Mar 25, 2021 Material

Inkron XR Materials

INKRON

Inkron, a Nagase Group Company, develops and manufactures advanced siloxane-based formulations and resin systems for AR/XR devices, 3D sensors and other diffractive optics related applications. Inkron’s core technology is centered around siloxane resins designed and synthesized in-house with advanced formulation knowhow. These optically clear resins are thermally and optically stable providing a perfect platform for the targeted applications. Advanced formulation steps facilitate meeting the various application-specific needs such high refractive index and nano-imprintability. Inkron provides other product families supporting the whole AR/XR process such as high RI black light absorbing materials, adhesives and encapsulation materials. Inkron has its primary manufacturing and R&D location in Finland. The optoelectronics and opto-packaging departments are in Taiwan. Inkron has worldwide representation.

Critical material solutions for AR/XR devices

The main application areas for inkron materials are found within the Optical Devices, Opto Packaging and Printed Electronics industries. The product range includes high and low Refractive Index (RI) coating materials for application in optical devices. These industry-leading optical coatings cover a record-breaking RI range between 1.1 and 2.0 for the VIS/NIR spectrum. The high RI materials are optimized for Nano Imprint Lithography (NIL). Target applications include DOE (Diffractive Optics Elements), like waveguides for AR/XR devices, optical diffusers, LIDAR and other photonic applications.
New high RI optical blackening materials are shown to drastically reduce the lens edge reflections and thus improve the optical performance of the light engine waveguide combination.
Other essential materials for the AR/XR field are Inkron’s low refractive index materials with an RI range of 1.1-1.4. Typical applications of the low RI materials are found in anti-reflective coatings (visible and NIR range), waveguide claddings, gap filling and adhesive layers.
Opto-packaging materials such as high-RI and UV-curable encapsulants as well as thermally conductive adhesives may find use in various areas such as eye tracking. High RI adhesives may be used in in certain display designs.
The product range includes also screen- and inkjet-printable stretchable conductive and dielectric inks including high RI inks.

Optical Coatings for XR Applications

Optical coatings play a crucial role in waveguide design and manufacturing. Optically clear high RI and NIL-processable resins are critical materials for Diffractive Optics Elements (DOE) used in AR/XR display units. The refractive index of the in and out coupling DOEs determines the Field of View of the AR glass. The higher the RI of the resin the bigger the FoV and thus the better the user experience.
Together with the substrate and the light engine, the processability and optical clarity of the resins determine the efficiency and picture quality of the waveguide. Therefore, the refractive index of the resin, the optical properties and processability of the formulation must be carefully balanced.

The complementing low RI coatings may be combined with the high RI resins in applications like anti-reflection coatings, cladding layers and gap filling of high Ri structures.

The RI range of optical coatings covers:

- Low refractive index (RI), optically clear, gap filling coatings. RI range from 1.1 to 1.4.
- High refractive index, NIL processable coatings. RI range from 1.55 to 1.9x.

An article with an in-depth description of Inkron's optical coatings for XR/AR applications was recently publsihed in PhtonicsViews magazine and can be read here: https://inkron.com/wp-content/uploads/2021/02/phvs01_Inkron_Perento.pdf

Inkron High Refractive Index Optical Black for XR Optical Elements

The IOB product family combines a high refractive index (RI) with high Optical Density (OD) thus eliminating edge reflections.
In AR-devices part of the light may reach the air/substrate interface at the edge of the substrate. The refractive index difference between the air and the substrate can be significant, typically 0.5 to 1.0 depending on substrate properties. As a result, part of the light is reflected back into the substrate causing significant contrast losses and other optical disturbances for the optics such as a lowered contrast of head-mounted displays. Traditionally the above phenomenon is countered by blackening the lens edges with a material with high Optical Density (OD). Thus, the light from the substrate enters the absorbing black layer where it is absorbed minimizing the reflections. The critical issue left unsolved by this approach, is the light that is reflected because of the refractive index difference between the substrate and the black matrix material.

Inkron now offers a patent-pending high refractive index black light absorbing material with substrate-matching refractive index and high Optical Density (OD). This combination effectively removes the reflections resulting from the refractive index mismatch. The clear advantage for device-integrators is the minimized back-reflection of light, decisively improving the contrast and optical performance of the device at hand.

Experiments with high refractive index glass (n=1.9) and Inkron optical light absorbing BLACK (n=1.9) show a 96% reduction of light reflection at visible wavelengths when compared to conventional light absorbing black (n=1.55).

The IOB products are available with an RI of 1.7, 1.8 and 1.9.

Material Options for the AR Device assembly

Inkron’s other materials may potentially be used in specific areas of the AR/XR device assembly process.

Inkron’s portfolio includes thermally conductive adhesives, structural adhesives and underfills, high RI and optically clear adhesives as well as high RI encapsulants and UV-cureable encapsulant materials. These products may for instance be used with eye tracking components as well as other sensors needed in environmental tracking.

The product package is complemented with a portfolio of printable inks. These inks are electrically conductive, non-conductive dielectric inks as well as optically clear inks with higher refractive index.

OEM Services

Inkron provides application support and services for its customers.

- Nano-imprint lithography: the available EVG 7200 tool is capable of handling wafer sizes up to 200 mm. This NIL tool is located in the clean room. Services include the testing and optimization of diffractive optical designs and the imprinting process, as well as preproduction and pilot runs.

Other potential services include:
- Opto-packaging services: pilot production and design of LED optics.
- Printing service: Printing and testing service of screen-printed structures and devices.
- R&D services: design, development, synthesis and characterization of new materials according to customer requirements.

INKRON

Inkron, a Nagase Group Company, develops and manufactures advanced siloxane-based formulations and resin systems for AR/XR devices, 3D sensors and other diffractive optics related applications. Inkron’s core technology is centered around siloxane resins designed and synthesized in-house with advanced formulation knowhow. These optically clear resins are thermally and optically stable providing a perfect platform for the targeted applications. Advanced formulation steps facilitate meeting the various application-specific needs such high refractive index and nano-imprintability. Inkron provides other product families supporting the whole AR/XR process such as high RI black light absorbing materials, adhesives and encapsulation materials.

Inkron has its primary manufacturing and R&D location in Finland. The optoelectronics and opto-packaging departments are in Taiwan. Inkron has worldwide representation.

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