The demand for ultra-high-resolution imaging has reached new heights. By leveraging advanced optical designs and wave optical effects, a precision glass-based waveguide technology is set to bring unprecedented resolution and color fidelity to remote imaging systems.
BY ANDREA RAVAGLI, SCHOTT NORTH AMERICA, AND HAIKE FRANK, SCHOTT
Various disciplines use high resolution imaging to enhance and ultimately improve the information that a user can obtain from a scene. At the component level, high resolution image guides, such as glass nano waveguides based on Transverse Anderson Localization (TAL), can further augment the effect that high resolution imaging offers.
Transverse Anderson Localization Optical Fiber (TALOF)-based nano waveguides for high resolution imaging. Courtesy of SCHOTT.
The benefits apply to numerous applications. In minimally invasive health procedures, for example, endoscopes and other surgical tools capture sharper, clearer images of internal structures. This improves the prospects for clinicians to detect early-stage diseases, such as cancers, for which speed and accuracy are vital to accurate diagnoses and the implementation of treatment options. High resolution imaging also plays an important role in industrial inspections, such as those that are necessary in oil and gas plants. Nano waveguides additionally deliver advantages in extreme environments and hard-to-reach areas, enhancing precision in these applications as well as in quality control processes.
For systems that require reliable imaging without external power sources, such as passive viewing systems and/or optical surveillance devices for emergency egress, waveguides based on TAL offer a durable and power-independent solution. This makes them invaluable for long-term installations in remote and/or rugged environments: For example, night vision systems used in the defense industry benefit significantly from the superior figure-of-merit values provided by TAL waveguides. Similarly, in high-stakes defense operations, where visibility is limited, an enhanced resolution and broader field-of-view can mean the difference between success and failure.
From wave interference to improved imaging
As its name implies, TAL technology applies the principle of Anderson Localization, a wave optical phenomenon that restricts wave diffusion in disordered systems. Nobel laureate Philip Anderson introduced the concept of Anderson Localization in 1958, originally to describe the absence of wave diffusion in disordered systems.
Transverse Anderson Localization Optical Fibers (TALOF), in both rigid and flexible formats. Courtesy of SCHOTT.
Though the initial focus was on electron conduction, researchers later recognized the broader implications for Anderson Localization, and TAL extends this principle into optical waveguides such as optical fibers (OF), also referred to as TALOF, by creating highly disordered yet controlled waveguide structures.
Today, TAL-based nano imaging essentially functions to guide light anywhere across its transverse path. In the context of glass optical fibers, this is achieved by constructing rigid or flexible nano waveguides from at least two different types of optical glass arranged in a disordered configuration (glass types used in this case span borosilicate glass, fused silica, and/or infrared glasses). This disordered configuration suppresses light scattering and ensures precise localization within nanoscale dimensions.
By reducing the diameter of the structural elements to below 1 µm, nano waveguides, or TALOF, use light diffraction to achieve resolutions that far exceed 200 line pairs per millimeter (lp/mm), even with white Lambertian illumination. This surpasses state-of-the-art fiber optic systems, which rely on total internal reflection — which itself limits the maximum achievable resolution to the size of the fiber. In addition, signal crosstalk between fibers degrades performance, adding noise to the transported images.
The result is that the best performance obtained in optical fiber bundles for light localization is typically 4 µm. By contrast, TALOF achieves narrow localization spots as small as 1.5 µm. This enables the guidance of images that are sharper, more accurate, and better suited for high-performance applications.
Glass quality: A critical measurable
Of course, the performance of TAL-based nano waveguides can be traced to the optical materials used during fabrication. Using advanced optical glass rather than polymer materials, for example, is a distinction that offers several advantages.
First, optical glass provides unparalleled mechanical, thermal, and chemical stability, ensuring consistent performance even in extreme settings, such as harsh environments, very high temperatures, and/or corrosive conditions (each of which is encountered in industrial and defense applications). Additionally, the optical properties of glass, including higher refractive index consistency and reduced material dispersion, result in sharper, more accurate image transmission with minimal distortion.
Comparison of the functional principles of Transverse Anderson Localization Optical Fiber (TALOF)-based nano imaging (top) and traditional fiber optics. TALOF guides light anywhere across its transverse path, whereas traditional fiber optics rely on total internal reflection to transport light. Courtesy of SCHOTT.
Polymer-based solutions are more prone to degradation over time, especially under UV exposure. These polymer-based nano waveguides are additionally apt to produce lower resolution images due to their inherent limitations in material uniformity and optical precision. These qualities make glass the superior choice for demanding applications that require both reliability and optical excellence.
Fundamental benefits
Conventional fiber optics is well suited for general-purpose imaging applications. However, its reliance on total internal reflection limits resolution to the size of the fibers themselves. By localizing light at sub-micron levels, TALOF achieves clarity and accuracy that these conventional systems cannot.
Still, traditional fiber optics should not be dismissed; TALOF can complement its use, filling gaps in resolution-sensitive and high-performance imaging scenarios. In other words, both as a standalone solution and in combination with other technologies, TAL-based nano waveguides offer transformative advantages over conventional imaging approaches.
In assessing the value that nano waveguides bring to imaging applications, improved resolution is a vital measurable. Nano waveguides achieve resolutions that far surpass the limits of traditional fiber optics. This is critical in applications such as medical diagnostics, where high-resolution imaging ensures that fine details, such as tissue microstructures or vascular anomalies, are clearly visible. This enhanced resolution can reduce diagnostic errors and support earlier, more effective interventions.
Resolution comparison of nano imaging (top) and traditional 4-µm fiber optics show real-life examples of imaging performance. Courtesy of SCHOTT’s Global Technology Center.
The precision-engineered combination of the optical materials in TALOF also provides exceptional image contrast and color fidelity. High contrast is essential for distinguishing subtle differences in texture, density, and/or color in imaging environments, such as identifying small defects during industrial inspections or detecting minuscule abnormalities during surgery. Color fidelity ensures accurate reproduction of hues. This applies directly to fields such as ophthalmology and dermatology, where even slight color deviations can alter diagnoses.
Another benefit involves light confinement within an area smaller than the typical camera pixel size — a feature enabled by TAL-based waveguides. This simplifies detector alignment and bonding processes to enable faster manufacturing times and reduced production costs. It also benefits industries where scalability and rapid prototyping are essential, such as custom medical device production or defense equipment manufacturing.
New possibilities for TALOF applications
The potential of TALOF extends beyond its current applications, opening avenues for innovation in emerging fields. These include quantum imaging, where precise light localization could be hanressed to enable advanced imaging modalities that operate at the quantum level. TAL-based waveguides could also find use in space exploration: The resilience and resolution of these components make them ideal for imaging in harsh environments and extreme conditions such as planetary surface analysis or satellite-based inspections.
Further, in the development of augmented reality and virtual reality (AR/VR) devices, the high-resolution waveguides could enhance visual clarity, enabling more immersive experiences in training, gaming, and simulation. And in biophotonics, TALOF technology could enable breakthroughs in studying cellular and molecular structures, particularly in live samples.
Still, the practical application of TALOF in imaging systems is a relatively recent innovation: From its roots in quantum mechanics to its current (and expanding) role in next-generation imaging, TAL-based nano waveguide technology is revolutionizing the capture and transfer of visual information. With unparalleled resolution, color fidelity, and versatility, TALOF is not just pushing the boundaries of what is possible in imaging — it is creating entirely new opportunities across critical industries.
Meet the authors
Andrea Ravagli is development scientist at SCHOTT North America’s Lighting and Imaging Technology Center, in Southbridge, Mass.; email: [email protected].
Haike Frank is director, marketing and business development manager at SCHOTT Lighting and Imaging in Mainz, Germany; email: [email protected].