Timothy J. Nevitt

Efficient LED light distribution cavities using low loss, angle-selective interference transflectors

Recent advances in solid state light source efficiency and luminance present the technical challenge of distributing light from very small point sources to large areas, with area distribution ratios having orders of magnitude greater than previously addressed. Broad adoption of LEDs in lighting and liquid crystal displays is in part contingent on addressing this fundamental light distribution issue. Here we present new materials based on giant birefringent nanotechnology which address these deficiencies allowing us to guide light in air via a novel light distribution system. Resulting from controlled in-plane and out-of-plane x,y,z refractive indices of adjacent layers, these multilayer interference films possess both angle selective and polarization selective reflectance. The angle selectivity can be tuned in both azimuth and polar angle, relieving a key constraint of prior materials. Our work has been done on a physically large scale enabling demonstration of large light management systems of industrial and practical relevance.

Efficient 3M PBS enhancing miniature projection optics

Over the past decade, 3M has developed a number of mobile projectors, with a goal towards providing the world’s smallest, most efficient projection systems. Compact size and efficiency are required characteristics for projection systems used in mobile devices and more lately, in augmented reality systems. In this paper we summarize the main generations of 3M light engine optical designs. We present the optical architectures of four light engines, including the rationale behind the illumination designs and the projection systems. In particular, we describe various configurations relating to the 3M polarizing beam splitter (PBS) which is key to enhanced efficiency of the miniature projection systems.

Giant birefringent optics in multilayer polymer filters

GBO design techniques can be used to control or eliminate the Brewster angle in multilayer interference stacks. Because certain GBO designs do not have the p-polarized losses near the Brewster angle, GBO filters have significant advantages in maintaining reflectivity when used in applications that require high reflectivity over a variety of angles.