Industrial-grade anti-reflection coatings with extreme scratch resistance

Abstract

Anti-reflection coatings are widely used throughout the field of optical technology such as in corrective eyeglasses, camera lenses, and microscope optics, to improve the transmittance and reduce the reflectance of glass and other transparent materials. To date, these coatings have suffered from relatively poor scratch resistance and high scratch visibility compared to standard glasses. This has limited their use in applications requiring high mechanical durability such as on the chemically strengthened glasses widely used in modern touch screen devices. Here extremely scratch-resistant anti-reflection coatings are fabricated using industrially scalable reactive sputtering processes. These coatings provide a combination of surface reflectance below 0.7%, low color shifts, nanoindentation hardness as high as 18 GPa, and levels of scratch resistance which dramatically exceed commercial chemically strengthened glasses. An interdisciplinary opto-mechanical design approach has enabled a significant paradigm shift in the use of high-precision optical coatings for mechanically demanding applications. As a direct outcome of the work reported in this Letter, similar coating designs have been successfully deployed on millions of consumer electronics devices with very robust field performance.