Bjerrumgutierrez9695

We present a method for evaluating the quality of optical glass using a high-resolution wavefront sensor, the wavefront phase imaging (WFPI) sensor. As shadowgraphy is a widely used method for inspecting striae in optical glass, it does not provide a quantitative metric that represents the potential optical quality of the glass and should be based on the operator's experience. We compare the proposed method in two experiments. First, we compare it with the results obtained by shadowgraphy on a variety of samples. Second, we compare the results of a single-point chromatic confocal profilometer on a calibrated sample. The WFPI shows results comparable to the reference method in both cases but provides more information than shadowgraphy and avoids the human factor in the measurement.A ring focus reflector is proposed for transmitting a perfect vortex (PV) beam, and the transmission characteristics of the PV beam with different topological charges in free space after passing through the reflector are studied. The reflector parameters can be determined by fitting the structural formula, and PV beams of different orders transmit with small spot sizes at the same time. The transmission trajectory calculated by the diffraction formula is consistent with the ray tracing results. The research results show that the reflector can achieve a high level of transmission efficiency of beams with different topological charges, which is conducive to the multiplexing of PV beams.The measurement of low-frequency vibration signals is of great significance in seismic monitoring, health monitoring of large and medium-sized engineering structures, and resource exploration. In view of the low sensitivity of fiber Bragg grating (FBG) acceleration sensors in measuring low-frequency vibration signals, a high-sensitivity, low-frequency dual-FBG acceleration sensor is proposed. Theoretical formula derivation and ANSYS software were used to optimize the design and simulation analysis of the structural parameters of the sensor. The real sensor was made based on the simulation results, and a test system was established to test its performance. According to the findings, the natural frequency of the acceleration sensor is 65 Hz. It gives a flat sensitivity response in the low frequency band of 3-45 Hz. The dynamic range is 92.63 dB at 10 Hz, the acceleration sensitivity is 1498.29 pm/g, and the linearity R2 is 0.9998. The relative standard deviation of the sensor repeatability is 1.75%, and the transverse crosstalk in the working frequency band is -33.99dB. Designed with a high sensitivity and excellent temperature compensation capacity in the low-frequency band, the designed sensor is suitable for low- and medium-frequency vibration detection in engineering.Accurate detection technology of the microwave electric field is an important foundation to explore new materials, devices, and electromagnetic effects. In this paper, the design of a microwave electric field detection enhanced by a resonant cavity was proposed and experimentally verified. The simulation results show that the enhancement factor is 3.45 at the position of 3 mm from the square SRR). Adenine sulfate clinical trial By combining the experimental system, the actual enhancement factor is 3.31(6), and the corresponding electric field detection sensitivity is increased from 1.02 V/m to 0.30 V/m. The proposed scheme provides certain technical support for the weak microwave electric field detection and the development of the integrated atomic microwave detection unit.Electro-optic (EO) modulators based on polymer-embedded silicon racetrack resonators (EOM-PSRR) are investigated. To obtain the single-mode propagation condition, the mode and transmission characteristics of the polymer-embedded silicon waveguide are simulated by the finite element method (FEM). By adding a static bias voltage, the EO modulation performances of EOM-PSRR embedded with lithium niobate (LiNbO3), EO polymer (AJ309), and hybrid EO polymer/TiO2 material (HEOT) are studied. The results show that the EOM-PSRR embedded with LiNbO3 achieves a high modulation depth (MD) of ∼27.6dB with a low EO wavelength tuning (λEO) of 10 pm/V. However, the EOM-PSRR embedded with HEOT has a high λEO of 100 pm/V but a low MD of ∼6.2dB with an extinction ratio of ∼5.2dB. The EOM-PSRR has potential application prospects in optical communication, optical signal processing, and optical network links. It can be produced as an optical frequency comb generator in a dense wavelength division multiplexing system, an EO frequency shifter for laser beams, an optical soliton former, and a photon time-delay device in a phased array radar.In an uncooled infrared imaging system, thermal radiation effects are caused by the heat source from the target or the detection window, which affects the ability of target detection, tracking, and recognition seriously. To address this problem, a multi-scale correction method via a fast surface fitting with Chebyshev polynomials is proposed. A high-precision Chebyshev polynomial surface fitting is introduced into thermal radiation bias field estimation for the first time, to the best of our knowledge. The surface fitting in the gradient domain is added to the thermal radiation effects correction model as a regularization term, which overcomes the ill-posed matrix problem of high-order bivariate polynomials surface fitting, and achieves higher accuracy under the same order. Additionally, a multi-scale iterative strategy and vector representation are adopted to speed up the iterative optimization and surface fitting, respectively. Vector representation greatly reduces the number of basis function calls and achieves fast surface fitting. In addition, split Bregman optimization is used to solve the minimization problem of the correction model, which decomposes the multivariable optimization problem into multiple univariate optimization sub-problems. The experimental results of simulated and real degraded images demonstrate that our proposed method performs favorably against the state of the art in thermal radiation effects correction.Liquid crystal variable retarders (LCVRs) are the core component for rapid and high-precision broadband polarization detection. Additionally, the ability to suppress noise greatly affects the results of polarization measurements. In this work, a solving optimal design approach is proposed for building a high-performance broadband Stokes polarimeter based on LCVRs, which greatly reduces the influences of data fluctuation from liquid crystals and dispersion on the experimental results. This method relies on evaluation criteria of the condition number (CN) to build a gradual optimization that includes the following three steps fixing the fast axis angles, meeting the requirements of a wideband, and ensuring a minimum CN. Additionally, with the method of increasing the measurement analysis vector, we ensure the whole band in the low CN and offer a solution to the problem of the difficulty in optimizing the LCVRs caused by the large change of retardance at 490-700 nm. Finally, the rapid and high-precision Stokes measurement of 490-700 nm wavelengths is achieved. We test the performance of the polarimeter after optimization in our simulation and experiment, which shows that the total RMS error is less than 0.032 and the single point error is small. This work not only reduces the influence of LCVR error on the experimental results but also makes it possible to apply LCVRs to 490-700 nm detection.In this paper, we propose, to the best of our knowledge, a novel method of simultaneously detecting and evaluating the location and size of particles from a compression particle interferogram. The 2D position of the particle can be determined with high accuracy, as evaluated by the unidirectional gradient-match with the conjoint to centroid method. The fast-Rife method provides sub-pixel accuracy and high speed for estimating the fringe frequency from the Fourier spectrum of a particle interferogram. The capability mentioned above is well verified using synthetic and experimental data. The computational load falls almost 50%, and the relative error of the measured particle diameter is less than 1.12% for homogeneous solutions of polystyrene spheres of 50 µm and 70 µm. The results demonstrate that the method presented here is considerably promising for its application to a high-density particle field, such as spray, in accurately measuring both the particle size and its location.In the field of digital holography, the speckle caused by coherent light greatly disturbs the quality of the reconstruction. This paper presents an innovative method to efficiently reduce speckle noise with a nonlocal means filter based on cosine similarity that determines the weight of each traversal pixel to the target pixel by comparing the similarity between the target pixel neighborhood and the traversal pixel neighborhood. Experimental results with qualitative and quantitative analysis indicate that the proposed method significantly improves noise reduction performance while preserving the details of the original image. Compared with other general image-processing methods, this well-directed method is more in line with the characteristics of holographic speckle noise and has obvious advantages in various metrics.Surface plasmon polaritons (SPPs) are traditionally excited by plane waves within the Rayleigh range of a focused transverse-magnetic (TM) Gaussian beam. Here we investigate and confirm the coupling between SPPs and two-dimensional Gaussian and Bessel-Gauss wave packets, as well as one-dimensional light sheets and space-time wave packets. We encode the incoming wavefronts with spatially varying states of polarization; then we couple the respective TM components of radial and azimuthal vector beam profiles to confirm polarization-correlation and spatial-mode selectivity. Our results do not require material optimization or multi-dimensional confinement via periodically corrugated metal surfaces to achieve coupling at a greater extent, hereby outlining a pivotal, yet commonly overlooked, path towards the development of long-range biosensors and all-optical integrated plasmonic circuits.A narrow-band transmission filter based on one-dimensional photonic crystals with SiO2/titaniumdioxide(TiO2) layers is grown by sol-gel spin-coating processing. The structural and optical properties of fabricated samples are characterized by an atomic force microscope, scanning electron microscope, and UV-visible spectroscopy. Specific wavelength transmission and bandgap in the optical filter with and without a defect layer have been investigated by engineering the layer thickness and defect layer material. For three fabricated optical filters, it is found that the maximum transmission for the TiO2 and InP defect layers reaches 58.09% and 42.21%, respectively. The layer thickness is fixed just by tuning the rotational speed of the spin-coater.Rainbow refractometry was used to measure the temperature and size of transparent spherical particles. In practice, however, there are limitations to the application of heating and cooling droplets, as the temperature measured is neither the average nor the surface or core temperature of the droplet. Reported here is an exploitation of this technique for droplet surface temperature determination. Droplet surface tension was measured by detecting the evolution of interference fringes of oscillating droplets. The dependence of surface tension on temperature facilitated the study of surface temperature of an evaporating droplet with time. Moving ethanol, n-heptane, and n-decane droplets were investigated under heating and cooling conditions. The capabilities and limitations of rainbow refractometry were verified by comparing the droplet temperature values measured directly by rainbow refractometry with the surface temperature.