemes, namely, the regularizing Levenberg-Marquardt and a total-variation regularization scheme with measurement data obtained via Monte Carlo simulations over a wide range of test cases. With the <i>δ</i>-SP_N approximation, better localization, improved volume recovery, and consistent estimates across different reconstruction schemes are observed. The improvement is significant for test cases with two objects, shallow domain as well as oblique incidence scenarios, where the standard SP_N approximation consistently fails across both the reconstruction schemes.</p>","PeriodicalId":17382,"journal":{"name":"Journal of The Optical Society of America A-optics Image Science and Vision","volume":"43 9","pages":"E31-E41"},"PeriodicalIF":1.5,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149169735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}