Tianfeng Zhou

Monocrystalline silicon is an ideal material for infrared optics microlens arrays, achieving excellent performance, but the processing is extremely difficult and poses a challenge to traditional processing processes. In this paper, a new process flow for processing monocrystalline silicon microlens arrays is proposed, combining femtosecond laser three-dimensional dynamic focusing processing technology with sandblasting and polishing finishing technology. Dynamic focusing technology is used to adjust the focus position in real time to adapt to the complex processing needs of three-dimensional structures, and the influence of different laser processing parameters on the processing size and morphology is studied. The mechanism of processing errors and surface defects is proposed to realize the compensation of three-dimensional processing errors. Through experiments and simulations, a 515 nm green light, 100 KHz repetition frequency, power of about 20 W—maintaining the same scanning speed of 3000 mm/s and isotropic filling scanning interval of 5 μm, with an on delay of 0.23 ms, an off delay of 0.12 ms, a corner delay of 0.13 ms, and a null walk delay of 0.24 ms, and a delamination height of 1 μm—were finally selected for the laser processing. The process parameters are feasible and the processing effect is good, providing a new solution for processing hard and brittle materials.

An optical reflector is an important part of an optical system, and its main function is to reflect light and adjust the light path. In the past decades, it has been widely used in imaging, laser systems, communication and scientific research. Therefore, it is opportune to present a comprehensive review and discuss future development directions. This paper systematically reviews the types of optical reflectors, the differences between diffraction and scattering, and the different uses of reflectors. The factors affecting reflectivity, including reflector quality, coating parameters and material properties, are also introduced. This paper also introduces practical technology to improve reflectivity on the reflector surface. Finally, the development prospects of numerical simulations of reflectivity are introduced, and the methods to eliminate diffraction effects are summarized.

Rapid pressure unloading is essential for the back pressure assembly of injector test systems. In this study, a high-speed unloading valve was developed for the back pressure assembly of an injector test system, and its pressure unloading characteristics were investigated through coupled numerical simulation and experimental testing. An electromagnetic–mechanical–fluid coupled dynamic model was established to describe the interactions among electromagnetic actuation, valve core motion, and hydraulic forces. Three-dimensional CFD simulations were performed to investigate the steady flow and hydraulic-force characteristics, followed by a two-dimensional transient model for analyzing the hydraulic force during valve closure. A coupled Simulink–AMESim model was then established to evaluate the system-level pressure unloading response and compared with experimental measurements under several initial pressure conditions. The CFD results reproduced the variation in flow rate with pressure differential, while sensitivity and uncertainty analyses showed that the quantified factors could not fully account for the discrepancy in absolute flow rate. Three-dimensional CFD revealed both axial and radial hydraulic forces, while 2D–3D comparison supported the use of the two-dimensional model for transient axial-force analysis. The system-level simulation and experimental results exhibited comparable pressure unloading characteristics within the investigated operating range.

Precision glass molding (PGM) is a key process for the mass manufacturing of infrared chalcogenide glass (ChG) microlens arrays (MLAs) for aerospace infrared systems. However, interfacial adhesion between ChG and the mold surface during molding can seriously affect forming quality. Tetrahedral amorphous carbon (ta-C) coatings are promising for reducing mold-glass adhesion owing to their low surface energy and chemical stability. Nevertheless, despite their anti-adhesion potential, the thermal evolution of interfacial interactions between ta-C coatings and ChG under high-temperature molding conditions remains insufficiently understood. In this study, the adhesion-related interfacial behavior of the ChG/ta-C system is investigated by combining molecular dynamics (MD) simulations, high-temperature wetting experiments, and repeated molding experiments. A cross-scale adhesion model is established to correlate atomic-scale interfacial interactions with macroscopic adhesion work and molding performance. The temperature-driven evolution of interfacial atomic configurations, interaction energy, adhesion strength, wettability, and adhesion work is systematically analyzed over 300-400°C. Fifty-cycle molding experiments are further conducted to verify the effect of interfacial adhesion energy on mold service performance and glass forming quality. This work clarifies the temperature-regulated adhesion mechanism of the ChG/ta-C interface and provides theoretical guidance for adhesion suppression, mold lifetime improvement, and process optimization in infrared micro-optical glass molding.

Titanium dioxide nanotubes (TiO₂ NTs) fabricated by electrochemical anodization have attracted attention because their morphology can be regulated by processing parameters. Although the anodic fabrication of TiO₂ NTs has been widely studied, the morphology evolution of nanotubes on Ti6Al4V during secondary anodization after ultrasonic removal of the first nanotube layer still requires further clarification. In this study, anodic nanotubular oxide structures were fabricated on Ti6Al4V substrates by primary anodization and secondary anodization. The effects of anodization voltage, fluoride ion concentration, oxidation time, and secondary anodization on nanotube morphology were investigated. The results show that increasing anodization voltage promotes nanotube formation and increases tube diameter, whereas excessive oxidation time and high fluoride concentration lead to nanograss formation, tube collapse, and surface damage. Compared with primary anodization, secondary anodization produced smaller nanotube diameters and distinct morphology evolution, which may be associated with changes in the initial surface state after ultrasonic removal of the first nanotube layer. Among the investigated conditions, primary anodization at 40 V in 0.5 wt.% NH₄F electrolyte followed by secondary anodization at 50 V produced relatively regular nanotubular regions, although nanograss was also present on the surface. This work provides a process-oriented understanding of TiO₂ nanotube morphology regulation on Ti6Al4V substrates during primary and secondary anodization.

Cylindrical microlens arrays (CMLA) are widely used in optical systems such as one-dimensional focusing, line imaging, and beam shaping, where high requirements are imposed on array uniformity, surface figure accuracy, and surface integrity. In this study, a novel fabrication method for CMLA based on electrochemical machining (ECM) is proposed. Periodic planar nano-groove arrays with well-defined periods and boundary conditions are first fabricated on a heat-resistant stainless-steel based amorphous Nickel–Phosphorus (Ni-P) alloy by ultra-precision scratching. Subsequently, ECM process is conducted to introduce isotropic anodic dissolution and continuous rounding of the groove bottom, resulting in the formation of cylindrical arc profiles. The morphological evolution mechanism is analyzed using a geometric model and numerical simulation, revealing that the curvature of the groove bottom arc is predominantly governed by the material removal amount, while the influence of the initial groove angle is relatively minor. With increasing ECM time, the groove bottom is gradually reconstructed into a smooth cylindrical surface, and the arc radius increases monotonically with an approximately linear relationship. For grooves with a pitch of 800 nm, the bottom arc radius increases from 0.087 μm to approximately 0.577 μm. Elemental analysis indicates that the surface chemical composition of the Ni-P alloy remains essentially unchanged before and after ECM, demonstrating the chemical stability of the proposed process. This method combines the advantages of ultra-precision scratching for structural definition and period control with the low-load and low-damage characteristics of ECM, providing an effective approach for the controllable fabrication of nanoscale CMLA with good interfacial quality.

A digital laser integrated inspection system has been developed to address the requirement for on-site multi-parameter characterization of high-energy laser sources. By means of a front-end beam-splitting architecture, the system enables simultaneous measurement of laser energy and beam quality, while an off-axis dual-reflector optical configuration is employed to evaluate beam pointing stability. At the receiving end, high-precision linear guide rails are incorporated to synchronously determine the beam quality factor (M ² factor), thereby eliminating systematic errors induced by repeated alignment and adjustment procedures. To mitigate interference arising from ghost images generated by transmissive optical components, such as beam splitters and filters, comprehensive models of both primary and secondary ghost-image propagation paths are established. The LightTools software is utilized to quantitatively compute the energy contribution of single-path ghost images, with their relative impact assessed through normalization criteria. Ghost-image formation is effectively suppressed by introducing an angular tilt to the ghost-image generation plane. Simulation results demonstrate that tilting the rear surface of the beam splitter by an appropriate angle completely removes ghost images from the effective field of view. The optimized optical design significantly reduces ghost-image energy and enhances the system signal-to-noise ratio, thereby improving the overall detection accuracy of the integrated inspection system.

Improving the friction-reduction and anti-adhesion performance of nickel-phosphorus (Ni-P) coatings is essential for enhancing mold stability and microstructure replication in precision glass molding (PGM). In this study, nitrogen (N) ion implantation followed by heat treatment (HT) was applied to modify Ni-P coating surfaces and regulate their near-surface structure and interfacial state. Ion implantation simulations and multiscale characterizations were used to investigate the effects of N ion implantation and HT on structural evolution, surface properties, tribological behavior, and PGM performance. The results show that N ion implantation forms a near-surface modified layer with compositional gradients and structural heterogeneity, while HT promotes surface elemental redistribution and Ni-O-related bonding. The modified coating exhibits increased hardness, improved resistance to plastic deformation, and a wettability transition from hydrophilic to weakly hydrophobic. Friction tests indicate that the N-implanted + HT coating shows a lower and more stable coefficient of friction, suggesting reduced interfacial shear resistance. PGM experiments further demonstrate enhanced glass filling of microstructures and suppressed Ni transfer to the glass surface. These improvements are attributed to enhanced load-bearing capacity, reduced real contact area, regulated surface chemistry, and weakened mold-glass adhesion. This work provides insight into surface modification of Ni-P coatings for high-performance PGM molds.