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Published
, Published online: 03 June 2026
, doi: 10.37188/lam.2026.074
With the rapid advances in digital technologies and intelligent manufacturing, three-dimensional (3D) imaging based on fringe projection has laid the foundation for machine vision, industrial metrology, and interdisciplinary applications. This review provides a comprehensive overview of fringe projection profilometry (FPP), which is a widely adopted technology in the 3D imaging landscape. First, we outline the fundamental principles, implementation procedures, and historical developments of FPP. Next, we present the continuous advances in algorithms, hardware, and applications that collectively push FPP towards increasingly challenging measurement scenarios. Subsequently, we provide a dedicated discussion to explain the transformative roles of artificial intelligence (AI) and computational imaging (CI), delineating how their progress is initiating a shift from traditional geometric approaches towards computational 3D imaging. The current challenges and emerging trends in 3D imaging are further identified and discussed. Looking ahead, FPP is expected to evolve into a next-generation 3D imaging technique, achieving unprecedented accuracy, efficiency, and adaptability through the co-optimization of systems with algorithms and the convergence of AI and CI, thereby empowering more complex requirements across industrial, biomedical, and scientific domains.
Published
, Published online: 22 August 2026
, doi: 10.37188/lam.2026.104
Large-aperture telescopes are indispensable tools for astronomical research. Over the past few decades, a host of representative projects have been developed, whose performance relies heavily on the manufacturing and testing technologies for large-aperture mirrors. This paper reviews the state-of-the-art fabrication and testing methods for large optical mirrors and is structured into five parts: application background, classification of manufacturing techniques, overview of metrology technologies, verification and standards, as well as conclusions and future perspectives. Sustained innovation in fabrication and testing lays a solid foundation for technological progress in this field and the implementation of next-generation telescope projects. Key development directions include achieving sub-nanometer-level surface accuracy, boosting large-batch manufacturing efficiency, upgrading metrology equipment and methodologies, and promoting the intelligent and automated integration in fabrication and metrology systems. It is expected that this review will serve as a valuable reference for researchers aiming to gain a full insight into understanding of manufacturing and testing technologies for large-aperture optical components.
Published
, Published online: 10 August 2026
, doi: 10.37188/lam.2026.078
Birefringence refers to the optical anisotropy of transparent media, manifesting as light-wave splitting and phase differences owing to the direction-dependent refractive indices. This phenomenon is closely related to the internal microstructure, stress state, and external fields that affect materials. In recent years, birefringence analysis has gained increasing attention as a powerful tool for revealing the microscopic anisotropic features, polarisation responses, and macroscopic stresses that are difficult to observe using conventional methods. The accurate measurement and characterisation of birefringence in transparent media have become critical in fields such as materials science, biomedicine, and precision manufacturing. This paper provides a comprehensive review of the methods used for birefringence measurement based on polarisation optics. First, it introduces the birefringent polarisation optical theory, mechanisms of birefringence, and classification of the measurement characteristics. Subsequently, common techniques including polarisation modulation analysis, interferometric methods, and other optical approaches are presented in detail, covering their principles, features, advantages, limitations, and applicable scenarios. Recent research advances are also discussed, with an emphasis on applications such as residual stress analysis, characterisation of advanced material anisotropy, pathological diagnosis in biological tissues, and performance evaluation of novel birefringent components. Finally, current challenges are outlined, and future trends in the field are proposed.
Published
, Published online: 28 April 2026
, doi: 10.37188/lam.2026.077
Refractive index (RI) is related to the physical parameters of a sample including morphology and tension. Consequently, three-dimensional RI imaging is critical for many fields. Three-dimensional (3D) RI imaging can be realised by recording transmittance wavefronts of a sample at different illumination angles and using the Fourier slicing or Fourier diffraction theorem to reconstruct the 3D RI image. Currently, advanced label-free 3D RI imaging techniques such as optical tomography and optical diffraction tomography have been increasingly utilised in many fields and demonstrated promising results. To further promote the application of 3D RI imaging technology, this paper provides an overview of the basic principles, experimental implementations, and applications of 3D RI imaging techniques. Further, the performance and characteristics of 3D RI imaging techniques with different illumination strategies and different reconstruction algorithms are compared, and the current trends and future perspectives are discussed. We hope that this review serves as a comprehensive guide to 3D RI imaging for both microscopists and biologists.
Published
, Published online: 06 May 2026
, doi: 10.37188/lam.2026.021
Metrology is a prerequisite for all advanced fabrication methods. For precision optical systems, optical surfaces require form accuracies down to nanometer level-accross areas with lateral dimensions measuring centimeters to decimeters, or even larger for astronomical instrumentation. This poses a challenge specifically for aspheric and freeform surfaces that scientists have tackled ever since the fabrication technologies allow the production of these, from an optics designer point of view, superior surfaces. In this work, we discuss several state-of-art metrology approaches with a focus on calibration. Specifically, we restrict ourselves to interferometric areal methods that have the potential to acquire a dense 2D surface deviation map within a short data acquisition time of less than a minute.
Published
, Published online: 23 March 2026
, doi: 10.37188/lam.2026.035
The relentless pursuit of higher resolution and sensitivity in astronomical observation drives the advancement of telescope mirror manufacturing. This review systematically charts the technological evolution from material innovation to the deterministic control of full-spatial-frequency errors. We analyze the progression of substrate materials—including silicon carbide, beryllium alloys, and advanced glass-ceramics—focusing on their critical thermomechanical properties for extreme environments. The core manufacturing chain is thoroughly examined: ultra-precision diamond turning for initial form generation, grinding processes exploiting brittle-to-ductile transitions, and advanced polishing techniques like magnetorheological finishing and ion beam figuring that achieve nanometer-level accuracy. A central theme is the paradigm shift towards segmented mirrors, which necessitates solving system-level challenges in edge control, co-phasing, and high-consistency batch production. The integration of field-assisted machining and intelligent systems, such as digital twins and robotics, is highlighted as a key enabler for next-generation manufacturing. While significant progress is evident, core challenges persist in stable sub-nanometer finishing, subsurface damage mitigation, and long-term performance under operational extremes. Future development hinges on deeper material-process co-design, fully integrated metrology-manufacturing loops, and sustainable production frameworks. This synthesis provides a comprehensive technical foundation for developing the extreme optical systems required for future discoveries in astrophysics.
Published
, Published online: 19 March 2026
, doi: 10.37188/lam.2026.001
Precision aspherical lenses are in high demand for a wide range of industrial and consumer products. While plastic lenses have gained popularity for low cost and flexibility, glass remains the superior material for high-end optics for its exceptional optical properties. Glass molding is a modern manufacturing technique that offers both high precision and affordability. This review, aimed at both academic and industrial communities, provides a brief history of this technology followed by a detailed discussion of the fundamental physics and modeling involved in the molding process. The review also includes a brief discussion of optical design and forming equipment but focuses on the molding process. In addition to conventional methods, we also cover special molding techniques like rapid heating and wafer-level glass molding, as well as the molding of chalcogenide glass lenses. By examining key developments in material modeling, mold fabrication, heat transfer and process optimization, this review aims to support ongoing advancements for next-generation precision optical manufacturing processes.
Published
, Published online: 12 October 2025
, doi: 10.37188/lam.2025.055
High-power laser coatings play a critical role in enabling optical manipulation in various laser applications, including beam alignment and control in high-power laser systems. These coatings rely on multilayers and microstructures, such as antireflective (AR) and highly reflective (HR) coatings, filters, and beam splitters, to enhance their performance. This review focuses on laser coatings used for manipulating optical fields, their principal limitations, and laser-induced damage in high-power applications. The concepts, principles, and progress made in exploring the optical performance and distinctive functions of the optical coatings and optimising the laser resistance through structural optimisation, material engineering, and defect elimination are highlighted. Finally, future directions for improving the design flexibility, fabrication feasibility, advanced detection techniques for high-resolution defect characterisation, and further consideration of minimising the optical loss are discussed to meet the evolving demands of modern high-power laser systems.
Published
, Published online: 03 September 2025
, doi: 10.37188/lam.2025.059
Meta-devices, known for their capability to manipulate light fields at a subwavelength scale, have gained significant traction in the realm of quantum photonics in recent years. They are being utilized in miniaturized applications such as the preparation of quantum light sources and the control and detection of quantum states. In this review, we provide a systematic explanation of the working principles and notable applications of meta-devices in quantum optical information processing, while also outlining potential directions for the future development of quantum meta-devices.
Published
, Published online: 21 August 2025
, doi: 10.37188/lam.2025.058
Although terahertz (THz) spectroscopy and imaging offer a variety of applications in medical diagnosis of malignant and benign neoplasms, their translation into clinical practice is hampered by the absence of endoscopic systems capable of sensing the THz optical properties of the hard-to-access tissues. In this review, we focus on recent attempts to address this challenge. To better highlight the need for THz endoscopes, we start with a brief overview of THz medical applications, with an emphasis on neoplasms diagnosis. We then consider the two existing principles of THz endoscopy. The first uses the fiber-coupled THz photoconductive antennas (PCAs) for the THz generation and detection in close proximity to a hard-to-access object, where optical fibers are applied to flexibly deliver the laser pump and probe beams to the THz emitter and detector. The key technology of the second approach is the THz optical fibers capable of delivering the THz waves to an analyte and then detecting the reflected and back-propagated THz signal. Despite this approach still lacking the efficient commercially available THz fiber optics, most recent developments pave the way to solve these problems. In this review, several notable examples of THz endoscopic systems based on different guiding mechanisms, material platform, and manufacturing strategies are discussed.
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