It also benefits the development of autofocusing 3D measurement technology.The direct pickup of integral imaging typically needs to overcome limitations especially the restricted depth of field (DoF) under a lenslet array. In order to solve the problem, we design a motion parallax enhancing approach for three-dimensional (3-D) integral optical display only relying on a commercial Lytro camera. First, the non-uniform axial compression from the zoom lens of the Lytro camera is analyzed and experimentally investigated. Next, using depth slicing, locating and retargeting, the parallax of the integral optical display is significantly enhanced. Additionally, the displayed depth information can be presented in a uniform compression with the same proportion as the real scene even without the prior knowledge of the actual object distance. The experimental results prove the feasibility of the proposed method, which provides an efficient way for the acquisition of the elemental image array. Additionally, it is also a new attempt to expand the application scope of the Lytro camera from 2-D refocusing to the content acquisition for the integral display.Acquisition, tracking, and pointing (ATP) mechanisms are generally adopted for optical wireless communications (OWCs) to maintain a strict alignment state for reliable communication. ATP mechanisms conventionally employ beacon lights to determine the orientation of the remote optical terminal. They typically cannot maintain a steady alignment under mobile conditions. A novel visual tracking approach is proposed to address this issue by establishing a shape beacon at the OWC terminals. The shape beacon can be sensed from virtually all directions with a camera; hence, visual tracking is an acceptable ATP solution for mobile OWCs. Results of numeric analysis indicate that visual tracking is suitable for mobile OWCs as well as conventional OWCs with acceptable accuracy. Experiments were performed to demonstrate the visual tracking procedures using the vehicle itself as the shape beacon.A dynamic pulse propagation modeling for femtosecond laser bonding of Borofloat glass is presented. The temperature evolution and internal modifications are predicted by incorporating the nonlinear electron dynamics along with temperature dependent thermal properties. The modelling predicts the spatial and temporal distribution of absorption coefficient and plasma density that gives quantitative estimations of the heat affected zone and weld geometry. The impact of focusing condition on heat affected zone and weld geometry is investigated, which for the first time to our knowledge allows to numerically determine the desired relative position between the geometrical focus of a femtosecond-laser-pulse and the interface of the two substrates to be welded. The prediction of the modelling on the offset distance is applied to weld Borofloat glass plates having optical contact and can be applied to other dielectric solids.Photosensitivity in photo-thermo-refractive (PTR) glass can be triggered by UV and near-infrared fs laser irradiation. Here we focus on the nonlinear photochemical process triggered by ultrashort laser Gaussian-Bessel beams. The transmission and absorption spectra show that the primary difference between UV and fs laser exposure is the formation of color centers and kinetic process of silver nanoparticles growth. It is contributed to the nonlinear ionization of PTR glass matrix and thermal effects during interaction of glass matrix and ultrashort laser pulses. https://www.selleckchem.com/products/crenolanib-cp-868596.html Transmission electron microscopy verifies the generation of nanoscale crystals in the irradiated region, and X-ray diffraction shows the existence of quartz crystal and NaF after laser irradiation and thermal treatment. Moreover, the dependence of photochemical reaction on laser parameters is investigated, as well as the tailoring of silver nanoparticles. On this basis, volume Bragg gratings with ultrashort laser Gaussian-Bessel beams are inscribed as an application which possess good diffraction characteristics.We show that narrowband two-color entangled single Stokes photons can be generated in a ultra-cold atoms sample via selective excitation of two spontaneous four-wave mixing (SFWM) processes. Under certain circumstances, the generation, heralded by the respective common anti-Stokes photon, is robust against losses and phase-mismatching and is remarkably efficient owing to balanced resonant enhancement of the two four-wave mixing processes in a regime of combined induced transparency. Maximally color-entangled states can be easily attained by adjusting the detunings of the external couplings and driving fields, even when these are quite weak.Traditional cameras are limited by sensors and cannot directly capture single-shot high dynamic range (HDR) images. We propose an improved single-shot HDR image reconstruction method that uses a single-exposure filtered low dynamic range (FLDR) image. First, by adding an optical filter in front of the camera lens, a FLDR image with different RGB channel exposure states and luminance ranges can be captured in a single-shot, unlike the traditional LDR image. Second, a deep inverse tone mapping network (DITMnet) with multibranch features extraction and multioutput images synthesis is designed to reconstruct an HDR image from a single FLDR image. Experimentally, under different exposure states and color spaces, our method outperforms similar algorithms.Structured lights, particularly those with tunable and controllable geometries, are highly topical due to a myriad of their applications from imaging to communications. Ray-wave duality (RWD) is an exotic physical effect in structured light that the behavior of light can be described by both the geometric ray-like trajectory and a coherent wave-packet, thus providing versatile degrees of freedom (DoFs) to tailor more general structures. However, the generation of RWD geometric modes requires a solid-state laser cavity with strict mechanical control to fulfill the ray oscillation condition, which limits the flexiblility of applications. Here we overcome this confinement to generate on-demand RWD geometric modes by digital holographic method in free space without a cavity. We put forward a theory of generalized ray-wave duality, describing all previous geometric modes as well as new classes of RWD geometric modes that cannot be generated from laser cavities, which are verified by our free-of-cavity creation method.
It also benefits the development of autofocusing 3D measurement technology.The direct pickup of integral imaging typically needs to overcome limitations especially the restricted depth of field (DoF) under a lenslet array. In order to solve the problem, we design a motion parallax enhancing approach for three-dimensional (3-D) integral optical display only relying on a commercial Lytro camera. First, the non-uniform axial compression from the zoom lens of the Lytro camera is analyzed and experimentally investigated. Next, using depth slicing, locating and retargeting, the parallax of the integral optical display is significantly enhanced. Additionally, the displayed depth information can be presented in a uniform compression with the same proportion as the real scene even without the prior knowledge of the actual object distance. The experimental results prove the feasibility of the proposed method, which provides an efficient way for the acquisition of the elemental image array. Additionally, it is also a new attempt to expand the application scope of the Lytro camera from 2-D refocusing to the content acquisition for the integral display.Acquisition, tracking, and pointing (ATP) mechanisms are generally adopted for optical wireless communications (OWCs) to maintain a strict alignment state for reliable communication. ATP mechanisms conventionally employ beacon lights to determine the orientation of the remote optical terminal. They typically cannot maintain a steady alignment under mobile conditions. A novel visual tracking approach is proposed to address this issue by establishing a shape beacon at the OWC terminals. The shape beacon can be sensed from virtually all directions with a camera; hence, visual tracking is an acceptable ATP solution for mobile OWCs. Results of numeric analysis indicate that visual tracking is suitable for mobile OWCs as well as conventional OWCs with acceptable accuracy. Experiments were performed to demonstrate the visual tracking procedures using the vehicle itself as the shape beacon.A dynamic pulse propagation modeling for femtosecond laser bonding of Borofloat glass is presented. The temperature evolution and internal modifications are predicted by incorporating the nonlinear electron dynamics along with temperature dependent thermal properties. The modelling predicts the spatial and temporal distribution of absorption coefficient and plasma density that gives quantitative estimations of the heat affected zone and weld geometry. The impact of focusing condition on heat affected zone and weld geometry is investigated, which for the first time to our knowledge allows to numerically determine the desired relative position between the geometrical focus of a femtosecond-laser-pulse and the interface of the two substrates to be welded. The prediction of the modelling on the offset distance is applied to weld Borofloat glass plates having optical contact and can be applied to other dielectric solids.Photosensitivity in photo-thermo-refractive (PTR) glass can be triggered by UV and near-infrared fs laser irradiation. Here we focus on the nonlinear photochemical process triggered by ultrashort laser Gaussian-Bessel beams. The transmission and absorption spectra show that the primary difference between UV and fs laser exposure is the formation of color centers and kinetic process of silver nanoparticles growth. It is contributed to the nonlinear ionization of PTR glass matrix and thermal effects during interaction of glass matrix and ultrashort laser pulses. https://www.selleckchem.com/products/crenolanib-cp-868596.html Transmission electron microscopy verifies the generation of nanoscale crystals in the irradiated region, and X-ray diffraction shows the existence of quartz crystal and NaF after laser irradiation and thermal treatment. Moreover, the dependence of photochemical reaction on laser parameters is investigated, as well as the tailoring of silver nanoparticles. On this basis, volume Bragg gratings with ultrashort laser Gaussian-Bessel beams are inscribed as an application which possess good diffraction characteristics.We show that narrowband two-color entangled single Stokes photons can be generated in a ultra-cold atoms sample via selective excitation of two spontaneous four-wave mixing (SFWM) processes. Under certain circumstances, the generation, heralded by the respective common anti-Stokes photon, is robust against losses and phase-mismatching and is remarkably efficient owing to balanced resonant enhancement of the two four-wave mixing processes in a regime of combined induced transparency. Maximally color-entangled states can be easily attained by adjusting the detunings of the external couplings and driving fields, even when these are quite weak.Traditional cameras are limited by sensors and cannot directly capture single-shot high dynamic range (HDR) images. We propose an improved single-shot HDR image reconstruction method that uses a single-exposure filtered low dynamic range (FLDR) image. First, by adding an optical filter in front of the camera lens, a FLDR image with different RGB channel exposure states and luminance ranges can be captured in a single-shot, unlike the traditional LDR image. Second, a deep inverse tone mapping network (DITMnet) with multibranch features extraction and multioutput images synthesis is designed to reconstruct an HDR image from a single FLDR image. Experimentally, under different exposure states and color spaces, our method outperforms similar algorithms.Structured lights, particularly those with tunable and controllable geometries, are highly topical due to a myriad of their applications from imaging to communications. Ray-wave duality (RWD) is an exotic physical effect in structured light that the behavior of light can be described by both the geometric ray-like trajectory and a coherent wave-packet, thus providing versatile degrees of freedom (DoFs) to tailor more general structures. However, the generation of RWD geometric modes requires a solid-state laser cavity with strict mechanical control to fulfill the ray oscillation condition, which limits the flexiblility of applications. Here we overcome this confinement to generate on-demand RWD geometric modes by digital holographic method in free space without a cavity. We put forward a theory of generalized ray-wave duality, describing all previous geometric modes as well as new classes of RWD geometric modes that cannot be generated from laser cavities, which are verified by our free-of-cavity creation method.
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