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079. The results indicated that the LIBS technique coupled with LS-SVR could be a reliable and accurate method for determining pH value in soil.Optimization of a wide-angle paratellurite acousto-optic tunable filter (AOTF) is performed for applications in laser beam shaping systems. The AOTF configuration with annular transfer function is analyzed. It is demonstrated that the optimal AOTF design for single-frequency operation as a narrow-band spatial frequency filter is obtained at acoustic propagation angle of 5.6° relative to the [110] axis. The optimal design for maximization of AOTF resolution in multifrequency laser beam shaping operation mode is obtained at acoustic propagation angle of 13.8°.We investigated interference fringes due to superposition of diverging light waves reflected from the two sides of a plane parallel plate. A non-localized fringe pattern of high contrast was obtained as a function of incident angle when we used a coherent diverging beam. We found that the fringe density increased to a certain angle and then decreased thereafter, against the common belief that the fringe density increases monotonically with the angle of incidence. Because the fringe density is maximum at this angle and does not change rapidly in the vicinity, we could employ Fourier analysis to estimate interferometric parameters, such as thickness, refractive index, and wavelength, that determine the characteristic stationary fringe density.The promising advancement of supercontinuum generation in optical fibers has initiated significant interest in recent research studies and several continuing applications. We numerically corroborate the effects of picosecond pulse pumped supercontinuum (SC) by using two weak continuous-wave (CW) triggers with 1% pump intensity. Compared with SC with one CW trigger, adding two CW triggers (1% pump power), both near the modulation instability peaks, can achieve wider spectra for a picosecond pulse pumped SC. Furthermore, good coherence properties may be achieved in the wavelength range from 1300-2000 nm when one CW trigger is near the pump center wavelength and the other CW trigger is distant from the pump. In our simulations, putting two CW triggers on the same side (concerning the pump wavelength) or putting them on different sides have similar effects on SC spectral and temporal coherence properties. Therefore, by engineering the wavelengths of two CW triggers to offer better bandwidth or coherence, we envision that the proposed technique could play a significant role in the generation of SC.Visible light communication is a kind of wireless communication that combines illumination and communication, so dimming control is an essential function for visible light communication systems. Although many dimming control schemes have been proposed, few simultaneously utilize amplitude and spatial resources. The combination of these two resources can further improve the communication performance of the system. Thus, we propose a dimming control scheme that takes advantage of phase-shifted space-time codes to improve error performance and spectral efficiency. Additionally, we provide an encoding structure and a fast detection algorithm for the proposed scheme. Finally, simulation results show the performance of the proposed scheme compared with other schemes.Digital holographic microscopy (DHM) suffers from a limited refocus depth range due to the employed microscope objective. The relationship between the refocus depth range of the DHM system and its optical parameters is studied theoretically and experimentally, and a method is proposed that combines wavefront coding with bicubic interpolation and extrapolation iteration to extend the refocus depth range. For obtaining a uniform point spread function on the refocus plane, a propagator kernel in numerical reconstruction is multiplied by a numerical logarithmic phase mask, and a deviation of the refocus distance is made. To improve the resolution of the refocused image, the size of the hologram is doubly enlarged. This approach can extend the refocus depth range from 0.9 up to 1.5 mm. This work provides important guidance for high-resolution imaging with a large refocus depth range in DHM.This paper proposes a framework for the three-dimensional (3D) reconstruction of specular surfaces. The framework begins with a modified reconstruction method that uses gradient descent to accurately search for the correspondence matches in the binocular vision system. An analysis of the binocular vision system shows that the reconstruction result is not necessarily unique and the reconstruction accuracy is significantly compromised by a bilinear interpolation error. An error-based selection algorithm is proposed to select the correct result. To improve the reconstruction accuracy, binocular vision and zonal wavefront reconstruction are incorporated. The reconstruction result from the binocular vision system is taken as a reference surface for slope estimation. The measured slope is then integrated into a height map by the zonal wavefront reconstruction. The overall reconstruction process provides an accurate reconstruction result without the need for prior surface information. Simulations and experiments were conducted to verify the feasibility of the proposed algorithms. A relative error of 0.59% or less is experimentally recorded in the step-size measurement of a stair-like object.Hollow-core fibers are advantageous for chemical sensing as they facilitate liquid infiltration into the core over conventional porous core fiber. In addition, the requirement of less bulk material significantly decreases the effective material loss (EML). check details In this paper, a six circular cladding tube negative curvature hollow-core fiber (NC-HCF) is proposed for chemical sensing. Five different chemicals including chloroform, polylactic acid, CCL3, glycerin, and benzene are proposed to fill the core of the NC-HCF, and sensitivities are evaluated by full vector finite element method-based COMSOL software. Numerical results reveal that the proposed sensor exhibits very high relative sensitivity in a wide range of frequency. The fabrication of the proposed fiber is feasible by existing fabrication facilities as it contains realistic fabrication parameters. Hence, the proposed sensor can potentially be used as a chemical sensor especially in the medical, food, and industrial sectors as the five chemicals mentioned above carry great medical and food significance.