Periodic Reporting for period 1 - GLASS (Green Laser-Assisted Surface Structuring)
Berichtszeitraum: 2023-05-01 bis 2024-04-30
Modern industry is teeming with devices that encompass the generation, manipulation, and absorption of light. Electronic devices in particular incorporate glass pieces that cover internal parts of those devices while letting light unobstructed pass through them. However, all transparent materials reflect part of the incident light that is trying to propagate through them. This effect creates glare and reduces the clarity and quality of the transmitted image. It can further impair visibility, leading to eye strain and discomfort in devices like eyeglasses, computer screens, and smartphones. In more technical applications, such as optical instruments, cameras, and microscopes, reflections can distort measurements and degrade the accuracy of observations while also diminishing the efficiency of advanced technological and industrial systems. Therefore. the industry has employed several technologies to suppress this damaging phenomenon. The most widely used technologies involve the use Anti-reflective (AR) coatings and etching processes. AR coatings consist of single or multi thin-layered materials that are deposited on top of the surface of glass in a way that can inhibit surface reflection by controlling the composition and thickness of the constituent layers of the coating. On the contrary, etching techniques modify the topography of the glass surface at the micro to nano scale, by using reactive chemical agents or plasma. The surface reflection is hereby suppressed owing to the modified surface topography of the glass. Both these technologies involve multiple step fabrication processes, are time consuming and use consumables and often harsh chemicals. Additionally, coatings can be exfoliated relatively easily with temperature gradients or radiation, while etched surfaces are easily abraded. In the context of “Green Laser-Assisted Surface Structuring” (GLASS) project, we aim to develop Biomimetic’s unique glass laser nanotexturing technology and adapt it to fit the market of displays and specialized optics. GLASS technology is a simple, single step process that modifies the surface of glass through the use of lasers. This modification occurs due to material melting and self-organization phenomena that are initiated by the laser. Through meticulous adjustment of the laser parameters, we can take advantage of those self-assembly mechanisms and give rise to functional nanotextures. The appropriate laser parameters are dependent on the individual glass substrate, it’s composition and physical properties. The modified glass surfaces exhibit pronounced AR optical characteristics which is attributed to the geometrical features of the attained surface morphology. This morphology is composed of a 2D periodic array of nanometric sized pillars that resembles the pattern that is found naturally on the wings of certain species of butterflies and cicadas. In the framework of the project, we aim to extend the applicability of this process to glass compositions such as aluminosilicates that are highly relevant on the industry of displays. Moreover, we plan to enhance the abrasion resistance of the nanotexture to bring it to electronic display standards, which is the main bottleneck of the technology to reach market readiness. Finally, we plan to manufacture an automated laser texturing machine, that will be able to process glass with a push of a button. This laser machine will be controlled with a proprietary software and will be able to nanotexture glass with the AR inducing structures.
In the beginning, a set of industry relevant glasses were proposed by consortium partner Corning. Those glasses were experimented upon at Biomimetic and the laser nanotexturing process was modified appropriately to be able to generate an AR inducing nanopattern. More specifically, an initial feasibility study was conducted which was able to identify a proper laser parameter window that can initiate the formation of an AR nanotexture on the proposed glasses. Following this initial study, a more complete study optimized the nanotexturing laser parameters and achieved an AR performance measured as XXX % Reflectance and XXX % Transmittance in the visible spectrum. Furthermore, the mechanical robustness was assessed. Several test samples with sizes similar to small sized screens, were fabricated and sent for characterization to Corning. At the same time, another pattern was developed that is more mechanically robust and samples featuring this texture were sent to Corning for characterization. At the same time, with consortium partner LASEA, we are building an AI module for the final laser machine, that will be able to optically investigate in-line the nanotextured materials and give predictions regarding the laser parameters. To train the AI, several samples featuring a great number of test areas were created and sent to LASEA. So far, we have demonstrated the applicability of the technology on display glasses at sizes equivalent to small screens of 100 mm X 100 mm and have set the framework for the construction of the automated laser machine. A patent has been filed that protects the intellectual property of the laser process.
We continue to further develop the technology with more research and modifications to the texturing process that can lead to enhancement of the optical performance of the textured glasses. Furthermore, we explore the possibility to control the periodicity of the attained nanotexture and the effect of this on the optical properties of the glass which is highly needed in the market of optics. Moreover, we are working to develop a hybrid texture that comprises the traditional AR texture with the newly discovered abrasion resistance texture as a means to attain an AR effect that also demonstrates enhanced abrasion resistance. Finally, we undertake demonstration activities for applications that go beyond specialized optics and display markets to extend the applicability of the process and support access to new markets.