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Published
, Published online: 16 September 2026
, doi: 10.37188/lam.2026.128
Additive manufacturing using 2-Photon Polymerization (2PP, aka direct laser writing DLW) enables the fabrication of almost arbitrary complex 3D structures from the meso to the sub-micron scale. However, deviations between the anticipated target structure and the actual print often occur due to physico-chemical processes, limiting the accuracy and reliability of this technology. To minimize these deviations, we hereby present our latest research in developing different neural networks, targeting the above-mentioned aspect. Our networks are trained on several experimental as well as theoretical datasets and show good results in predicting fabrication deviations and (pre-) correcting 2.5D μ-structures. Hence, we demonstrate, that besides conventional iterative correction methods, neural networks are a promising alternative to significantly improving the output quality in DLW. First directly pre-corrected structures show a reduction of the root mean square error up to 93% in the best case scenario. Furthermore, there are no fundamental limitations to transferring this machine learning approach to other 3D printing technologies, as they all face the same challenge in terms of fidelity. To our point of view, the use of neural networks has the potential to enhance the capabilities of this technology, enabling the creation of complex structures with increased accuracy and precision in the near future.
Published
, Published online: 09 September 2026
, doi: 10.37188/lam.2026.112
Table-top extreme ultraviolet (EUV) reflection ptychography has gained increasing interest in semiconductor metrology due to its nanometer-scale resolution, nondestructive character, and laboratory-scale cost-effectiveness. However, its widespread adoption remains constrained by alignment challenges inherent to grazing-reflection geometry, which have prevented reflective configurations from achieving image quality comparable to those of transmission-mode systems. In this study, we introduce a table-top EUV grazing-reflection ptychography system that enables full-pose self-calibration through holistic system modeling and highly efficient optimization. The developed system is validated using a customized wafer sample and real chip sample. Experimental results indicate that the system successfully corrects image distortions, improves resolution, and enhances surface metrology quality. Furthermore, we discuss algorithmic and physical issues including the feature-domain phase-retrieval for ptychography and coupling effect among pose parameters. The proposed approach not only accelerates the transition of EUV reflection ptychography toward real-world use but also opens avenues for methodological advances to a wider range of imaging applications.
Published
, Published online: 08 September 2026
, doi: 10.37188/lam.2026.090
Phase-shifting interferometry underpins surface topography metrology in precision fields such as semiconductor manufacturing and optical engineering. However, its reliance on stringent vibration isolation and precise phase-shifting control restricts its applicability in many scenarios, particularly in the characterisation of large-aperture optical components. To address these limitations, we present disturbance-introduced interferometry, which harnesses ambient random mechanical disturbances as phase-shifting sources. We also develop a large-disturbance-adaptive natural phase decoding algorithm to reconstruct the surface topography from the resulting interferograms. This framework reduces reliance on stringent vibration isolation and precise phase-shifting control, making it particularly suitable for large-aperture surface metrology and measurements in vibration-prone manufacturing environments. Experimental results demonstrated that even in uncontrolled and vibration-prone environments, the method achieves a root-mean-square wavefront repeatability below 0.0018\begin{document}$ \lambda $\end{document} \begin{document}$ \lambda $\end{document} \begin{document}$ \lambda $\end{document} \begin{document}$ \lambda $\end{document} \begin{document}$ \lambda $\end{document}
Published
, Published online: 07 September 2026
, doi: 10.37188/lam.2026.105
An achromatic metalens (480–640 nm) was designed via integrating propagation and geometric phase principles and fabricated using one-step nanoimprint lithography (NIL). A novel nanoimprint photoresist was used, which not only has a high refractive index (1.92–1.97) and high transmittance (>99%) but also exhibits low shrinkage (≤5.19%). This low shrinkage results in small dimensional deviations of the meta-atoms relative to the NIL master. The working stamp was fabricated in 10 min using an ultraviolet-curable material. This process is much faster than polydimethylsiloxane-based alternatives, which require several hours of thermal curing. Owing to its high fabrication accuracy, the metalens exhibited excellent focusing and achromatic performance, with a wavelength-dependent focal-length deviation of <2%. This study has provided a potential route for the high-precision, high-efficiency, and large-scale production of achromatic metalenses and other nano/micro-optical devices.
Published
, Published online: 01 September 2026
, doi: 10.37188/lam.2026.013
The rapid evolution of high-end technologies demands optical manufacturing with low cost, high efficiency, and superior performance. Existing sub-aperture polishing paradigms rely on a stable tool influence function (TIF) and control material removal by convolving dwell time along the path. However, regulating only dwell time creates an inherent trade-off between removal efficiency and fabrication accuracy, introducing mid-spatial-frequency errors. This paper proposes an innovative manufacturing paradigm based on the immersion depth and scanning speed dynamic co-variation (IDSS-DC) model, establishing an adjustable mechanism for the TIF. A novel dual-degree-of-freedom coordinated control paradigm is developed to simultaneously achieve high efficiency and superior fabrication quality. The influence of immersion depth on removal efficiency is derived, facilitating spatiotemporal control of the TIF in efficiency and profile, allowing optimization of multi-spatial-frequency errors within a single pass. Additionally, a dwell time solution method using constant-variable speed dual-mode (CVSDM) driven by actively controllable spatiotemporally variable TIF (ACSV TIF) accelerates error convergence. Magnetorheological finishing experiments and simulations show that the IDSS-DC model surpasses the traditional paradigm improving accuracy by nearly 10% and reducing processing time by more than 30%. The results demonstrate efficient and stable convergence of multi-spatial-frequency errors, providing an innovative manufacturing paradigm for nanometer-level precision and high-efficiency optical fabrication.
Published
, Published online: 28 August 2026
, doi: 10.37188/lam.2026.121
Structured illumination microscopy (SIM) doubles the lateral resolution compared with wide-field fluorescence microscopy. However, the fast modulation of structured illumination patterns is typically highly dependent on pixelated digital devices, which suffer from low optical efficiency, self-diffraction noise, and high costs. Here, we present a Sector-Rotational SIM (Sero-SIM), which integrates the modulation of the illumination direction and phase shift into a single sector-rotational transmissive grating, achieving an approximately twofold resolution enhancement at a very low cost and minimal control complexity. Moreover, by incorporating a pyramidal lens into the optical setup, we decouple the sector size from the field of view (FOV), expanding the FOV by more than 13 times. We evaluated the performance of Sero-SIM using high-fidelity imaging of diverse subcellular structures in both fixed samples and live cells. The capability of large-FOV super-resolution imaging endows Sero-SIM with a strong potential for applications spanning multiple spatial scales, from pathological tissues and cell populations to single cells and subcellular organelles. Altogether, Sero-SIM introduces a distinctive and practical approach for SIM implementation.
Microcavity-enhanced optoelectronic fiber photoacoustic spectroscopy for ppb-level trace gas sensing
Published
, Published online: 16 April 2026
, doi: 10.37188/lam.2026.028
Photoacoustic spectroscopy is a highly sensitive analytical technique for trace chemical detection in gaseous and liquid phases. Conventional systems relying on free-space optics face limitations in light-matter interaction efficiency and electronic integration. To address this, we developed a miniaturized, ultrasensitive photoacoustic spectroscopy gas sensor by integrating a thermally drawn multi-material optoelectronic fiber, a T-type resonant photoacoustic cell, and a MEMS microphone at the fiber tip. This system enables amplified light-gas interactions and simultaneous electrical signal acquisition, achieving ppb-level detection within seconds using sub-microliter sample volumes (0.02 mL). By leveraging mass-producible optoelectronic fibers and MEMS technology, this work establishes a new class of optical sensors featuring compact size, ultrahigh sensitivity, environmental robustness, and scalable multiplexed detection capabilities for harsh environments.
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.
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