Optical Testing Research Articles

Analisa Hasil Sambungan Las ( Pipa STKM 13B Dan Plat SPH 440) Dengan Pengujian Tarik dan Photomacro

ABSTRACTGMAW (Gas Metal Arc Welding) is a fast, versatile welding technique that can be used in various positions, but it often results porosity in welded joints.This research aims to analysis of the welded joints of STKM13B pipe and SPD 440 plate using tensile and micro testing, using welding a current of 18 and varying voltages of 110, 130, and 150. The results is the shape of the welded joint of the plate and pipe is perfectly connected, the tensile test results showed that the ultimate strength values for specimen 1, 2, 3 (A110/V18, A130/V18, A150/V18) were (18,959, 27,886, 40,005 N) respectively. The highest ultimate strength values were obtained from the specimens (A150/V18) while the lowest ultimate strength value was obtained from specimen (A110/V18). The use of welding current strongly correlates with ultimate strength value and photomacro results, with higher currents resulting in higher density levels, minimizing porosity, and increasing ultimate strength. Keywords: GMAW Welding, Tensile Test, Macro Optical Test.

Integrating eye rotation and contrast sensitivity into image quality evaluation of virtual reality head-mounted displays

Visual perception on virtual reality head-mounted displays (VR HMDs) involves human vision in the imaging pipeline. Image quality evaluation of VR HMDs may need to be expanded from optical bench testing by incorporating human visual perception. In this study, we implement a 5-degree-of-freedom (5DoF) experimental setup that simulates the human eye geometry and rotation mechanism. Optical modulation transfer function (MTF) measurements are performed using various camera rotation configurations namely pupil rotation, eye rotation, and eye rotation with angle kappa of the human visual system. The measured MTFs of the VR HMD are inserted into a human eye contrast sensitivity model to predict the perceptual contrast sensitivity function (CSF) on a VR HMD. At the same time, we develop a WebXR test platform to perform human observer experiments. Monocular CSFs of human subjects with different interpupillary distance (IPD) are extracted and compared with those calculated from optical MTF measurements. The result shows that image quality, measured as MTF and CSF, degrades at the periphery of display field of view, especially for subjects with an IPD different than that of the HMD. We observed that both the shift of visual point on the HMD eyepiece and the angle between the optical axes of the eye and eyepiece degrade image quality due to optical aberration. The computed CSFs from optical measurement correlates with those of the human observer experiment, with the optimal correlation achieved using the eye rotation with angle kappa setup. The finding demonstrates that more precise image quality assessment can be achieved by integrating eye rotation and human eye contrast sensitivity into optical bench testing.

First light simultaneous triple-channel optical observations of the OPTICAM system at the OAN-SPM

OPTICAM is a triple-band optical system developed for the 2.1 m telescope of the National Astronomical Observatory in the Sierra de San Pedro Mártir (OAN-SPM). Partial engineering tests were conducted in 2019, with the complete system experiencing its first light in March 2022. The system incorporates two beam splitters, enabling simultaneous observations on three channels. Users can choose three out of the five available filters from the SDSS filter set (u′g′r′i′z′), covering the wavelength range from 320 to 1000 nm. It offers an effective field of view of approximately 4.7, 4.7, and 5.6 arcminutes in each of its arms, respectively. Due to its design and capabilities, OPTICAM is suitable for coordinated observations with other ground-based and space-based observatories. This document presents the final instrument design and the current system status. Some of the optical tests carried out are described. We also present the results of scientific observations conducted during its first light and first year of operations.

Rheological aspects of solid-to-liquid phase transitions in paraffin wax/bitumen blends for thermal energy storage applications

This paper correlates the evolution of the rheological and thermal properties with microstructure during the phase change of a blend of bitumen with a selected paraffin wax, having a melting point centred around 60 °C, for the development of bituminous based membranes for thermal energy storage applications. For this purpose, temperature sweep tests within the linear viscoelastic range, stationary state flow curves, Differential Scanning Calorimetry (DSC), polarised optical microscopy observations and solar irradiation tests were performed. The reported rheological results clearly point out a gel-like behaviour for both paraffin and paraffin/bitumen blend that is preserved almost up to the end of the phase change interval. This is consequence of the development of a network of interconnected crystals of paraffin wax which progressively disappear as temperature increases. Interestingly, a weak gel structure is kept even at low crystallinity levels since only a few junctions among structures are necessary to build a spanning network. Finally, the large degree of crystallinity of paraffin wax retained in the bitumen/paraffin wax is behind its thermoregulation ability, as was corroborated by solar irradiation tests. Therefore, results indicated the great potential of these formulations for thermal energy storage and related applications.

Tailoring the physical, optical, and structural properties of bismuth oxide to enhance its anionic, cationic, and phenol dye degradation activities

We provide a novel investigation that demonstrates the synthesis of silver-doped bismuth oxide (ABO), holmium-doped bismuth oxide (HBO), nanostructured bismuth oxide (BO), and silver-holmium co-doped bismuth oxide (CDBO) by a cost-effective and straightforward surfactant-assisted co-precipitation technique. In comparison to the BO, ABO, and HBO samples, the optical tests revealed that the CDBO sample exhibited superior photocatalytic characteristics. This is possibly attributed to the physical, optical, and structural properties of the material tailored by the synergistic effect of the adopted strategies, i.e., nanotechnology, oxygen vacancies, and co-doping. The microstructures, physicochemical properties, morphological characteristics, and compositional attributes of the synthesized materials were investigated using sophisticated characterization techniques. The intrinsic conductivity of the bismuth oxide was enhanced with the incorporation of Ag and Ho as co-dopants, as shown by the results obtained from two probe current-voltage experiments. The co-doped sample exhibited the highest efficacy in decomposing rhodamine B dye, with a degradation rate of 91 % during a mere 70-min exposure to W-lamp illumination. The most ideal settings for CDBO photocatalytic activities were identified by comprehensive parameter optimization research. These parameters include a basic pH, a catalyst dosage of 25 mg, a dye concentration of 15 ppm, and an operating temperature of 30 °C. The co-doped and nanostructured photocatalyst also showed an outstanding capability to break down orange II and phenol dye. The trapping experiments' results indicate that the hydroxyl and superoxide radicals play a significant role in the mineralization of the tested dye.

Effect of the silanization process on the fire resistance and thermal properties of closed-cell foams with sunflower husk ash

The topics covered in this paper are relevant to the further development of polyurethane materials and propose a new method for producing sustainable and innovative foams. In this study, the effect of filler silanization on the flammability and thermal stability of rigid polyurethane foam (RPUF) was investigated. The RPUF composites study was preceded by an analysis of sunflower husk ash (SHA). Thermal decomposition behaviour and particle size distribution were carried out for the SHA samples. More, the elemental composition and structure of the fillers were investigated. The use of silanization of the filler results in homogenization of its structure. Sunflower husk ash has higher characteristic melting points than most biomass ashes and good thermal stability. The foam flammability results were preceded by an analysis of density and cell morphology. The use of silanized filler in RPUFs results in a homogenized structure and a 14 % reduction in apparent density. A wide range of tests were carried out as part of the flammability tests, which included: limiting oxygen index (LOI), gross calorific value, cone calorimeter, and optical density test. Additionally, thermal analysis methods were used to investigate the thermal stability of the foams. Flammability tests carried out confirm the positive effect of filler salinization on flammability. Heat release during combustion is reduced by 10 % and the release of toxic gases is also reduced. On the other hand, the thermal stability results are similar for foam with unmodified filler and those with silanized ash. Based on the comprehensive flammability and smoke results, a trend towards improved flame-retardant properties of RPUFs was observed.

Advancing sustainable construction through innovative transparent wood composite structures with enhanced functionalities

Advancements in transparent wood materials hold immense promise for eco-friendly construction, combating resource depletion, and enhancing energy efficiency. Yet, the quest for versatility and global uniformity poses challenges. Enter our breakthrough: a three-layer transparent wood that integrates thermal energy storage. We achieved this by compressing three partially impregnated wood substrates, featuring a silica-stabilized polyethylene glycol (PEG) core flanked by two polymethyl methacrylate (PMMA) layers. In pursuit of optical and mechanical perfection, we employed a multi-layer approach to ensure global isotropy. Morphological analysis unveiled compact, hierarchical structures in the core, PEG encapsulation, and an innovative solution for preventing leaks, culminating in a remarkable latent heat of 15.0 J/g and superior thermal stability. Optical testing reported outstanding properties, with an optical transmittance of 45 % and a haze of 76 % at 800 nm. Our design featuring crossed-lamination not only achieved isotropic light distribution but also improved mechanical consistency and water resistance. Notably, our environmentally-simulated tests showcased remarkable thermal insulation properties, credited to a low thermal conductivity (0.34 W/mK) surpassing traditional glass, as well as phase-change functionality. Our pioneering multilayer transparent wood stands to revolutionize energy-efficient construction and elevate indoor thermal comfort.

Fabrication and performance evaluation of a design for an extended depth-of-focus intraocular lens based on an improved sinusoidal profile.

This study presents the fabrication and evaluation of a sinusoidal extended depth-of-focus (EDoF) intraocular lens (IOL) based on our previously proposed design approach. The power, through-focus MTF, and surface profile were measured using commercial instruments. Through-focus images of a United States Air Force (USAF) 1951 resolution target formed by the fabricated IOL were compared with Symfony and AR40E under monochromatic and polychromatic light using optical bench testing. Simulations assessed visual acuity (VA) of a pseudophakic model eye with the EDoF IOL, including evaluation of tilt and decentration effects. Results indicate that the base power, add power, and the through-focus MTF@50 lp/mm of the fabricated IOL at a 3 mm pupil size align with the design specifications. The extended-depth-of-focus and imaging performance for the far vision of the fabricated IOL under both monochromatic and polychromatic light conditions at a 3.0 mm pupil diameter is comparable to that of Symfony. In addition, the fabricated IOL exhibits a similar extended-depth-of-focus for three discrete wavelengths. The pseudophakic model eye with the designed EDoF IOL demonstrates a VA exceeding 0.1 logMAR within a defocus range of 2.44 D. The VA is tolerant to both IOL tilt and decentration. These findings demonstrate the promising potential of the sinusoidal EDoF IOL design for future applications in cataract surgery.

Stark Broadening, Boltzmann Plot Methods for Calculating Plasma Parameters by Laser-Induced Breakdown Spectroscopy for Gold Target

In this investigation, a spectroscopic optical emission test was used to investigate the characteristics of gold plasmas that were produced in the surrounding environment using an Nd: YAG system at a wavelength of 1064[Formula: see text]nm and had an energy output that varied from 400 to 600[Formula: see text]mJ. The emission spectrum profiles of (Au) were analyzed and recorded using a spectrometer to aid in the extraction of vital plasma features (i.e., [Formula: see text] and [Formula: see text]). Plasma temperature was determined using the Boltzmann plot method, and electron density was determined using the Stark broadening method. The temperature was between (0.91 and 0.94)[Formula: see text]eV, while the electron density ranged between (4.79 and 5.26) [Formula: see text][Formula: see text]cm[Formula: see text]. The rest of the plasma parameters were calculated by the mathematical equations of the method used (Boltzmann Plott).

Making the diamond vortex phase masks for the METIS instrument

Direct observation of exoplanets and proto-planetary disks with the METIS instrument at the Extremely Large Telescope will provide new insights into the processes of planet formation and exoplanet atmospheres. This will be possible thanks to a powerful vector vortex coronagraph that can suppress the starlight to reveal faint signals around it. Here we present the process of making the phase masks at the heart of the coronagraph. These annular groove phase masks consist of deep sub-wavelength gratings in diamond that are etched using inductively coupled oxygen plasma with a strong bias. The METIS instrument requires a wider bandwidth than such components have previously been demonstrated for, leading to a grating design with higher aspect ratio and more vertical walls. To achieve this, the etch mask used for diamond etching was changed from aluminium to silicon and the plasma power was increased. We also improved on our method for reducing the grating depth of finished components to fine-tune them. Together with improved optical testing, this allowed us to produce the best vortex phase masks so far demonstrated for the astronomical N-band.

Optimizing LED array irradiance uniformity with a particle swarm optimization-based scheme: application in a parallel photoreactor

This study proposes a particle swarm optimization (PSO)-based method for enhancing the irradiance uniformity of light emitting diode (LED) arrays in parallel photoreactors. We construct a spatial irradiance model, validating its accuracy with near-field optical test data and optical simulation results. An evaluation function for irradiance uniformity guides the iterative optimization of the LED arrangement, taking into consideration practical constraints such as chip size, heat dissipation, and circuit board wiring. The optimized LED array demonstrated a significant improvement in irradiance uniformity, increasing from 75.27% to 95.61%. This showcases the feasibility and effectiveness of our PSO-based method for practical applications in optimizing LED arrays.

Spatial atomic layer deposition of nitrogen-doped alumina thin films for high-performance perovskite solar cell encapsulation

An atmospheric-pressure spatial atomic layer deposition (AP-SALD) system is used to deposit nitrogen-doped alumina (N-AlOx) thin-film-encapsulation layers. The rapid nature of the AP-SALD process facilitates deposition of 60-nm layers directly on perovskite solar cells at 130 °C with no damage to the temperature-sensitive perovskite and organic materials. Varying the bubbling of a NH4OH precursor varied the nitrogen concentration from 0.08 to 0.68 at%. These small concentrations were found to have a significant impact on the structural properties of the films and their moisture barrier performance. The N-AlOx thin films had slightly higher growth rates than undoped AlOx, less unwanted hydroxyl and carbon content, and were smoother and more compact, which was attributed to a higher flux of reactive species from the volatile NH4OH. Optical calcium tests showed that the N-AlOx films had lower water-vapor-transmission rates (∼10-5 g/m2/day) than undoped AlOx films and the transmission was minimized for 0.28% nitrogen. The increased compactness of the N-AlOx films is expected to minimize nanoscale percolation pathways, whereas higher nitrogen-defect concentrations may facilitate water permeation through these pathways. The stability of n-i-p and p-i-n perovskite solar cells under standard ISOS-D-1 and ISOS-D-3 testing conditions was significantly enhanced by the encapsulation layers. An N-AlOx encapsulation layer with 0.28% nitrogen improved the T80 value of a p-i-n formamidinium methylammonium lead iodide solar cell from 144 hrs to 855 hrs (ISOS-D-1) and 52 hrs to 300 hrs (ISOS-D-3).

Chaos key enhanced physical layer secure transmission method based on the convolutional long short-term memory neural network

In this paper, we propose a method for training a key-enhanced chaotic sequence using the convolutional long short term memory neural network (CLSTM-NN) for secure transmission. This method can cope with the potential security risk posed by the degradation of chaotic dynamics when using chaotic model encryption in traditional secure transmissions. The simulation results show that the proposed method improves the key space by 1036 compared to traditional chaotic models, reaching 10241. The method was applied to orthogonal chirp division multiplexing (OCDM). To demonstrate the feasibility of the proposed scheme, we conducted transmission experiments of encrypted 16 quadrature amplitude modulation (QAM) OCDM signals at a speed of 53.25 Gb/s over a 2 km length of 7-core optical fiber and test different encryption schemes. After key enhancements, the overall number of keys in the system can increase from 18 to 105.The results show that there is no significant difference between the bit error rate (BER) performance of the encryption method proposed in this paper and the traditional encryption method. The maximum performance difference between the different systems does not exceed 1 dBm. This fact proves the feasibility of the proposed scheme and provides new ideas for the next generation of secure transmission.

Development of Low-Weight and High-Strength AA6005A Extrudates Intended for Modern Architecture and Design of Innovative Die for Extrusion Process.

In the realm of modern architecture, the demand for materials that combine strength, durability, and aesthetic flexibility is ever-growing. Addressing this need, this paper presents a study on the innovative use of aluminum extrudates in construction. Focusing on the AA6005 alloy, which is known for its excellent balance of strength, corrosion resistance, and weldability, this research delves into the development of an extrusion process that yields thin-walled, lightweight, yet high-strength structural components. Using FEM simulations, a new extrudate of the AA6005A was developed. It is compatible with standard façade systems, with high-strength properties and a weight reduced by 20% compared to that of conventional extrudates made of the AA6063 alloy. Using CAD engineering and FEM simulations of aluminum extrusion process, an innovative die was designed for the extrusion process, ensuring uniform flow of metal from the bearing and minimizing the elastic deflection of the die. This resulted in an increase in the extrusion velocity of thin-walled extrudate from AA6005A by 24% compared to conventional profiles extruded from AA6063. As part of the research, a trial test was carried out in production conditions and the quality of the extrudates was tested by 3D optical scanning, mechanical and structural properties tests, and microstructure observation.

Investigation of Automotive LiDAR Vision in Rain from Material and Optical Perspectives.

With the emergence of autonomous functions in road vehicles, there has been increased use of Advanced Driver Assistance Systems comprising various sensors to perform automated tasks. Light Detection and Ranging (LiDAR) is one of the most important types of optical sensor, detecting the positions of obstacles by representing them as clusters of points in three-dimensional space. LiDAR performance degrades significantly when a vehicle is driving in the rain as raindrops adhere to the outer surface of the sensor assembly. Performance degradation behaviors include missing points and reduced reflectivity of the points. It was found that the extent of degradation is highly dependent on the interface material properties. This subsequently affects the shapes of the adherent droplets, causing different perturbations to the optical rays. A fundamental investigation is performed on the protective polycarbonate cover of a LiDAR assembly coated with four classes of material-hydrophilic, almost-hydrophobic, hydrophobic, and superhydrophobic. Water droplets are controllably dispensed onto the cover to quantify the signal alteration due to the different droplets of various sizes and shapes. To further understand the effects of droplet motion on LiDAR signals, sliding droplet conditions are simulated using numerical analysis. The results are validated with physical optical tests, using a 905 nm laser source and receiver to mimic the LiDAR detection mechanism. Comprehensive explanations of LiDAR performance degradation in rain are presented from both material and optical perspectives. These can aid component selection and the development of signal-enhancing strategies for the integration of LiDARs into vehicle designs to minimize the impact of rain.

Learning-based lens wavefront aberration recovery

Wavefront aberration describes the deviation of a wavefront in an imaging system from a desired perfect shape, such as a plane or a sphere, which may be caused by a variety of factors, such as imperfections in optical equipment, atmospheric turbulence, and the physical properties of imaging subjects and medium. Measuring the wavefront aberration of an imaging system is a crucial part of modern optics and optical engineering, with a variety of applications such as adaptive optics, optical testing, microscopy, laser system design, and ophthalmology. While there are dedicated wavefront sensors that aim to measure the phase of light, they often exhibit some drawbacks, such as higher cost and limited spatial resolution compared to regular intensity measurement. In this paper, we introduce a lightweight and practical learning-based method, named LWNet, to recover the wavefront aberration for an imaging system from a single intensity measurement. Specifically, LWNet takes a measured point spread function (PSF) as input and recovers the wavefront aberration with a two-stage network. The first stage network estimates an initial wavefront aberration via supervised learning, and the second stage network further optimizes the wavefront aberration via self-supervised learning by enforcing the statistical priors and physical constraints of wavefront aberrations via Zernike decomposition. For supervised learning, we created a synthetic PSF-wavefront aberration dataset via ray tracing of 88 lenses. Experimental results show that even trained with simulated data, LWNet works well for wavefront aberration estimation of real imaging systems and consistently outperforms prior learning-based methods.

Investigation of factors that may affect the foveal avascular zone: An optical coherence tomography angiography study

SIGNIFICANCE An understanding of factors that affect the foveal avascular zone (FAZ) in healthy eyes may aid in the early identification of patients at risk of retinal pathology, thereby allowing better management and preventive measures to be implemented. PURPOSE The size and shape of the FAZ can change due to retinal diseases associated with oxidative stress, including diabetic retinopathy, glaucoma, and macular degeneration. This study aimed to assess the relationship, if any, between factors that may affect the superficial FAZ (i.e., vessel density, vessel perfusion, overweight/obesity) and possible links with macular pigment optical density in young, healthy participants. METHODS One hundred thirty-nine participants aged 18 to 35 years were recruited to this cross-sectional study. The superficial FAZ area, foveal vascularity, and central macular thickness (CMT) were assessed using the Cirrus 5000. Health parameters, body mass index, trunk fat %, and macular pigment were analyzed to determine possible associations with the superficial FAZ. RESULTS Mean FAZ area was 0.23 ± 0.08 mm2. Females had a significantly larger mean FAZ area than males (p=0.002). The FAZ area was positively correlated with body mass index (Pearson's r = 0.189, p=0.026). Significant correlates of the FAZ area in the multivariate model included vessel perfusion (central), CMT, and trunk fat %, collectively explaining 65.1% of the overall variability. CONCLUSIONS Study findings suggest that reduced vessel perfusion, thinner CMT, and higher trunk fat % are plausible predictors of a larger FAZ area in healthy Caucasian adults. Low macular pigment optical density was, however, not associated with increased FAZ size in young healthy eyes. Noninvasive optical coherence tomography angiography testing, in association with these predictors, may aid in the early detection and monitoring of retinal diseases associated with oxidative stress.

Multi-sample joint localization method for intrusion sources around underground pipelines based on cross-correlation convolutional neural networks

Improving the safety monitoring of underground pipelines is crucial for maintaining the structural integrity of critical infrastructure systems. This study introduces an innovative multi-sample joint localization method (MSJLM) based on cross-correlation convolutional neural networks (CC-CNNs) to identify intrusion sources in the vicinity of underground pipelines. Traditional approaches to detecting and locating pipeline intrusions often rely on a solitary sensor monitoring point, making them susceptible to errors and limitations. Presently, widely used distributed optical fiber testing methods tend to yield imprecise localization. In contrast, the MSJLM proposed in this study harnesses data from multiple samples effectively and combines them via correlation analyses to enhance precision and reliability. The CC-CNN framework used to process the collected data is demonstrated to be highly effective in extracting spatial features and recognizing patterns.

Optical and mechanical testing of 3D printed parts made of high-viscosity silicone to identify process parameters and design advice for 3D printing and printer development

AbstractThe additive manufacturing of parts made from close-to-production materials poses a great challenge. One example are highly viscous silicones, as used in injection moulding. For small production quantities, the manufacturing of injection moulds is uneconomical. This paper presents tensile specimens printed with an in-house developed dispensing system, which are analysed for air cavities (micro-CT scans) and mechanical properties. Based on the results, advice for the design and slicing parameters of parts using high-viscosity silicones in AM by means of material extrusion are developed.

Development and characterization of a composite material with geopolymer matrix obtained by incorporation of microparticles from plastic bottles

The composite material with a geopolymer matrix of 7 M molarity, obtained by incorporating microparticles from plastic bottles is developed and characterized in the present paper. To do this, we made cylindrical specimens whose the diameters are the half of their heights and stored them at a temperature of (31±2°C). The compression test using a hydraulic press is carried out, as well as the thermal characterization test using a device respecting the experimental method of the asymmetric hot plane, which was used to determine the thermal conductivity, the volumetric heat capacity, the effusivity and the diffusivity. Then optical characterization tests on hardened samples were carried out, namely chemical analyses of the composition of the kaolin, and particle size characterization of the raw microscopic imaging of the specimens. The results found showed that as the amount of polyethylene terephthalate increases, the compressive strength decreases by 33.65 % for 10%polyethylene terephthalate and 67.77 % for 20 % polyethylene terephthalate. According to the thermal conductivity, it improves with the percentage of polyethylene terephthalate added as: at 10% it is 1.19Wm−1K−1 and at 20%, one has 0.595Wm−1K−1; similarly for effusivity where we obtained 1376.05 JK−1m−2s−1/2 and 560.81 JK−1m−2s−1/2 for 0 and 20% respectively. According to these results, the use of polyethylene terephthalate aggregates as a partial substitute of aluminosilicate raw material for the development of a composite can be a good alternative for recycling plastic bottle waste. The composite obtained could be used for the manufacture of ceiling lights and brick facings, and therefore would significantly reduce the amount of waste plastic produced every day in environment.