Search Results (77)

Reflective SLMs are gaining increasing attention for aspherical surface testing due to their dynamic adjustability, fast operation, and high optical efficiency, offering clear advantages over costly CGH methods. This paper presents a wavefront measurement system that avoids the need for dedicated beam-splitting or complex long optical paths typically required when using a reflective SLM in the interference section. The measured results are comparable to those obtained with a commercial lens compensation method, with the overall RMS values agreeing to within approximately 0.01λ, and the maximum RMS deviation from the mean remaining within 0.025λ across all temperature conditions. With its simple structure and short optical path, the system enables fast measurement. Full article

Segmented primary mirror technology overcomes the manufacturing limitations of large-aperture monolithic mirrors by assembling the primary mirror from multiple off-axis aspheric sub-mirrors. However, null testing of such off-axis aspheric surfaces with a compensator introduces mapping distortion, which prevents the interferometric data from directly guiding high-precision deterministic figuring. This paper proposes a mapping distortion correction method for sector-shaped off-axis aspheric sub-mirrors tested with a null lens. The method exploits the fact that one-dimensional radial distortion symmetry of the null lens about its distortion center. First, the distortion center coordinates are determined from the radial boundary data of the distorted interferogram of the sector-shaped mirror. Then, an error function is constructed based on the deviation of the measured outer-to-inner radius ratio of the sector-shaped mirror from its nominal value, and the radial distortion coefficients are iteratively solved using a radial distortion model refined by a sparse set of fiducial marks. Finally, the mapping distortion is corrected through an inverse mapping with solved distortion center coordinates and radial distortion coefficients. The proposed method was validated on a sector-shaped sub-mirror with outer and inner radii of 357.5 mm and 75.5 mm, reducing the outer-to-inner radius ratio error from 0.3833 to 0.0094, with a maximum fiducial coordinate deviation of 0.91 mm. Based on the distortion-corrected map, a single deterministic figuring run reduced the surface figure RMS from 0.034λ to 0.025λ (λ = 632.8 nm), demonstrating the effectiveness of the method. Full article

Despite the widespread use of orthokeratology (ortho-k), the diurnal behavior of corneal geometry after lens removal remains unclear. This prospective observational study evaluated diurnal variations in corneal geometry, refractive error, and visual performance in ortho-k wearers using global and sector-based corneal analyses. Nineteen eyes from ten ortho-k wearers were examined at five time points over a 10-h period following overnight lens wear. Corneal thickness, anterior and posterior corneal curvature, corneal asphericity, autorefractometry, and visual acuity were assessed. Corneal elevation data were reconstructed using Zernike polynomial expansions, and regional analyses were performed using concentric annular sectors. Diurnal amplitudes were compared with a healthy control cohort evaluated using the same protocol. Corneal thickness progressively decreased throughout the day (p < 0.001). Anterior corneal curvature showed progressive steepening (p ≤ 0.011), whereas posterior corneal curvature exhibited significant flattening (p ≤ 0.018). A progressive myopic refractive shift was also observed, with a spherical equivalent amplitude of −1.03 D (p = 0.002). Despite these changes, visual acuity remained stable (p = 0.248). Compared with healthy controls, ortho-k wearers showed greater amplitudes of central corneal thickness and anterior corneal curvature changes. These findings indicate that ortho-k may enhance normal diurnal corneal changes while maintaining visual acuity. Full article

When designing lens systems for optical sensors, a fundamental operation is finding the intersection of a ray and the lens surface. We propose a robust method for finding the intersection of a ray with highly aspherical rotationally symmetric surfaces. Our method provides reliable results for ray incident at large angles relative to the optical axis and successfully calculates intersection points for a significantly larger number of rays than existing methods, improving the reliability of optical modeling and design. The core idea of our method is to calculate an initial approximation of the intersection point for the Newton method using a ray marching procedure with a step size estimated form of analytical derivatives on the surface function. The proposed method does not require maintaining additional complex data structures and is suitable for use in the iterative optimization of optical systems where the surface geometry frequently changes. Full article

As the prevalence of myopia among adolescents continues to increase, the design and fabrication of myopia control lenses have become an important research direction in modern optics. Existing myopia control lenses mostly adopt purely refractive structures, which suffer from limited design freedom, insufficient chromatic aberration suppression, and relatively large lens thickness, thereby restricting further improvement of optical performance. This paper proposes a refractive–diffractive hybrid design and fabrication method for myopia control lenses. Centered on a harmonic diffractive optical element (HDOE), an optimization model is established to balance achromatization performance and fabrication feasibility. To address the challenges of small period width, tool shadow effect, and sensitivity to machining tolerances in diffractive lenses with large-aperture and high-additional-power, harmonic design is employed to increase the period width, thereby reducing fabrication difficulty and mitigating the influence of shadowing errors on diffraction efficiency. On this basis, two lenses with different phase structures are designed: one adopts a conventional diffractive correction phase to verify the role of HDOE in achromatization and edge-thickness reduction, while the other adopts a high-degree-of-freedom smooth phase to achieve a continuous multifocal visual effect. Both lenses are fabricated by single-point diamond turning (SPDT), and the effects of surface profile and machining parameters on performance are analyzed. Simulations and measurements show that the proposed method provides stable diffraction efficiency and effective chromatic aberration correction across the design band, while reducing the edge thickness by approximately 37.85% without additional thinning of the aspheric substrate. The results indicate that the refractive–diffractive hybrid design provides a feasible design and fabrication approach for functionally more complex myopia control lenses. Full article

Ultrahigh lateral resolution (UHLR) optical coherence tomography (OCT) technology, also called optical coherence microscopy (OCM), has gained popularity, especially in the field of biomedical imaging. In these systems, high numerical aperture (NA) Microscope objectives (MO) are employed in OCM systems to offer better than 3 µm lateral resolution. However, in the implemented broadband OCM configuration, the use of complex multi-element microscope objectives can reduce the detected returned signal compared with a simpler imaging lens configuration. This reduction in detected returned signals can become an important practical limitation in many OCM applications, particularly for biomedical imaging when high imaging speed is crucial. This study investigates whether a single off-the-shelf lens can provide a practical alternative to conventional MOs, achieving higher throughput while maintaining reasonable spatial resolution. We systematically evaluated 14 commercial lenses using Zemax OpticStudio simulations, identifying an aspherized achromatic lens (Edmund Optics #85302) that best met these key criteria. To validate its feasibility for OCM, performance was tested in both Full-Field Time-Domain OCM (FF-TD-OCM) and Line-Field Spectral-Domain OCM (LF-SD-OCM) configurations. Using a broadband composite Superluminescent Diode (SLD) source (750–920 nm), we quantified the resolvable features, axial resolution, and overall light transmission. The validated system demonstrated near-diffraction-limited performance. In the LF-SD-OCM setup, it successfully resolved features as fine as Group 8, Element 6, corresponding to a 2.2 µm line pair pitch (~1.1 µm line width) and achieved a 2.86 µm axial resolution in air. A through-focus comparison further showed practically useful contrast retention around focus. Additional imaging of onion epidermal tissue and ex vivo porcine corneal tissue demonstrated that the proposed lens could provide interpretable structural images on representative biological samples. Under the tested LF-SD-OCM detection configuration, the selected lens delivered approximately 2.0 dB higher returned signal than the Mitutoyo MY10X-823 objective according to 1.59× larger received signal. Full article

Designing high-speed wide-angle optics for large-format mirrorless cameras presents a fundamental engineering conflict between the short flange back distance and the requirement for high-resolution aberration correction. To address this challenge, this study proposes a compact 18.5 mm F/2.0 lens system utilizing a modified retrofocus architecture equipped with an internal floating-focus mechanism. The design methodology integrates glass-molded aspherical surfaces to suppress high-order aberrations and employs passive athermalization strategies to maintain stability across a temperature range of −30 °C to +70 °C. Performance was rigorously evaluated using numerical simulations in Zemax OpticStudio, alongside comprehensive Monte Carlo tolerance analysis. Simulation results demonstrate exceptional optical performance, with the Modulation Transfer Function (MTF) exceeding 0.5 at a spatial frequency of 100 lp/mm across the field. Furthermore, focus breathing is restricted to less than 1%, and optical distortion is strictly controlled within 2%. The Monte Carlo tolerance analysis predicts a manufacturing yield exceeding 80% under standard industrial precision levels. Ultimately, this work provides a theoretically sound, athermally stable, and highly manufacturable solution suitable for next-generation high-resolution mirrorless sensors. Full article

This paper presents a systematic investigation into the design and performance of layered polymer gradient refractive index (GRIN) lenses. A material-driven optimization algorithm is proposed, which uses physical volume fractions of the constituent polymers to parameterize the refractive index distribution. By integrating effective medium theory with Sellmeier-based dispersion data, the algorithm ensures that the gradients remain within physically realizable material limits while better aligning with actual refractive index profiles. First, refractive index distribution models for first-order radial GRIN lenses and linear spherical radial GRIN lenses were derived based on material properties, establishing manufacturable lens parameterization expressions. Subsequently, simulation software was employed to model and compare a first-order GRIN doublet, a cemented doublet, a linear spherical radial GRIN lens, and a first-order GRIN aspheric lens. Numerical results demonstrate that the proposed GRIN structures exhibit superior performance in both monochromatic aberration suppression and chromatic control, particularly under large aperture conditions. For a lens system with a 50 mm focal length and a 25 mm entrance pupil diameter, the spherically symmetric GRIN lens achieves diffraction-limited chromatic performance, with its secondary spectrum reduced by over 70% compared to conventional cemented doublets. Furthermore, the first-order GRIN doublet maintains the smallest RMS spot size across multiple fields of view and exhibits the most stable aberration growth rate as the aperture increases. These results validate the feasibility of the material-driven GRIN modeling approach and provide theoretical support for high-performance, short-focal-length optical systems. Full article

Background: This study examined spherical and aspherical orthokeratology (Ortho-K) lens designs for myopia control and corneal optical stability over the course of a year. Methods: This retrospective analysis used data from a previously conducted two-centre, single-blind, randomised contralateral-eye clinical study, in which 48 children aged 8 to 15 years wore a spherical Ortho-K lens in one eye and an aspherical lens in the other. Measurements included axial length (AL), best-corrected visual acuity (BCVA), lens decentration, corneal power, and higher-order aberrations over 12 months. Corneal topography was analysed using customised MATLAB code, Zernike fitting and paired inter-eye differences were evaluated with the Wilcoxon signed-rank test. Results: Both lenses exhibited typical Ortho-K reshaping patterns, with central flattening and mid-peripheral steepening. The aspherical lens resulted in slower AL elongation than the spherical lens (p < 0.01). It also produced smaller, more stable treatment zones and less variability in higher-order aberrations. Significant differences between the designs were found for vertical coma (p = 0.006), spherical aberration (p = 0.002), and vertical tilt (p = 0.02). Lens decentration also differed significantly (p < 0.01). Conclusions: Over 12 months, the aspherical Ortho-K lens demonstrated superior myopia control and more stable corneal optics than the spherical lens. Full article

This article investigates fiber coupling techniques for low numerical aperture 808 nm semiconductor lasers. A coupling optical system combining fast-axis/slow-axis collimators (FAC/SAC) with a focusing lens was designed, achieving efficient coupling through high-precision optical integration packaging. First, a high-power GaAs-based 808 nm semiconductor laser chip was designed and fabricated. Its thermal performance and operational stability were enhanced by optimizing packaging materials and structures. The coupling system employs a fast-axis collimating lens, slow-axis collimating lens, and aspheric focusing lens to shape the beam and focus it into a 200 μm/0.12 NA fiber. Experimental results show that the developed coupling module achieves the threshold current of 1.2 A at 298 K, the continuous output power of 9.59 W, with the slope efficiency of 1.1 W/A, a coupling efficiency of 95%, the maximum output numerical aperture of 0.116, the wavelength temperature drift coefficient of approximately 0.2 nm/°C, and the peak brightness of 0.72 MW/cm²·sr. This study validates the feasibility and superiority of the FAC/SAC combined with focusing lens approach for low-NA fiber coupling. It provides theoretical and practical foundations for fiber coupling in high-brightness, high-power laser systems, offering promising applications in solid-state laser pumping, enhancing system integration, and enabling long-distance, high-brightness transmission. Full article

Background/Objectives: Premium intraocular lenses (IOLs) are increasingly being selected for cataract and refractive lens surgery, but their functional performance depends critically on pupil size and corneal spherical aberration (SA). This study evaluates how these factors modulate the optical behavior of the RayOne EMV and Tecnis Synergy using a profilometry-based Through Object modulation transfer function (TO MTF) analysis. Methods: The surface profiles of the RayOne EMV and Tecnis Synergy were measured with a confocal optical profilometer and implemented in pseudophakic eye models via ray tracing. TO MTF at 50 cycles/mm was computed for object vergences from −4.0 D to +2.0 D over entrance pupil diameters from 2.0 to 5.5 mm in three corneal configurations derived from the Liou–Brennan model and ISO recommendations: mean population SA, aberration-free, and a myopic LASIK-like oblate cornea. Simulated optotype images were generated to relate TO MTF values to the expected distant, intermediate, and near visual performances. Results: RayOne EMV delivered high-quality distant image performance in all models. Its depth of focus increased only modestly and showed a strong dependence on pupil size. Intermediate and near vision rarely reached clinically acceptable levels. The Tecnis Synergy produced a broad depth-of-field plateau in distant to near visual performance for mean population spherical aberration at a 3.5 mm pupil. However, image quality at 90 cm remained limited. Optical performance worsened with increasing pupil size and positive spherical aberration, particularly under post-myopic LASIK conditions. Conclusions: The RayOne EMV behaves predominantly as a distance-oriented design with minimal true presbyopic benefit; the Tecnis Synergy provides a wider range of vision but is highly sensitive to corneal spherical aberration and pupil size, so thorough preoperative evaluation of corneal asphericity and functional pupil diameter is essential for IOL selection and power targeting. Full article

This study presents the design and optimization of a digital-imaging afocal telescope system that integrates an afocal telescope architecture with an imaging optical subsystem. The proposed system employs a combination of spherical and aspherical optical elements to enhance imaging flexibility, reduce aberrations, and ensure effective system coupling. Proper pupil matching is achieved by aligning the exit pupil of the afocal telescope with the entrance pupil of the imaging system, ensuring minimal vignetting and optimal energy transfer. Circular apertures and lens elements are used throughout the system to simplify alignment and minimize pupil-matching errors. The complete system comprises three imaging optical subsystems and a digital camera module, each independently optimized to ensure balanced optical performance. The design achieves an overall magnification of 16×, with near-diffraction-limited quality confirmed by an RMS wavefront error of 0.0474λ and a Strehl ratio of 0.915. The modulation transfer function (MTF) reaches 0.42 at 80 lp/mm, while the distortion remains below 4.87%. Chromatic performance is well controlled, with maximum lateral color deviations of 1.007 µm (short-to-long wavelength) and 1.52 µm (short-to-reference wavelength), evaluated at 656 nm, 587 nm, and 486 nm. The results demonstrate that the proposed digital-imaging afocal telescope system provides high-resolution, low-aberration imaging suitable for precision optical applications. Full article

This study presents an optical and thermal design for a compact 10× periscope zoom lens suitable for smartphones, employing a hybrid thermal compensation scheme to ensure stable imaging performance over a wide range of temperatures. Our proposed zoom optics system integrates passive and active compensation mechanisms, further enhancing thermal stability through the use of a curved image sensor. Passive compensation is achieved through the selection of low-G optical materials and an optimized structural configuration. In contrast, active compensation dynamically adjusts the zoom group position in response to changes in ambient temperature. Optical simulations confirm that this 10× periscope zoom lens, composed of a prism, eight aspherical lenses, and two parallel plates, maintains diffraction-limited resolution and less than 2% distortion at all zoom positions (Zoom 1 to Zoom 6), achieving a total depth of 4.96 mm. Thermal analysis at temperatures ranging from −20 °C to 60 °C demonstrates that the optimized design, utilizing a curved sensor (Design type 3), achieves an average MTF of 0.58 and an average degradation rate of only 12.8%, exhibiting excellent non-thermal performance. These results highlight the effectiveness of the proposed novel hybrid thermal compensation strategy and surface sensor integration in realizing high-magnification, thermally stable periscope optics for next-generation smartphone imaging systems. Full article

Myopia prevalence has risen dramatically worldwide, underscoring the critical need for effective interventions to slow its progression. Recent advancements in spectacle lens technology offer promising solutions, demonstrating significant efficacy in controlling myopia. This review critically examines next-generation spectacle lenses for myopia management, emphasizing their optical principles, mechanisms of action, clinical effectiveness, visual performance, compliance, and safety. Spectacle lenses incorporating technologies such as Defocus Incorporated Multiple Segments (DIMS), Highly Aspherical Lenslet Target (HALT), Diffusion Optics Technology (DOT), and Cylindrical Annular Refractive Element (CARE) lenses show a 40–60% reduction in refractive progression and axial elongation compared to traditional single-vision lenses. These lenses utilize optical strategies like simultaneous myopic defocus, peripheral contrast modulation, and controlled aberrations without compromising visual acuity, contrast sensitivity, accommodation, or binocular vision. High wearer compliance is attributed to excellent visual comfort, minimal adaptation issues, and favorable cosmetic appearance. Long-term studies further confirm sustained efficacy and safety profile. Ongoing research aimed at direct comparative trials, extended follow-up, and individualized lens designs will further define the role of these interventions. Collectively, the evidence positions next-generation spectacle lenses as a promising, evidence-based approach that may become an important component of global myopia management. Full article

Designing a compact collimating lens system for augmented reality (AR) applications presents significant optical challenges. This paper presents a compact, 50-degree field-of-view collimating lens system explicitly designed for lightguide-based AR glasses. The compact collimating lens is designed for a 0.32-inch microdisplay and consists of four plastic aspherical lenses. The optical design results in a collimating lens with a F-number of 2.17 and an entrance pupil diameter of 4 mm. Optical distortion is less than 0.29%, and the modulation transfer function (MTF) is greater than 0.23 at 250 cycles/mm. The overall lens diameter, including the lens barrel, measures 10.16 mm, while the lens length is 11.48 mm. The lens volume is 0.93 cm³, and its mass is 1.08 g. Compared to existing collimator designs, this approach significantly improves the trade-off between field of view, optical quality, and device miniaturization. The proposed design supports integration with 0.32-inch microdisplays, making it a practical and manufacturable solution for next-generation AR eyewear. This paper presents innovative contributions to the optical design of AR glasses, demonstrating considerable potential in reducing size and weight, and optimizing optical performance. Full article