Researchers have developed a full-color near-eye display that uses three stacked holographic gratings, each engineered to direct red, green or blue light. The new design could help advance compact, energy-efficient augmented reality (AR) glasses for use in a variety of professional and consumer applications.
Holographic gratings are microscopic optical structures that use a laser-recorded interference pattern to precisely redirect and shape light. In a near-eye display, they can be used to couple light into and out of a transparent waveguide, allowing digital images to be delivered to the viewer’s eye.
“As augmented reality becomes increasingly integrated into everyday life, there is a growing need for lightweight, energy-efficient and easy-to-manufacture display technologies,” said research team leader Raj Kumar from CSIR- Central Scientific Instruments Organisation and the Academy of Scientific and Innovative Research (AcSIR), both in India. “Our stacked grating design can produce bright images while using less power, which is especially beneficial for enabling lightweight, battery-powered AR glasses that display clear virtual images in bright indoor and outdoor environments.”
In the Optica Publishing Group journal Applied Optics, the researchers report on a lab prototype that incorporates the stacked holographic gratings. The new design is enabled by a prism-free fabrication method that eliminates the need to align multiple gratings, making multilayer holographic light couplers easier to manufacture and reproduce.
“This technology could be useful in see-through displays used in AR glasses for navigation, industrial assistance, education, medical visualization, maintenance, training and other applications where color information must be overlaid on the real world,” said the paper’s first author Sheenam Saxena from CSIR. “It should also be possible to extend the technique to the fabrication of large-sized displays, such as head-up displays (HUDs) for vehicles.”
