Valentinlott8587

For the current problems of extremely complex visible light indoor positioning algorithms and devices and low positioning accuracy, this paper proposes an improved indoor positioning method combining light-emitting diode (LED) visible light and quick response (QR) codes. First, initial positioning is achieved by loading a QR code image containing LED position information on the LED light, which is recognized and decoded by the receiver. Then the position of the receiver is precisely located by proposing an improved indoor positioning method. The experiment shows the smallest average error of 4.0326 cm in positioning, which greatly improves the indoor positioning accuracy.Chirality has always been a hot research topic because it possesses potential applications in polarization optics, chemical and biosensing. In the previous works, intrinsic chirality has been extensively explored, but its development is limited due to the complexity in fabrication of chiral metamaterials. Therefore, there is an urgent need to simplify fabrication and design of compact devices with chiral response. Extrinsic chirality has shown great potential because it can be realized in nonchiral anisotropic planar structures with low-cost fabrication techniques. In this paper, the extrinsic chirality of biaxial hyperbolic material $\alpha \text -\rmMo\rmO_3$ with in-plane anisotropy has been investigated. By analyzing the effect of thickness of $\alpha \text -\rmMo\rmO_3$ film, the angle of incidence, azimuth angle, and wavelength of incidence on the circular dichroism (CD), the maximum CD can reach 0.77. This strong extrinsic chirality of the $\alpha \text -\rmMo\rmO_3$ film results from the mutual orientation of the $\alpha \text -\rmMo\rmO_3$ film and the incident light. In addition, $\alpha \text -\rmMo\rmO_3$ film can still maintain strong extrinsic chirality when the azimuthal angle ranges from approximately 20°-57° and the angle of incidence is from 55°-80°.Computational ghost imaging is difficult to apply under low sampling rate. We propose high-speed computational ghost imaging based on an auto-encoder network to reconstruct images with high quality under low sampling rate. The auto-encoder convolutional neural network is designed, and the object images can be reconstructed accurately without labeled images. Experimental results show that our method can greatly improve the peak signal-to-noise ratio and structural similarity of the test samples, which are up to 18 and 0.7, respectively, under low sampling rate. Our method only needs 1/10 of traditional deep learning samples to achieve fast and high-quality image reconstruction, and the network also has a certain generalization to the gray-scale images.The characteristics of laser-induced underwater acoustic signals (UASs) generated by focused 10 ns and 30 ps laser pulses of different energies under similar experimental conditions are compared. Time domain signals and time-frequency analysis of the UASs were used to understand the role of input pulse duration and energy on the evolution of UAS. In the time domain, the peak-to-peak ($\rm P_k - \rm P_k$) overpressure of the UAS decreases, and the arrival time ($\rm A_t$) increases as a function of propagation distance for both ns and ps laser-induced breakdown (LIB) of water. HS173 With increasing incident energy of both ns and ps laser pulses, the $\rm P_k - \rm P_k$ overpressures of acoustic signals increase almost linearly. In the time-frequency domain, the spectrogram obtained via short-time Fourier transform provides spectral information and $\rm A_t$ of both direct and reflected signals simultaneously. The spectrogram revealed that the transient UAS has broad acoustic spectra spanning from 10 to 800 kHz, perpendicular to the laser propagation direction. The initial acoustic impulse resulted in two major frequencies centered around 105 and 690 kHz with a standard error of 30 kHz. Upon reflection from the water-air interface, only the peak frequency corresponding to $\sim105\;\rm kHz$ was reflected, while the longer frequency was observed to dissipate. Our results demonstrate that the ns-LIB is more suitable for applications compared to the ps-LIB owing to stronger acoustic impulse of both direct and reflected signals.A study on the influence of multiple reflections on the transmission coefficients of uniaxial plane-parallel plates is presented. Two representative models are analyzed one that considers only the first transmission, and a rigorous one, taking into account the multiple reflections within the plate. Modules, phases, and the interference between $p$ and $s$ transmitted fields are evaluated in a wide range of angles of incidence by means of three emblematic examples that illustrate the effects of thickness, birefringence, and optical axis orientation. For simplicity, whereas the optical axis can form an arbitrary angle with the interface, it is restricted to the plane of incidence. A complete theoretical framework is provided along with general reference guidelines derived from numerical examples.With the development of plasmonic optical waveguides, numerous nanostructures based on different materials can be fabricated in a controlled way. While doing reversible computing, reversible logic gates are the necessary requirement to reduce the loss of information with less power consumption. The proposed design of the Feynman logic gate is simulated by a cascading metal-insulator-metal optical waveguide based on Mach-Zehnder interferometers. The footprint of the proposed Feynman logic gate is $62\;\unicodex00B5\rm m \times 9\;\unicodex00B5\rm m$, the extinction ratio is 10.57 dB, and the insertion loss is $-0.969\;\rm dB$ and $-1.191\;\rm dB$, which is much better compared to an electro-optic-based exiting Feynman logic gate. The results are obtained by simulating the proposed structure using the finite difference time domain method and verified by using mathematical computation in MATLAB.This paper proposes a design method for an off-axis reflective anamorphic optical system (ORAOS). This method first applies vector aberration theory to establish a mathematical model to balance the aberration of an ORAOS. It then builds the error function of structural parameters and constraints through spatial ray tracing and grouping design. Next, it introduces automatic adjustment of weight factors for dynamic balance of aberrations and constraints. A particle swarm simulated annealing algorithm is used to iteratively calculate the initial structure of the ORAOS. Finally, we use an extreme ultraviolet (EUV) lithographic projection objective with off-axis six-reflective anamorphic mirrors ($\beta _x = 1/4,\beta _y = 1/8$) as an example to verify the effectiveness of this method. We obtain an EUV lithographic anamorphic objective with a numerical aperture of 0.55 and a root mean square wavefront error better than $1/30\lambda$ ($\hat\text I\gg\, = 13.5\;\rm nm$).These days when integrated circuit (IC) designers are facing an uphill task in limiting energy/heat dissipation, reversible computing is emerging as a potential candidate with vast application in fields like nanotechnology, quantum-dot cellular automata, and low power IC. Optical reversible logics have turned up to offer high speed and low energy computations with almost no loss of input information when a certain (arithmetic or logical) operation is performed. This paper explores an optical implementation of an optimized Fredkin gate that is employed to design an $ N2^N $ reversible decoder. The optical designs have been carried out using the electro-optic effect of a lithium niobate ($ \rm LiNbO_3$)-based Mach-Zehnder interferometer under the beam propagation method (BPM) with Optiwave's OptiBPM tool. The mathematical model of output power of these designs is also performed along with its validation in MATLAB.Optical path difference (OPD) is a very significant parameter in the asymmetric common-path coherent-dispersion spectrometer (CODES), which directly determines the performance of the CODES. In order to improve the performance of the instrument as much as possible, a temperature-compensated optimal optical path difference (TOOPD) method is proposed. The method does not only consider the influence of temperature change on the OPD but also effectively solves the problem that the optimal OPD cannot be obtained simultaneously at different wavelengths. Taking the spectral line with a Gaussian-type power spectral density distribution as a representative, the relational expression between the OPD and the visibility of interference fringes formed by the CODES is derived for the stellar absorption/emission line. Further, the optimal OPD is deduced according to the efficiency function, and the relationship between the optimal OPD and wavelength is analyzed. Then, based on the materials' dispersion characteristics, diffeability of the whole spectrometer. Hence, the TOOPD method provides a new idea for further improving the high-precision radial velocity detection of the asymmetric common-path CODES.This work presents a high-speed, spectrally resolved, mid-infrared imaging diagnostic for providing 1D measurements of gas temperature and relative mole fraction of $\rmCO_2$ and HCl in flames. An imaging spectrometer and a high-speed mid-infrared camera were used to provide 1D measurements of $\rmCO_2$ and HCl emission spectra from 2386 to $2402\;\rmcm^- 1$ with a spectral resolution of $0.46\;\rmcm^- 1$, and simulated emission spectra were least-squares fit to the data to determine the aforementioned gas properties. Measurements were acquired in HMX and AP-HTPB flames burning in air at 1 atm. This diagnostic was applied to characterize how the path-integrated gas temperature of HMX flames varies in time and with distance above the burning surface. Additionally, Abel inversion with Tikhonov regularization was applied to determine the radial distribution of temperature and relative concentration of $\rmCO_2$ and HCl within the core of AP-HTPB flames. The results demonstrate that this diagnostic has potential to further our understanding of propellant combustion physics by quantifying thermochemical flame structure at rates up to 2 kHz.We demonstrate a method to double the collection efficiency in laser tweezers Raman spectroscopy (LTRS) by collecting both the forward-scattered and backscattered light in a single-shot multitrack measurement. Our method can collect signals at different sample volumes, granting both the pinpoint spatial selectivity of confocal Raman spectroscopy and the bulk sensitivity of non-confocal Raman spectroscopy simultaneously. Further, we display that our approach allows for reduced detector integration time and laser power. To show this, we measure the Raman spectra of both polystyrene beads and bacterial spores. For spores, we can trap them at 2.5 mW laser power and acquire a high signal-to-noise ratio power spectrum of the calcium-dipicolinic acid peaks using an integration time of $2 \times 30\;\rm s$. Thus, our method will enable the monitoring of biological samples sensitive to high intensities for longer times. Additionally, we demonstrate that by a simple modification, we can add polarization sensitivity and retrieve extra biochemical information.