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Matt Hall. Portrait of a man wearing glasses and a blue checkered shirt, smiling against a dark blue background with a hexagonal pattern. The Electro Optics logo appears in the top right corner.©️ Matt Hall, Global Product Director, G&H | Artemis

Anti-reflective Coatings that Push Optical Performance to the Limit are “Anything but Routine”

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An article by James Wormald, Electro Optics

G&H | Artemis’ Global Product Director Matt Hall reveals how advanced anti-reflective coatings boost defence, medical and industrial optics, from visible to LWIR.

Electro Optics: Tell me about your development of anti-reflective optical coatings.

Matt Hall: Anti-reflective (AR) coatings are sometimes perceived as simple or routine, but in practice they are anything but. What can appear to be a straightforward AR layer is, in reality, a carefully engineered solution, particularly when wide spectral coverage, high durability and precise control of factors such as polarisation and angular performance are required.

At G&H | Artemis, we have a design catalogue containing more than 300 unique AR coatings. Each has been tailored to meet specific requirements, covering spectral regions from visible through NIR, MWIR and LWIR, while also addressing other critical parameters.

In the LWIR range, for example, we frequently use diamond-like carbon (DLC) to meet environmental and mechanical durability demands, especially in harsh or abrasive environments. For laser applications, designs often need to achieve a high laser-induced damage threshold (LIDT), which calls for meticulous material selection and precise control of the deposition process. For wide-angle or polarisation-sensitive systems, we have developed coatings that maintain low reflectance and preserve polarisation across a broad range of incidence angles.

A close-up image shows a person wearing purple gloves carefully applying a dark adhesive or resin onto a clear glass square using a small wooden stick. The glass is held delicately in one hand, while the other hand guides the application. The environment suggests a laboratory or precision manufacturing setting.

EO: And how does the technology work, exactly?

MH: Technically, the principle is to minimise surface reflectance by exploiting destructive interference in carefully designed multilayer dielectric stacks, with optical thickness and refractive index contrast tuned for the application. However, this is just the starting point. In reality, each design must be matched to its substrate; the chosen deposition method; the mechanical durability needs and the intended operating environment, all of which can influence performance.

AR coatings may not always attract attention, but they remain essential to optical performance, and developing them continues to be one of the most rewarding technical challenges.

EO: So what applications do they tend to be used for?

MH: AR coatings are fundamental to almost every optical system. Without them, reflection losses at each surface reduce throughput, degrade image quality and can significantly impair overall system performance. But they’re especially important in multi-element assemblies, where even minor inefficiencies accumulate rapidly.

They are indispensable in sectors where performance, efficiency and reliability are paramount, such as defence and aerospace, where systems must operate in extreme environments; medical imaging, where clarity is critical; and industrial sensing and metrology, where accurate optical signals are essential.

In laser-based systems, the demands are even greater. Coatings must minimise absorption to prevent laser-induced damage and maintain signal quality, while scatter must be kept to a minimum to avoid beam degradation. Whether for visible, infrared or broadband applications, AR coatings remain key to achieving high optical performance in increasingly demanding conditions.

A woman wearing a white lab coat and purple gloves is closely inspecting a rectangular piece of blue-tinted glass or optical material under a bright light source. She is seated at a workstation with a textured metal surface and a yellow cleaning cloth nearby, suggesting a cleanroom or laboratory environment.©️ Private

EO: What’s at the core of your approach? And how do your solutions outperform those of others?

MH: Our approach recognises that a successful anti-reflective coating must not only meet its optical specification in theory but also be manufacturable, durable and reliable in service. Two elements underpin every coating we design, the optical concept and its practical realisation in production.

Modern software can generate impressive theoretical designs, but many of these prove too sensitive to manufacturing tolerances, rely on impractical materials or cannot be reproduced consistently in real-world vacuum systems. This is where our experience makes the difference.

Drawing on more than six decades of in-house knowledge, we bridge the gap between simulated performance and production reality. We integrate design expertise with a detailed understanding of material behaviour, coating process capabilities and environmental demands. This ensures our designs are not only spectrally optimised, but also robust, repeatable and tolerant of real manufacturing conditions.

Compared with our own, earlier generations even, our coatings are more stable, offer better environmental resilience and are tailored more closely to each application. Whether meeting high LIDT requirements, preserving polarisation at oblique incidence or delivering multi-band performance from visible through to LWIR, our solutions are designed for consistent, large-scale production without compromising performance.

Two technicians in full cleanroom suits, including gloves, face masks, and protective eyewear, are working in a sterile laboratory environment. One is seated, inspecting a tray of small components, while the other stands in the background examining an object under a light. The setting is brightly lit and meticulously clean, indicating high-precision or contamination-sensitive work.

EO: Do you have any especially exciting ongoing projects you can tell us about?

MH: A recent project we are particularly proud of involved the development of a rugged, low-reflection broadband AR coating for polymer optics. Plastics present unique challenges, particularly with adhesion, due to their organic nature. To address this, we undertook a detailed study of the substrate film interface to identify the most effective adhesion-promoting layer without compromising other properties.

Once the adhesion layer was established, the rest of the coating stack was optimised to deliver both the required spectral performance and exceptional environmental stability. We also ensured the design met strict mechanical durability standards, enabling it to perform consistently in challenging operational environments while maintaining very low reflectance.

EO: That sounds difficult. What were some other challenges you encountered along the way, and how did you overcome them?

MH: Controlling the process environment was essential. Temperature had to be kept within tight limits during deposition to prevent damage to the polymer substrate and maintain adhesion. Ion bombardment was carefully managed to achieve film densification without inducing excessive stress, which could compromise stability.

Each layer’s thickness was measured and adjusted with high precision to eliminate cumulative errors, ensuring the final coating matched the design performance exactly. Through these controls, we managed to overcome the inherent difficulties of producing high-performance AR coatings on polymer substrates.

A man in a lab coat and glasses closely examines an optical component using a microscope. Above the microscope is a mounted, curved optical filter with a green-blue hue. The room is dimly lit, with focused lighting highlighting the equipment and the man's concentrated expression.

EO: Tell me about some of the tangible improvements that have been made to products, that wouldn’t have been possible without anti-reflective coatings.

MH: AR coatings have significantly improved performance in both private and public sector applications. One of the most notable growth areas has been polymer optics for head-mounted displays, particularly in augmented reality systems.

The low weight and cost of plastics make them ideal for wearable devices, where comfort and size are critical. However, these optics rely heavily on durable, high-performance thin films to deliver the optical clarity and efficiency required. Advances in coating design and deposition techniques have enabled polymer-based optics to combine excellent spectral performance with the durability needed to withstand demanding operational and environmental conditions. This has accelerated their adoption in advanced defence, industrial and consumer technologies.

EO: How do you integrate experimental research with production processes to ensure innovations are translated into products as quickly, as efficiently and as economically as possible?

MH: At G&H | Artemis, we have a long tradition of working with academic partners and research institutes on R&D programmes. Typically, this begins with in depth design and feasibility studies, informed by our forty-seven years of experience, to create a robust development plan before practical work begins.

We assemble a multidisciplinary team of design and manufacturing engineers responsible for delivering that plan. The process incorporates multiple review and verification stages to track progress, manage risks and ensure the outcome meets both performance and cost targets. This structured, yet agile, approach allows us to move innovations from concept to production efficiently, without compromising quality or manufacturability.

Colleagues inspecting optical coatings - Two women wearing white lab coats are working in a dimly lit lab. The woman in the foreground is holding up a blue-tinted optical component, inspecting it carefully under a focused light. The background features another woman seated and working at a computer station. The scene emphasizes precision work in a controlled laboratory environment.

EO: And in the future… what will be the next big leap in terms of technical capability, brought about by anti-reflective coatings?

MH: Anti-reflection films have been central to optical performance since the early days of the industry, and they remain the most widely used and versatile coating type. As new substrate materials emerge, such as germanium chalcogenide alternatives for infrared applications, the coating designs, materials and processes must be revisited and optimised to maintain spectral performance and durability.

Looking forward, the most significant advances will come from the combination of new materials, innovative deposition methods and application-specific designs. The continued rise of polymer optics in wearable, medical and space systems will require AR coatings that are not only spectrally optimised but also flexible, exceptionally durable and compatible with high-volume manufacturing.

We also expect to see more multi-functional coatings, where anti-reflection performance is combined with other properties such as scratch resistance, hydrophobicity or high laser damage resistance. Such developments will expand the capabilities of both commercial and defence optical systems, enabling them to operate reliably in increasingly challenging environments.

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