3D Surface Profile Research Articles

Experimental and numerical investigation of sliding wear of heat-treated 316L stainless steel additively manufactured

Additive manufacturing (AM) of metal alloys using a laser as a machine tool is reaching levels of precision comparable to conventional processing methods. Stainless steel specimens fabricated by AM have been extensively evaluated in load-bearing applications, showing an adequate response concerning mechanical strength. However, research on wear behavior remains open to discussion. The present work evaluates the sliding wear response of 316L stainless steel fabricated by laser powder bed fusion in three conditions: (1) as-built, (2) stress-relieved at 550 °C, and (3) heat-treated at 1150 °C. A pin-on-disk tribometer and a nanoindentation tester were employed to assess the tribological response and compare it with the same cold drawing material. The wear track and volume loss were evaluated using a 3D surface profile meter. Furthermore, the finite element method was applied to validate the experimental results and obtain insights into the behavior of the pin and disk couple. The results show that the samples in the as-built condition exhibit higher wear resistance associated with higher hardness. Stress relief slightly alters the wear response, while heat treatment modifies the microstructure, reducing the sliding wear resistance. The wear of the heat-treated samples cannot be attributed to a single wear mechanism, a synergy between several sub-mechanisms, such as abrasion, adhesion, oxidation, and tribochemical reactions.

Chitosan grafted with gallic acid and cerium dioxide hybrid nanocomposites as environmentally friendly corrosion inhibitors for mild steel: An experimental and computational study

Chitosan grafted with gallic acid (CS-GA), along with CS-GA doped with CeO2 nanoparticles (CS-GA-CeO2) were synthesized as novel environmentally friendly mild steel corrosion inhibitors. The formation of these derivatives was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), hydrogen nuclear magnetic resonance spectroscopy (1H NMR), and thermal analysis (TGA). Based on potentiodynamic polarization curves (PDP) measurements, the inhibitors acted primarily as hybrid inhibitors, while following the Langmuir adsorption theory model. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy(XPS) and 3D surface profiles, confirmed that CS-GA-CeO2 adsorbed on the mild steel forming a protective layer thus preventing the invasion of corrosive media. The corrosion protection mechanism of chitosan derivatives was investigated by molecular dynamics simulations. Electrochemical measurements were used to investigate the corrosion inhibition by CS-GA and CS-GA-CeO2 on mild steel in a 3.5 % NaCl solution. At room temperature, the highest inhibition efficiency (93.58 %) was achieved at 200 ppm CS-GA-CeO2. Modified chitosan nanocomposites were confirmed as promising corrosion inhibitors.

Surface roughness prediction model and surface topography analysis of 2.5D-Cf/SiC in two-dimensional ultrasonic assisted grinding based on GA-BP neural network

Because of the anisotropy and non-uniformity, the grinding surface quality of Cf/SiC composites is difficult to be accurately predicted. The quality of the surface directly determines the assembly accuracy. To better predict the surface quality of 2.5D-Cf/SiC composites, the BP neural network was optimized by genetic algorithm (GA), and the surface roughness prediction model of fiber orientation, ultrasonic amplitude, and machining parameters was established. The empirical formula prediction model of surface roughness was established by the method of multiple linear regression analysis. The results show that the prediction accuracy of GA optimized BP neural network is the best, followed by the empirical formula, and the prediction effect of the BP neural network is the worst. The average absolute percentage error of these three models is 10.045%, 16.912% and 26.6245% respectively. The kinematic models of conventional and two-dimensional ultrasonic-assisted grinding of single particles were established respectively. Based on the kinematic model, the reasons for the reduction of surface roughness by 2D ultrasonic-assisted grinding are explained. According to the orthogonal test results, the surface roughness decreases the most when vs is 0.66m/s, vw is 100mm/min, ap is 150μm along the fiber orientation of 0°, and the maximum percentage of reduction is 53.18%. Increasing the linear speed, reducing the feed speed, reducing the grinding depth, and applying ultrasound can reduce the extrusion pressure along the axis of 0° fiber, and then reduce the length and depth of cracks and thus reduce the surface defects. The axial shear force of the 90° oriented abrasive particles on the fiber is reduced, thus reducing the surface damage caused by torsional deformation. Reduce 3D surface profile and improve surface quality. The maximum percentage reduction of each parameter index is as follows: root mean square height decreased by 28.8%, skew decreased by 88.61%, kurtosis decreased by 48.97%, maximum crest height decreased by 48.55%, maximum sag height decreased by 40.09%, maximum height decreased by 43.93%, and arithmetic mean height decreased by 26.06%.

Wear behaviour analysis of thermo-mechanically processed AA7075 and AA7075/SiC/Graphite composite

The current work focuses on investigating the tribological performance of AA7075 alloy and AA7075 hybrid composite with SiC and graphite reinforcements of 2 and 0.5 wt percentages, respectively. The alloy and hybrid composite are fabricated through stir casting and thermo-mechanically processed through hot rolling routes. Dry sliding wear characterization has been carried out using a pin-on-disc wear testing setup for alloy and composite under various processing conditions using experiments designed according to Taguchi's L9 orthogonal array. The technique for order preference by similarity to ideal solution (TOPSIS) method has been adopted to achieve a single multi-response index (MRI) considering the minimization of multiple objective functions for specific wear rate (SWR) and coefficient of friction (COF). The analysis of variance (ANOVA) results of the MRI indicated that sample processing condition and load were the most significant parameters. The wear mechanism at different experimental conditions was studied using Scanning electron microscope (SEM) micrographs, energy dispersive spectroscopy analysis and 3D surface profile of wear track. The AA7075 composites are found to be comparatively good in all experimental conditions compared to the base alloy due to load-bearing SiC particles and solid lubricant graphite as reinforcing elements. The mechanically mixed layer (MML) formation in hybrid composites helped achieve good tribological properties. The AA7075 alloy and hybrid composites cross rolled at 350 °C yielded better results than other samples. The wear mechanism was abrasive and adhesive at low temperature and low load conditions in both alloy and hybrid composites. Whereas, at higher temperatures and high loads oxidative wear mechanism with delamination was prevalent. The transition of SWR from mild to severe value occurs at 250 °C in all experimental cases. The specific wear rate was improved by 85.64 % between worst and best conditions, i.e., annealed alloy and cross rolled composite.

Bond strength of epoxy-based composites at the interface with surface deposited metal layer: A comparative study with different dimensional fillers

With the complexity of the working environment, pure epoxy resin can no longer meet the requirements, and the weak interfacial bonding between metal layer and epoxy-based composites limits its development. In this work, we propose a novel molecular grafting modification technique by using the active functional groups of polymers, which can apply to epoxy-based composites with various fillers to improve the adhesive strength of the interface between the metal film and matrix. 3D surface profile and surface wettability were used to characterize the effect of fillers on the surface of epoxy composites. Scanning electron microscope (SEM) and Raman spectroscopy were utilized to judge the interface failure modes of the composites. Peeling test and surface-enhanced Raman scattering (SERS) were conducted to examine how fillers affected adhesion. The results showed that silane grafting substantially improved the bonding between the epoxy-based composite matrix and the metal layer without the need for alkaline washing and palladium (Pd) activation steps on the substrate. The average adhesive strength can reach a maximum of 17.76 N/cm. The study also revealed the effect of filler size on the interfacial adhesive strength. The interfacial adhesive strength was increased by two dimensional lamellar materials, decreased by one-dimensional tubular materials, and remained unaffected by zero-dimensional spherical materials. This study may have positive implications for improving interfacial bonding between metal and polymer composite surfaces.

Analysis of the Mechanical and Physical Behaviors of 3D-Printed PEEK Structures under Different Parameters

In this study, the mechanical and physical properties of polyetheretherketone (PEEK) material produced through three-dimensional (3D) printing under different production parameters were investigated. For this purpose, the results obtained by applying heat treatment to the produced samples were examined. Comparisons based on mechanical properties were supported by 3D surface profiles and XRD analyses. According to the obtained results, low nozzle diameter and high printing temperature led to an increase of up to 8% in the elastic modulus and up to 33% in tensile strength of the samples. The heat treatment applied in the study increased tensile strength by up to 8% and elastic modulus by up to 9% in samples produced with a low-diameter nozzle. In conclusion, this study aims to provide a dataset for 3D PEEK designs, intending to enhance the performance of PEEK materials that can be used in medical and industrial applications.

Corrosion protection characteristics of doped magnetite layers on carbon steel surfaces in aqueous CO2 environments

Magnetite (Fe3O4) corrosion product surface layers can limit uniform corrosion rates of carbon steel in aqueous carbon dioxide (CO2)-saturated environments. However, as Fe3O4 is a semiconductor, localised corrosion can proceed due to galvanic interaction between the Fe3O4 layers and bare steel. In this study, metal dopants were integrated into Fe3O4 layers to mitigate the effects of localised corrosion, whilst maintaining its protective barrier properties. Model Fe3O4 and metal-doped Fe3O4 layers were electrodeposited on carbon steel and immersed in a pH 5, 1 wt% sodium chloride (NaCl), CO2-saturated, 50 °C solution. Under the conditions studied, the incorporation of magnesium into the Fe3O4 layer resulted in reduced localised corrosion when the 3D surface profiles of the underlying carbon steel were measured using white light interferometry.

A High-Resolution Measurement Method for Inner and Outer 3D Surface Profiles of Laser Fusion Targets Using a Laser Differential Confocal–Atomic Force Probe Technique

The high-resolution and nondestructive co-reference measurement of the inner and outer three-dimensional (3D) surface profiles of laser fusion targets is difficult to achieve. In this study, we propose a laser differential confocal (LDC)–atomic force probe (AFP) method to measure the inner and outer 3D surface profiles of laser fusion targets at a high resolution. This method utilizes the LDC method to detect the deflection of the AFP and exploits the high spatial resolution of the AFP to enhance the spatial resolution of the outer profile measurement. Nondestructive and co-reference measurements of the inner profile of a target were achieved using the tomographic characteristics of the LDC method. Furthermore, by combining multiple repositionings of the target using a horizontal slewing shaft, the inner and outer 3D surface profiles of the target were obtained, along with a power spectrum assessment of the entire surface. The experimental results revealed that the respective axial and lateral resolutions of the outer profile measurement were 0.5 and 1.3 nm, while the respective axial and lateral resolutions of the inner profile measurement were 2.0 nm and approximately 400.0 nm. The repeatabilities of the root-mean-square deviation measurements for the outer and inner profiles of the target were 2.6 and 2.4 nm, respectively. We believe our study provides a promising method for the high-resolution and nondestructive co-reference measurement of the inner and outer 3D profiles of laser fusion targets.

Global flattening realization and kinematic analysis of UV-assisted low-speed 3D dynamic friction-polished diamonds

Diamond has attracted extensive attention from many scholars because of its unique properties. However, there are still bottlenecks in how to achieve high efficiency polishing and global flattening of diamond which restrict its application. The aim of this study is to obtain a globally homogeneous flattened diamond surface in macro dimension by introducing a compound motion of the polished workpiece. It is shown that ultra-smooth diamond surface machining with global flattening can be realized by UV-assisted low-speed dynamic friction polishing technique, and the typical roughness is 0.175 nm as measured by 3D optical surface profiler. These experimental results demonstrate that the catalytic phase transition process of UV light is the underlying mechanism to realize the diamond surface polishing under low rotational speed conditions. Additionally, the composite motion of the diamond sample with the metal disk brings large enhancement to the effect of polishing global flattening on the sample surface. The theoretical and experimental studies in this paper provide novel ideas for achieving efficient and polished global flattening of diamond.

Modelling and Optimization of Machined Surface Topography in Ball-End Milling Process.

In order to optimize machined surface topography, this paper presents a novel algorithm for simulating the surface topography and predicting the surface roughness of a ball-end milling process. First, a discrete workpiece model was developed using the Z-map method, and the swept surface of a cutter edge was represented using triangular approximation. The workpiece surface was updated (i.e., material removal process) using the intersection between the vertical reference line and the triangular facet under a cutting judgement. Second, the proposed algorithm was verified by comparing the simulated 3D surface topography as well as 2D surface profile and average roughness (Sa) with experimental measurements. Then, numerical simulation examples planed by the Box-Behnken design methods were carried out to investigate the Sa in the ball-end milling operation. The correlations of Sa and cutting parameters were represented by a response surface reduced quadratic model based on the ANOVA results. Finally, the feed per tooth, radial depth of cut, and tilt and lead angles were optimized for improving the machining efficiency under the Sa constraints. This study presents an effective method for simulating surface topography and predicting the Sa to optimize the cutting parameters during ball-end milling process.

A 3D Computational Model of Nanosecond Pulsed Laser Texturing of Metals for Designing Engineered Surfaces

Abstract Laser surface texturing uses a pulsed laser that is scanned on the surface, wherein each pulse creates a micro-crater through material ablation. A variety of textures can be generated depending on the laser parameters and the overlap of the laser spots. This work presents a computational model that can predict the topography of a textured surface produced using a nanosecond pulsed laser. The model involves a multi-physics approach that considers laser ablation with plasma effects and the melt pool’s fluid dynamics to obtain the crater profile for a single pulse. The 3D surface profile created from the multi-physics model is mathematically superimposed to mimic the spatial overlapping of multiple pulses. The model predicts surface topography when a laser is scanned along a linear track with successive overlapping tracks. The experiments have confirmed that the proposed model has an accuracy greater than 90% in predicting surface roughness (Sa), as well as volume parameters such as core void volume (Vvc) and valley void volume (Vvv). It was observed that the variation of these surface characteristics is highly non-linear with the process parameters. Furthermore, the model is used to design engineered surfaces to modify friction coefficient, adhesion, and leakage probability. It is demonstrated that the surface parameters for functional requirements can be modified significantly just by varying the overlap of the laser spots in different directions. The proposed model can be used to create textured surfaces for various applications through an appropriate choice of laser parameters and scanning parameters.

Design and Effect of Resonant Ultrasonic Vibration-Assisted Laser Cladding (R-UVALC) on AlCrFeMnNi High-Entropy Alloy.

The design of the resonant ultrasonic vibration-assisted laser cladding (R-UVALC) setup involved employing finite element analysis (FEA) to simulate the ultrasonic transducer, horn, and workpiece in a resonance state. The impact of R-UVALC on AlCrFeMnNi high-entropy alloys was assessed using various ultrasonic vibration amplitudes of 0, 5, 10, and 15 µm, with a constant frequency of 20 kHz. Ultrasonic vibrations reduced pores and cracks and increased the clad breadth, melt pool wetting angle, and laser-clad layer consistency. The columnar elongated grains in proximity to the substrate surface underwent a size reduction and transformed into grains with a more equiaxed shape with the utilization of ultrasonic vibrations at an amplitude of 5 µm. Laser cladding performed without ultrasonic vibrations yields two phases: face-centered cubic (FCC) and body-centered cubic (BCC). However, when the coating is exposed to ultrasonic vibrations with an amplitude of 5 µm, it forms a solitary body-centered cubic (BCC) phase. The microhardness tripled compared to the substrate, and the most significant microhardness value was achieved at 5 µm of ultrasonic vibration. The friction coefficient was assessed at an ambient temperature, revealing that an ultrasonic amplitude yields the lowest friction coefficient, demonstrating the excellent wear resistance properties of the coating. The analysis of the 3D surface profile of the wear indicates that the use of ultrasonic aid with a 5 µm amplitude leads to reduced depth of scars, and the primary wear mechanism observed is abrasive and oxidative wear with fewer grooves and debris. In addition, XPS analysis revealed the presence of metal components in an oxidized condition, suggesting that the wear process is oxidative in nature. Integrating the R-UVALC setup into a resonance state can significantly enhance the efficiency of the laser cladding process in the laser cladding field.

NMSCANet: stereo matching network for speckle variations in single-shot speckle projection profilometry.

In single-shot speckle projection profilometry (SSPP), the projected speckle inevitably undergoes changes in shape and size due to variations such as viewing angles, complex surface modulations of the test object and different projection ratios. These variations introduce randomness and unpredictability to the speckle features, resulting in erroneous or missing feature extraction and subsequently degrading 3D reconstruction accuracy across the tested surface. This work strives to explore the relationship between speckle size variations and feature extraction, and address the issue solely from the perspective of network design by leveraging specific variations in speckle size without expanding the training set. Based on the analysis of the relationship between speckle size variations and feature extraction, we introduce the NMSCANet, enabling the extraction of multi-scale speckle features. Multi-scale spatial attention is employed to enhance the perception of complex and varying speckle features in space, allowing comprehensive feature extraction across different scales. Channel attention is also employed to selectively highlight the most important and representative feature channels in each image, which is able to enhance the detection capability of high-frequency 3D surface profiles. Especially, a real binocular 3D measurement system and its digital twin with the same calibration parameters are established. Experimental results imply that NMSCANet can also exhibit more than 8 times the point cloud reconstruction stability (Std) on the testing set, and the smallest change range in terms of Mean~dis (0.0614 mm - 0.4066 mm) and Std (0.0768 mm - 0.7367 mm) when measuring a standard sphere and plane compared to other methods, faced with the speckle size changes, meanwhile NMSCANet boosts the disparity matching accuracy (EPE) by over 35% while reducing the matching error (N-PER) by over 62%. Ablation studies and validity experiments collectively substantiate that our proposed modules and constructed network have made significant advancements in enhancing network accuracy and robustness against speckle variations.

Fatigue life prediction of electron beam melted micro-sized parts based on regenerated surfaces using machine learning approach

Fatigue life prediction of electron beam melted micro-sized parts based on regenerated surfaces using machine learning approach

Effect of Superplasticizer in Cement Type on Morphological Characteristics of Masonry Mortar

Cement plays a crucial role in mortar composition, and its particles exhibit a strong tendency to flocculate when mixed with water. This flocculation necessitates the addition of substantial water to improve the workability of mortar or concrete. However, this extra water does not contribute to the hydration reaction, potentially weakening the mechanical properties of the mortar. The introduction of superplasticizers has addressed this issue by reducing the water demand. Nevertheless, a common practice in construction is to use a standard dosage of superplasticizers for the same type of cement, even when sourced from different cement factories, which may affect material performance. This study investigated the influence of varying superplasticizer dosages on Portland pozzolana cement from different Ethiopian cement factories, examining the morphological characteristics of masonry mortar. Specifically, it evaluated the impact on cracks, porosity, and surface structure across different curing ages, as well as assessed the mortar’s physical and mechanical properties. Mortar samples prepared using cement from three factories, labeled A, B, and C, with constant cement‐to‐sand ratios of 1:3 and water‐to‐cement ratios of 0.5. Superplasticizer added in varying amounts 0%, 0.6%, 0.8%, and 1%. The morphological analysis conducted using a 3D optical surface profiler microscope at 1, 7, 21, and 28 days. Besides these standard physical and mechanical tests also performed on all samples. The results demonstrated that addition of superplasticizers significantly influenced the surface morphology of mortar samples. Mortars A and B exhibited denser structures with superplasticizer dosages 0.8% and 1%, respectively, whereas mortar C displayed a denser structure in its control state (without superplasticizer). The flexural and compressive strength tests also revealed notable differences. Sample A2 (0.8%) from group A, sample B3 (1%) from group B, and sample C0 (0%) from group C achieved the highest strength within their respective groups at 28 days. The findings suggest that it is essential to evaluate the specific properties of cement before applying a standardized superplasticizer dosage, as variations in cement production can significantly influence the performance of the mortar.

New insight into the structural, elastic, dynamics and thermodynamic properties of Fe3P under high pressures

Many efforts have been devoted to developing the linkage between atomic characteristics and the mechanical properties. Equilibrium lattice parameters, elastic constants, dynamics and thermodynamic properties of Fe3P are systematically explored by density functional theory (DFT) calculations with a generalized gradient approximation (GGA) from Perdew-Wang's 1991 (GGA-PW91), Perdew-Burke- Erzenhof (GGA-PBE), local density approximation (LDA), GGA-PW91+U, GGA-PBE + U and (LDA) + U method (U is the Hubbard correction), respectively. It concluded that the lattice parameters and bulk modulus B from GGA-PBE + U results tend to be more compatible with experimental results than others. The elastic moduli of Fe3P is reported based on the Voigt-Reuss-Hill model. Meanwhile, the anisotropy index and the three dimensional (3D) surface profile of Young's modulus determine the anisotropy. The obtained results indicate that Fe3P exhibits strong elastic anisotropy under high pressure. In addition, the dynamical and mechanical stabilities of Fe3P are confirmed by calculating the phonon and elastic constants up to 40 GPa. Finally, we studied the thermodynamic properties of Fe3P under pressures based on quasi-harmonic approximation.

Influence of forming directions on surface quality of 316L produced by selective laser melting additive manufacturing

Different forming directions have significant impact on surface quality in additive manufacturing. This study is aimed at exploring how different forming directions influence surface quality in additive manufacturing (AM). First, experiments were designed to prepare 316L stainless steel by selective laser melting additive manufacturing (SLAAM) in different forming directions. Moreover, the surfaces of samples manufactured by AM were tested using a three-dimensional (3D) surface profiler and a scanning electron microscope. Furthermore, the surface quality was characterized using four parameters, maximum height, S z ; maximum valley depth, S v; standard deviation of height, S q ; and arithmetic average height, S a. The following results were obtained: (a) different forming directions corresponded closely to upper surface roughness S a values, the values of S a being 7.16 and 8.20 μm, respectively. S a was the smallest among the four parameters; it showed good stability and statistical significance. (b) In the same forming direction, the upper surface roughness values followed the order S z > S v > S q > S a. S z was the largest, exceeding 800 μm; the average value S a was the smallest, reaching 7.36 μm. The values of S q , S z and S v vary when the forming direction changed. Specifically, all of them increased when the forming direction changed from a vertical direction to planar and lateral directions in turn. (c) In different forming directions, the values of S z , S v, S q and S a varied on different surfaces but their variations were basically similar. Meanwhile, the S z , S v, S q and S a values of the free surfaces were at least ten times greater than those of the printed surface. In the SLAAM process, it was necessary to select a forming direction reasonably for parts with different dimensional parameters on each side.

Effect of Si contents on microstructure and mechanical characteristics of TiAlSiN thin film deposited by HiPIMS using different Ti[sbnd]Si target compositions

High Power Impulse Magnetron Sputtering (HiPIMS) PVD deposition technology offers smoother coating enhanced mechanical properties and improved substrate-coating adhesion and has become a superior alternative to direct current magnetron sputtering (DCMS). The technology utilizes high peak power with a small pulse duration, leading to a much denser plasma in the order of 1018 m−3. This results in dense, defect-free, and high-quality smoother coatings. In this study, TiAlSiN coatings were deposited on WC-10Co (wt%) cermet using HiPIMS technology with two different TiSi contents. A pair of TiSi targets, either of compositions Ti77Si23 or of Ti66Si34, were used during the depositions along with another pair of Ti40Al60, in successive cathode-stages. The impact of Ti and Si atomic percentages on the microstructure and mechanical properties of the coatings was investigated using various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), 3D-surface profiling, nano-indentation, Rockwell indentation-adhesion, and scratch test. The coating's thickness and deposition rate were estimated from the cross-section morphology. The results suggested that the TiAlN phase likely existed in an amorphous phase of Si3N4 in TiAlSiN coatings. As the Ti atomic percentage in the layer increased, the hardness improved, reaching up to 42 GPa (max). Additionally, the coating surface roughness decreased from 14.3 nm to 10.9 nm, and the grain size decreased from 10 nm to 9 nm. The adhesion strength observed under the Rockwell-indentation test was rated as HF1 in both cases. Furthermore, the indentation test revealed similar crack patterns, but an increase in Ti content significantly improved the coating-substrate adhesion, as confirmed by the Scratch test. The scratch test demonstrated a maximum load of 173 N during the complete delamination (Lc3) of TiAlSiN from the carbide substrate.

Femtosecond laser micro-machining of three-dimensional surface profiles on flat single crystal sapphire

In this study, a regression model is proposed using the machine learning (ML) method for femtosecond laser micro-machining of three-dimensional (3D) surface profiles on flat single-crystal sapphire. Based on the ML regression model, a quantitative relationship is established between the femtosecond laser processing parameters and the processed 3D functional curved surface topography. The combination of laser processing parameters (i.e. laser fluence F0, hatch dh, and scanning speed v) is also optimized according to the predicted parameters (i.e. surface quality Ra, ablation depth Z, and material removal rate MRR). Finally, the optimized combination of laser processing parameters was employed to process 3D surface profiles on flat single-crystal sapphire sheets. The maximum predicted profile error of the 3D structures was approximately 12.6% without any prior optimization experiments. Both the numerical simulation and experimental results demonstrate the feasibility of the proposed ML regression model in optimizing laser processing parameter combinations to achieve the desired 3D surface geometries on single-crystal sapphire by femtosecond laser micro-machining without trial-and-error.

Polarized structured illumination microscopy using polarization gratings for optical sectioning.

In this investigation, we describe polarized structured illumination microscopy based on polarization gratings to generate a stable polarized illumination pattern in an extensive area. The visibility of the illumination pattern is immediately calculated by using a polarizing pixelated camera, and the 3D surface profile of the specimen can be successfully reconstructed. Moreover, a polarization grating pair was used to reasonably eliminate the unexpected pattern caused by the polarization grating itself. To experimentally characterize the system performance, a step height standard specimen was measured. Moreover, the axial response for the visibility of the illumination pattern was discussed with the consideration of the spectral bandwidth of the source and the spatial coherence of incident light.