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Published
, Published online: 29 April 2026
, doi: 10.37188/lam.2026.053
Characterizing the optical homogeneity of side-polished cylindrical transparent materials remains challenging. To address this challenge, a four-step absolute measurement method based on a Fizeau interferometer is proposed for cylindrical transparent materials. The refractive index distribution is derived from wavefront data obtained through four sequential measurements: empty-cavity interference, transmission interference, front-surface interference, and back-surface interference. A homogeneity error of 1 × 10−5 was introduced in MATLAB simulations, yielding a result of 9.9999 × 10−6 with a residual error of 8.0319 × 10−11, confirming the method’s validity. Two repeated measurements performed at different times yielded homogeneity values of hom1 = 9.5802 × 10−6 and hom2 = 9.3331 × 10−6 (2.7% deviation), demonstrating good robustness. The uncertainties of the two measurements were 1.0997 × 10−6 and 0.8767 × 10−6, respectively, and the expanded uncertainties were 2.1994 × 10−6 and 1.7534 × 10−6, respectively. This method effectively isolates surface errors from material homogeneity, providing a practical approach for the accurate characterization of cylindrical optical components.
Published
, Published online: 22 April 2026
, doi: 10.37188/lam.2026.045
Overcoming the trade-off between a wide field of view (FOV) and compactness remains a central challenge for integrating near-infrared (NIR) imaging into smartphones and AR glasses. Existing refractive NIR optics cannot simultaneously support ultrawide angles above 100° and ultrathin total track lengths (TTL) below 5 mm, fundamentally limiting their integration into portable devices. Herein, we present a wafer-level-manufactured meta-aspheric lens (MAL) that simultaneously achieves a 101.5° FOV, 3.39 mm TTL, and F/1.64 aperture within a compact volume of 0.02 cm3. Unlike previous hybrid systems that rely on separate refractive and diffractive components, the proposed MAL introduces a fully integrated architecture that provides a compact form factor. This integration also simplifies fabrication by enabling high-throughput production via micrometre-level precision alignment and bonding on a single wafer, which requires only one dicing step and no additional mechanical fixtures. Furthermore, the design process incorporates manufacturability and enables metalens dispersion modelling, ensuring that the experimental performance matches simulation results. We validated the MAL method using both direct and computational imaging experiments. Despite its small form factor, our scalable MAL demonstrated strong NIR imaging performance in eye tracking, blood vessel imaging, and computational pixel super-resolution tasks. This scalable MAL technology establishes a new benchmark for high-performance miniaturised NIR imaging, and opens the door for next-generation smartphones and AR optical systems.
Published
, Published online: 12 May 2026
, doi: 10.37188/lam.2026.049
As semiconductor manufacturing advances towards finer feature sizes, mask optimization (MO) has become increasingly critical in optical lithography to ensure pattern fidelity. In extreme ultraviolet (EUV) lithography, full-chip MO encounters significant challenges in terms of computational accuracy and efficiency, which are exacerbated when employing curvilinear patterns. Herein, we propose a full-chip curvilinear MO framework for EUV lithography that integrates deep-learning-enabled forward modelling with gradient-based inverse optimization. We represent the forward model using a tuneable U-net trained on data generated by an accurate and efficient modified Born series method. This model achieves a significantly lower complexity by describing the 3D mask effect through amplitude and phase perturbations. For inverse optimization, gradients are calculated via the adjoint method using slices of the 3D mask field as input—a significantly more efficient approach than utilising the entire 3D field. Evaluated under typical scenarios, the proposed framework demonstrates a four-order-of-magnitude speedup compared with MO based on the finite-difference time-domain method without compromising accuracy. Leveraging this framework, the MO for a 1 mm2 wafer area with 19.41 nm critical dimensions can be completed in 31.7 h using 1,000 GPUs, highlighting its potential for full-chip EUV curvilinear mask optimization.
Published
, Published online: 22 August 2026
, doi: 10.37188/lam.2026.099
Refractory high-entropy alloys (RHEAs) have attracted considerable interest owing to their excellent mechanical strength and thermal stability. However, their inherent brittleness and low thermal conductivity pose significant challenges for high-precision micromachining at room temperature. Conventional nanosecond lasers (CNL) and wire-electrode cutting inevitably cause severe thermal damage and reduce machining quality. In this study, water-jet guided laser (WJGL) technology was utilised for the precision machining of a carbide-reinforced NbMoTaW RHEA. Benefiting from synergistic ablation, cooling, and debris removal effects, WJGLs enable a much cleaner machining interface with minimal spattering compared with CNL and femtosecond lasers. Notably, WJGLs reduced the heat-affected zone to 298 nm, which was ~99.1% lower than that of the CNL. A minimum drilling taper of 0.014° was achieved, indicating ultrahigh micromachining precision. The material removal mechanism and microstructural evolution were elucidated. This study provides a reliable approach for the precision manufacturing of hard-to-process RHEAs.
Published
, Published online: 22 August 2026
, doi: 10.37188/lam.2026.084
Ultrafast laser processing has emerged as a powerful tool for high-precision 3D microfabrication due to its ability to induce localised structural modifications in transparent materials by non-linear multi-photon absorption. In this study, we demonstrated high-precision parallel laser processing by individual axial control of two laser focal spots using a single focusing lens. The proposed method was based on the divergence focus control (DFC) concept, where the focal spot position along the beam axis in the material volume could be controlled by tailoring the laser beam divergence. Numerical simulations confirmed the influence of the axial shift in response to variations in the laser beam divergence. In addition, ray-tracing propagation combined with vector diffraction theory was used to evaluate the influence of spherical aberrations and partial aperture filling on the focal spot morphology and spatial intensity distribution. Experiments were carried out and the results showed that axial focal shifts exceeding 900 µm were achieved by only using a standard microscope objective with a numerical aperture of 0.4. Furthermore, individual control of the two focal points was attained, allowing parallel laser writing with high precision inside transparent materials. For experimental validation, a pair of parallel patterns with different axial distances was fabricated on photosensitive glass, which exhibited high controllability. This method provides a scalable and compact solution for parallel 3D microfabrication and offers advantages such as reduced costs, ease of operation, and straightforward integration into the existing experimental set-up compared with other conventional focusing strategies.
Published
, Published online: 21 August 2026
, doi: 10.37188/lam.2026.082
Wire-grid polarizers, which consist of a one-dimensional periodic metasurface, are convenient polarising elements used in many optical applications. However, these metasurfaces are still incapable of switching the polarisation state of transmitted light without mechanical rotation. This article presents the design of a switchable wire-grid polariser based on a one-dimensional metasurface composed of the phase-change material Ge-Sb-Te (GST). Using the Fourier modal method and genetic-algorithm-based optimisation, we designed a metasurface that transmits two orthogonal linear polarisations of light in different phase states. We demonstrate that the designed metasurface is stable with respect to variations in wavelength and angle of incidence, as well as variations in the geometrical parameters of the metasurface. This concept was verified by measuring the transmission characteristics of a GST metasurface fabricated using magnetron sputtering on a glass substrate. The experimental extinction ratio of the fabricated samples in both polarisation states ranged between 10 and 14~dB, depending on the specific sample. Because the phase transition in GST films can occur on a sub-microsecond timescale, the developed switchable wire-grid polariser offers significant potential for creating a fast, compact polarisation modulator for telecommunication wavelengths.
Published
, Published online: 19 August 2026
, doi: 10.37188/lam.2026.103
Micro-light-emitting diode (micro-LED) displays are prime candidates for near-eye displays, where increasing the panel diagonal at a fixed pixel density is essential to expand the field of view. However, scaling the active area while maintaining luminance homogeneity presents a challenge, primarily due to the pixel-to-pixel current variation in CMOS driven and process-induced non-uniformities in LED arrays. Here we address this trade-off by combining per-pixel current regulation with an optimized fabrication flow in a heterogeneous integration strategy that couples green GaN-based micro-LED with a custom Si CMOS backplane via wafer bonding. The resulting 0.99-inch prototype (1,472 × 1,104 pixels, 14 µm pitch, 1,814 PPI) exhibits >90% brightness uniformity across the active area, peak luminance exceeding 20,000 cd·m−2, a wide viewing angle (>120°), and excellent electrical consistency. These results demonstrate that our heterogeneous integration approach can chart a path toward larger, uniform, and power-efficient micro-displays.
Published
, Published online: 18 August 2026
, doi: 10.37188/lam.2026.091
Micrometre-sized quantum-dot light-emitting diodes (Micro-QLEDs) have been successfully demonstrated as a promising technology for augmented reality (AR) microdisplay applications. To facilitate industrial applications, we developed a two-inch wafer-scale fabrication process for Micro-QLEDs, including the fabrication of a photolithography template, spin-coating fabrication of a QLED, and dicing of a 2-inch wafer into 0.46-inch Micro-QLED panels. Considering the challenge posed by the limited droplet spreading of quantum dots during spin-coating fabrication, we introduced a binary solvent of hexane and octane to achieve a wafer-scale spreading area. In situ high-speed microscopic observations revealed the critical role of Marangoni flow in determining the dynamics of a three-phase contact line. We further designed a 2-inch wafer-scale fabrication process for Micro-QLEDs with an active emitting area of 1,600 mm2, which provides fifteen microdisplay panels with a 0.46-inch Micro-QLED per wafer, achieving a resolution of 2,510 pixels per inch (a pixel size range of 4–50 μm). In addition, the red, green, and blue Micro-QLED wafers had high external quantum efficiencies of 22.8%, 20.8%, and 1.4%, respectively. The 2-inch wafer-scale fabrication process for Micro-QLEDs provides a feasible method for the industrialisation of Micro-QLED technology.
Published
, Published online: 17 August 2026
, doi: 10.37188/lam.2026.089
High-resolution pixelated patterning of quantum dot colour-conversion (QDCC) layers is of significant importance for advancing display technologies. However, a significant challenge lies in the fabrication of high-resolution pixel templates with submicron precision and geometric uniformity. In this study, a high-precision and scalable femtosecond (fs) laser drilling method is used to fabricate microhole arrays in SU-8 polymers. The results show that, compared with Gaussian beams, Bessel-beam irradiation enables the formation of taper-free microholes with smooth sidewalls and diameters as small as 100 nm, while preventing damage to the underlying glass substrate. The fabricated microholes are used as a micropore mould to fabricate monochrome and dual-colour QDCC layers by precisely filling them with CdSe QDs. These layers exhibit narrow-band fluorescence with full widths at half maximum (FWHMs) of 21 nm (green) and 20 nm (red), high colour purity, and a wide colour gamut reaching 111% of the National Television System Committee (NTSC) standard. Pixel-level photoluminescence (PL) mapping confirms homogeneous emission, with 93% of both red- and green-pixel intensities falling within narrow ranges and luminous uniformities of 90% and 97%, respectively. This maskless and solvent-free process offers a promising platform for high-resolution QDCC layers in augmented reality/virtual reality (AR/VR) systems and next-generation micro-light-emitting diode (micro-LED) displays.
Published
, Published online: 13 August 2026
, doi: 10.37188/lam.2026.093
Precisely separating full-band surface errors is a cornerstone of high-performance optical manufacturing and testing. However, traditional methods rely on subjective frequency band definitions and manual filtering, which leads to inconsistent evaluation standards and introduces analysis errors. Meanwhile, existing data-driven methods mechanically fit noisy manual labels, lacking physical consistency. To address this issue, this paper presents a scale-adaptive physics-aware deep learning framework powered by a dual-domain physics-aware network, which extracts error features by imposing physical constraints in the frequency domain: a specifically shaped spectral domain selective attention mechanism is designed for a low-frequency error with a deterministic spectral envelope; an adaptive learnable spectral gating is designed for mid-frequency error with randomness and anisotropy. Experiments indicate that this network outperforms conventional models under adopted evaluation metrics and exhibits physics-constrained extraction behaviour. This helps mitigate measurement noise and subjective variability introduced by manual filtering, yielding results with improved spectral and physical consistency. Furthermore, it eliminates the reliance on high-performance computing hardware, thereby enabling millisecond-level real-time inference on a standard computer, which greatly facilitates practical engineering deployment. Based on these findings, this study proposes a generalised frequency band division method based on normalised spatial frequency, providing a normalised-frequency-based method for a more consistent cross-scale and cross-instrument frequency band error division.
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