Category: Blog

A recent study involving over a thousand children aged 8 to 15 has investigated the effectiveness of different orthokeratology (OK) lens designs in controlling myopia, also known as nearsightedness. Myopia is a growing global concern, predicted to affect nearly 50% of the world’s population by 2050. OK lenses are special contact lenses worn overnight to reshape the cornea and improve daytime vision without glasses or regular contacts, and they are also used to slow down myopia progression in children.

Researchers at several eye hospitals in China compared two main types of OK lens designs: Corneal Refractive Therapy (CRT) lenses and Vision Shaping Treatment (VST) lenses. VST lenses, including brands like Euclid, Alpha, and Hiline, are designed with multiple curves, while CRT lenses are designed with fewer curves. The study followed children wearing one of these four lens types for a year and a half, tracking changes in their refractive error, axial length of the eye (a key measure of myopia progression), and any adverse events.

The study found that while both types of lenses are generally safe, VST lenses demonstrated better efficacy in slowing down myopia progression compared to CRT lenses. Children wearing CRT lenses showed a faster increase in axial length and a higher rate of myopic progression, meaning their nearsightedness worsened more quickly. Specifically, axial length elongation was significantly less with VST lenses. Around 37% of children using CRT lenses experienced fast myopia progression, compared to 20-30% with VST lenses.

Interestingly, CRT lenses showed a slightly better safety profile with a lower overall incidence of adverse events, particularly less corneal staining. Researchers believe this might be related to the material and design of CRT lenses, which may allow for better oxygen permeability to the cornea.

The study suggests that the design of OK lenses can influence how effective they are in controlling myopia. VST lenses, with their multi-curve design, appear to be more effective at slowing myopia progression in children compared to CRT lenses. However, CRT lenses may offer a slight advantage in safety. The findings highlight the importance of personalized lens design in orthokeratology and suggest that further research is needed to optimize lens designs for better myopia control and safety. The study also points to factors like the treatment zone diameter and compression factor of the lenses as potential reasons for the observed differences in efficacy. Experts emphasize that while OK lenses are generally a safe option, careful consideration should be given to lens design and individual patient needs when choosing a myopia management strategy.

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Optical and mechanical engineers face significant hurdles when collaborating to transform optical system designs into tangible products, often encountering costly and error-prone transitions between their respective design phases. Integration challenges arise from the use of separate software environments, hindering seamless communication and workflow. While optical engineers have seen advancements in their toolsets, mechanical engineers have lacked adequate tools to analyze and validate how mechanical geometry impacts optical performance, assess optomechanical tolerances, optimize mechanical designs across different configurations, or conduct structural and thermal deformation analysis.

Robert Mentzer, an optical engineer at Global Surgical Group, noted difficulties in communication during the handoff process between optical and mechanical design, leading to delays, design iterations, validation bottlenecks, and the expensive production of physical prototypes to identify problems.

A major issue lies in preserving the integrity of optical data when transitioning to mechanical designs. The common practice of importing optical systems as STEP, IGES, or STL files into mechanical design software like SOLIDWORKS, along with relying on ray bundles for approximating light propagation, introduces inaccuracies. These file formats degrade the precision of optomechanical designs, leading to loss of optical tolerances, coating specifications, and material data. Ray bundles, used as static sketches, represent only a small portion of the actual rays and cannot dynamically update with design changes. Furthermore, mechanical engineers often rely on optical engineers for validation or resort to time-consuming and costly physical prototypes to uncover design flaws.

Mechanical engineers also struggle to efficiently verify if mechanical geometry alterations affect optical performance. Even minor changes or data inaccuracies can significantly impair optical functionality. When mechanical engineers send STEP files back for optical validation, challenges arise from inconsistent coordinate systems and lost design details, requiring optical engineers to manually reconstruct assemblies in their software. This often pushes teams to use less precise methods like screenshots or physical prototypes for validation, which can lead to errors, increased costs, and schedule disruptions.

Mechanical engineers require simulation and analysis tools that expose crucial lens data, such as edges and apertures, as construction geometry. Common problems in optomechanical designs, such as stray light and vignetting caused by beam clipping, are often managed using crude methods like paint or secondary components. Dave Rook, a mechanical engineer at CSA Group, emphasized the substantial expense of not addressing these issues correctly from the outset.

To address these challenges, Zemax has introduced LensMechanix, a simulation software incorporated as a SOLIDWORKS add-in. This tool aims to streamline optomechanical product development by integrating the core physics of Zemax’s OpticStudio software directly into the SOLIDWORKS environment.

LensMechanix simulates light interaction with physical objects through non-sequential ray tracing, factoring in mechanical components and surface finishes to pinpoint design problems like spot size issues, stray light, and image contamination. By loading OpticStudio files into LensMechanix, mechanical engineers can utilize precise lens data to design mechanical components and then simulate light propagation to confirm that the optomechanical design maintains optical performance.

If ray tracing identifies any issues, LensMechanix provides tools like ray filtering and surface power analysis to pinpoint the source, isolate problematic mechanical features, and quickly assess design variations’ impact. It allows visualization of mechanical design changes, quantification of their effect on image quality and performance, comparison against the original optical design, and validation that the solution meets optical requirements.

By using LensMechanix, optical engineers can receive design files with complete fidelity, allowing for efficient review of changes in OpticStudio to ensure packaging does not negatively affect their designs, thereby optimizing production workflows.

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Myopia, commonly known as nearsightedness, is a growing global concern, with prevalence rates projected to increase significantly in the coming decades. Recent research highlights ongoing efforts to manage and control myopia progression, particularly in children and young adults. One promising avenue involves the use of specialized contact lenses designed to slow down the worsening of nearsightedness.

Studies have examined various types of contact lenses, including multifocal soft contact lenses and orthokeratology lenses, for their effectiveness in myopia control. Multifocal contact lenses, which have different power zones to correct vision at various distances, have shown potential in slowing myopia progression compared to traditional single vision lenses. Orthokeratology, or ortho-k, involves wearing specially designed rigid gas permeable contact lenses overnight to reshape the cornea, aiming to reduce or eliminate the need for glasses or regular contact lenses during the day and also potentially slowing myopia development.

Researchers are investigating how these lenses work to control myopia. Theories suggest that they may influence peripheral refraction, accommodation (the eye’s focusing ability), and other visual factors that play a role in eye growth and myopia development. Clinical trials and studies have been conducted to assess the long-term efficacy and visual performance of these myopia control contact lenses.

While these specialized contact lenses offer a potential strategy for managing myopia, ongoing research continues to explore and optimize their design, application, and long-term effects. Eye care professionals play a crucial role in assessing individual needs and recommending appropriate myopia management strategies, which may include contact lenses, spectacle lenses, and lifestyle modifications.

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Researchers have developed a new software toolkit, named RHYTHM, designed for panoramic optical imaging of the heart. This innovative tool facilitates comprehensive three-dimensional visualization and analysis of cardiac electrical activity.

The RHYTHM toolkit operates on standard software platforms, requiring LabVIEW (version 14 or later) and MATLAB (version 2016b or later), alongside a compatible C compiler. For optimal performance, recommended hardware includes an Intel Core i5-2500K 3.3 GHz processor or equivalent, an AMD Radeon 2 GB graphics card or similar, at least 16 GB of RAM, and a minimum of 1 TB of storage space.

The software architecture of RHYTHM is structured into modules addressing geometry reconstruction, optical signal processing, and data visualization. LabVIEW is utilized for heart rotation control following optical mapping, while MATLAB-based graphical user interfaces (GUIs) guide users through camera calibration, surface reconstruction, and optical data projection and analysis. These GUIs are designed for user-friendliness, incorporating semi-automated routines to streamline data processing.

The system employs a detailed camera calibration process to ensure accurate pixel-to-geometry correspondence. This involves using a cuboid with known dimensions and a grid pattern, imaged by both geometry and optical cameras. A custom MATLAB GUI assists in this calibration, identifying and labelling grid intersections and allowing for adjustments in non-ideal imaging conditions.

Surface generation is achieved by capturing silhouette images of the rotating heart. A custom LabVIEW program controls the rotation, and a MATLAB GUI processes these images to reconstruct the 3D heart geometry using an occluding contour method and octree algorithm. This results in a detailed triangular mesh representing the heart’s surface.

The software then projects optical mapping data onto this 3D heart model through texture mapping. A final MATLAB GUI facilitates this projection, along with data processing steps including noise reduction and spatial filtering. This interface allows researchers to visualize the heart surface with mapped electrical activity, offering various viewing options and angles.

Validation of the RHYTHM toolkit has been conducted using rabbit, rat, and mouse hearts. Experiments demonstrated its ability to accurately map the spread of electrical activity in paced heartbeats and analyze complex arrhythmia patterns like ventricular fibrillation. The software’s visualization tools allowed for detailed examination of activation sequences and action potential duration across the entire heart surface.

The RHYTHM toolkit provides a valuable resource for cardiac research, enabling researchers to gain deeper insights into the 3D dynamics of heart function and electrical disorders. The integrated software and hardware framework offers a user-friendly approach to panoramic optical mapping and analysis, potentially accelerating advancements in our understanding and treatment of heart diseases.

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Researchers have developed a novel inverse design method for creating advanced meta-optics, marking a significant departure from traditional forward design approaches. This new framework starts with a desired optical goal, such as maximizing light intensity at a focal point, and then optimizes the design of a metasurface to achieve this goal under given constraints. This is particularly beneficial for designing complex lenses, including polychromatic lenses that focus multiple wavelengths of light simultaneously.

A key component of this method is a fast and accurate simulation tool. The researchers introduced a three-dimensional approximate solver which rapidly evaluates the performance of meta-optics designs. This solver is based on pre-calculated local field data and a surrogate model, making it significantly faster than traditional rigorous simulation methods.

To handle the complexity of optimizing designs with thousands of parameters, the team employed a gradient-based optimization technique along with an adjoint method. This approach efficiently calculates the necessary gradients for optimization, dramatically speeding up the design process compared to brute-force methods.

Using this inverse design framework, scientists successfully engineered and fabricated several large-scale, high-performance metalenses. They demonstrated a 2-millimeter diameter RGB-achromatic metalens that is polarization-insensitive, meaning it focuses light of any polarization state equally well across red, green, and blue wavelengths. Experimental results confirmed its near-perfect achromatic focusing and diffraction-limited performance.

Building upon this success, the team created a polychromatic metalens capable of focusing six different wavelengths across the visible spectrum. They fabricated both 2-millimeter and centimeter-scale versions of these metalenses, showcasing the scalability of their design method and fabrication process. These larger metalenses also maintained high focusing performance.

The researchers highlighted the advantages of inverse design over conventional forward design, especially for complex optical functions. Forward design struggles when multiple objectives need to be met simultaneously, and often neglects the interplay between different design parameters. In contrast, inverse design optimizes directly for the desired outcome, balancing various factors and achieving superior performance.

To demonstrate the practical impact of their work, the researchers integrated their centimeter-scale RGB-achromatic metalens into a virtual reality (VR) imaging system. This system, utilizing a laser-illuminated micro-LCD and the meta-optic lens as an eyepiece, projected high-resolution images, including both static images and dynamic video, showcasing the potential of meta-optics to revolutionize VR technology by enabling compact and high-performance headsets.

This new meta-optics approach offers significant improvements for VR applications and beyond, including increased aperture size, polarization insensitivity, simplified meta-atom geometries for easier manufacturing, and the ability to display dynamic content. The researchers believe that further development of meta-optics will lead to advanced, aberration-free hybrid eyepieces for VR and augmented reality (AR) systems and open new possibilities for various optical technologies.

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Driven by the ever-increasing demand for faster network speeds, Huawei Technologies Canada is innovating optical components, specifically photonic switches, using silicon photonics. For data routing in optical networks, current methods involve converting optical signals to electrical signals for switching, and then back to optical. This conversion process is power-intensive and introduces delays. Photonic switches offer a solution by manipulating signals in their optical form, promising faster speeds and better energy efficiency. However, existing photonic switches tend to be bulky, expensive, and complex to assemble. To overcome these limitations, Huawei is developing integrated optical circuits utilizing silicon photonics technology. These optical circuits, built in standard CMOS chip manufacturing facilities, feature miniaturized silicon waveguides. Huawei engineers are creating highly complex silicon photonics circuits, employing advanced design tools and iterative prototyping to optimize performance, particularly the thermal behavior of their thermo-optic switches. The core of Huawei’s innovation is a thermo-optic switch based on the Mach-Zehnder interferometer. This switch, with “cross” and “bar” states, redirects light by thermally inducing a phase shift within the interferometer. A tiny heater, made of titanium nitride, is integrated into the switch to precisely control the temperature of a waveguide arm. By heating this arm, the refractive index changes, causing a phase shift that toggles the switch state and thus alters the path of light, directing data to different destinations. A key feature of Huawei’s design is a triple-folded waveguide, which amplifies the interaction between the heater and the waveguide, significantly improving the switch’s energy efficiency. This silicon photonics technology is poised to enhance optical networks, making them faster, smaller, and more energy-efficient, crucial for applications like data centers and high-performance computing.

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Optical engineer Bruce H. Walker reflects on his career spanning over five decades, commencing in 1962 at General Electric (GE) in Scranton, Pennsylvania. Starting as an engineering technician under senior optical engineer Don Kienholz, Walker’s early work involved using then-cutting-edge computer systems with specialized lens design software developed for IBM.

Walker recalls his first design project, an infrared objective lens for an IR video sensor, specified for a 1.05 µm wavelength and utilizing a Petzval lens form. The project, completed over three months, contrasts sharply with modern capabilities. In 1964, while numeric data was computer-generated, designers like Walker had to manually draw lens designs and Modulation Transfer Function (MTF) plots, tasks that now take seconds with contemporary PC software.

His tenure at GE extended until 1971, including a move to Syracuse, New York, and broadened his design work to encompass head-up displays, helicopter gunsights, star sight optics, and medical x-ray objective lenses. During this period, Walker also began his writing career, publishing his first article in Optical Spectra in 1968, which led to numerous publications and books.

Following GE’s decision to discontinue its lens design subgroup, Walker joined Kollmorgen Corp. in Northampton, Massachusetts, for 20 years. There, he designed optical systems for military gunsights, submarine periscopes, and head-up optics for aircraft, while also mentoring younger engineers and eventually managing the Optical Engineering Group.

In 1991, Walker transitioned to an optical engineering consultant, a career he has pursued for 25 years. His consultancy expanded his expertise into visual optics, eyepiece design, and 3D stereo optical systems, alongside his established lens design work.

Throughout his career, Walker witnessed the transformative evolution of computer hardware and optical design software. He progressed from customized IBM software to ACCOS, Code III to Code V, and later, OSLO software. He recounts rediscovering the data for his first lens design in 2015 and redesigning it using modern software in just four hours, a stark contrast to the original months-long process. This redesign notably simplified the lens by eliminating a field-flattening element while improving image quality.

Walker emphasizes the symbiotic progress of computer technology and his professional journey, noting that his development as a lens designer was intrinsically linked to these technological advancements.

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Researchers have successfully demonstrated the optimal design for a transparent contact structure using Molybdenum Trioxide (MoO3), Silver (Ag), and Tungsten Trioxide (WO3). The study explored various thicknesses of the silver and tungsten trioxide layers within a MoO3/Ag/WO3 configuration to achieve the best performance, measured by Average Visual Transmittance (AVT).

The investigation revealed that the thickness of both the silver and tungsten trioxide layers significantly affects the structure’s transparency. By adjusting these thicknesses in the range of 0 to 20 nanometers, the team found a minimum AVT of 32.48%. Importantly, the analysis showed that this MoO3/Ag/WO3 structure can function as a practical transparent contact, even exceeding the 25% transparency threshold considered suitable for window applications.

While increasing the thickness of the tungsten trioxide layer had a limited impact on AVT, changes in the silver layer thickness showed a considerable effect. Specifically, when the silver layer exceeded 8 nanometers, AVT tended to drop below 80%. This indicates that the silver layer plays a more crucial role in determining the overall transparency of the contact.

The study also found that the highest AVT was achieved with a silver layer thickness of 4 nanometers and a tungsten trioxide layer thickness of 6 nanometers. Analysis of reflection spectra further indicated that tungsten trioxide acts as an anti-reflection layer, particularly beneficial when used with silver, which has a high refractive index.

Furthermore, the research assessed other optical parameters of the MoO3/Ag/WO3 structure, including Color Rendering Index (CRI), color coordinates, Correlated Color Temperature (CCT), and maximum transmittance. The lowest and highest AVTs recorded were 32.48% and 97.3%, respectively, depending on the layer thicknesses.

It was observed that increasing the tungsten trioxide layer thickness improved AVT, especially when the silver layer was thicker than 10 nanometers. This is attributed to the thicker dielectric layer mitigating the transparency reduction caused by electric fields and plasmonic effects associated with thicker metal layers.

For applications demanding accurate color reproduction, such as LED lighting and high-resolution displays, the study evaluated the Color Rendering Index (CRI). The MoO3/Ag/WO3 structure exhibited excellent color rendering properties, with CRI values above 94 across the tested thickness range and exceeding 98 for specific thicknesses. The structure with 6 nm silver and 16 nm tungsten trioxide achieved a maximum CRI of 98.6.

Interestingly, the structure optimized for maximum AVT did not coincide with the one for maximum CRI. While the highest AVT structure had a CRI of 95.75%, the structure with 6 nm silver and 16 nm tungsten trioxide offered a slightly lower AVT of 95.38% but a significantly higher CRI and neutral color coordinates. This 6 nm silver, 16 nm tungsten trioxide configuration also demonstrated a Color Temperature close to daylight and excellent performance in reproducing red color, a critical aspect for applications like lighting and displays.

The researchers noted that while ultra-thin silver layers are optimal in these structures, their practical implementation requires advanced deposition techniques to ensure smooth, continuous, and low-resistance films. However, with ongoing improvements in deposition methods, the MoO3/Ag/WO3 transparent contact structure holds significant promise for integration into next-generation optoelectronic devices, offering a balance of high transparency, excellent color rendering, and suitable electrical conductivity.

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Apple has announced new software features aimed at improving accessibility for individuals with mobility, vision, hearing, and cognitive disabilities. These upcoming technologies underscore Apple’s dedication to accessibility as a fundamental human right and builds upon their history of creating customizable products for all users.

Later this year, software updates across Apple’s operating systems will introduce several key features. People with limb differences will gain the ability to navigate Apple Watch using AssistiveTouch. iPad will gain compatibility with third-party eye-tracking hardware, enhancing control options. For individuals with blindness or low vision, the VoiceOver screen reader will be enhanced with on-device intelligence to identify objects within images. To support neurodiversity, new background sounds will be introduced to help reduce distractions. Furthermore, Made for iPhone (MFi) hearing aids will soon support bi-directional functionality for those who are deaf or hard of hearing.

Apple is also launching SignTime on Thursday, May 20th, a new service that allows customers to communicate with AppleCare and Retail Customer Care using American Sign Language (ASL) in the US, British Sign Language (BSL) in the UK, or French Sign Language (LSF) in France directly within web browsers. SignTime will also be available at Apple Store locations, offering on-demand remote access to sign language interpreters without prior appointments. Initially launching in the US, UK, and France, Apple plans to expand SignTime to more countries in the future.

Sarah Herrlinger, Apple’s senior director of Global Accessibility Policy and Initiatives, stated that Apple believes technology should be responsive to everyone’s needs and emphasized the company’s commitment to integrating accessibility into all their products. She added that these new features represent advancements in next-generation technologies, making Apple technology more accessible and enjoyable for a wider range of users.

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