Date: 16/07/2012

Projector in your phone is re-designed for power-efficiency

The present smart-phones featuring pico projectors are not that worth to use them all the time (due to high power consumption) and in all the light conditions (poor visibility). To improve the performance of pico projectors, researchers from North Carolina State University and ImagineOptix Corporation have developed new technology to convert unpolarized light into polarized light, which makes projectors that use liquid crystal (LC) technology to make the projectors more efficient .

Since the pico-projectors use LEDs which produce unpolarized light, so this has to be converted into polarized light before it can be used. The process of passing the unpolarized light through a polarizing filter generated heat and some percentage of light is also is lost, but the new technology developed at NC State allows approximately 90 percent of the unpolarized light to be polarized and, therefore, used by the projector.

pico projector

Researchers used the technology to create a small picoprojector, shown in the above picture which could be embedded in a smartphone, tablet or other device. (Image courtesy of ImagineOptix Corp.)

“This technology, which we call a polarization grating-polarization conversion system (PGPCS), will significantly improve the energy efficiency of LC projectors,” says Dr. Michael Escuti, co-author of a paper describing the research and an associate professor of electrical and computer engineering at NC State. “The commercial implications are broad reaching. Projectors that rely on batteries will be able to run for almost twice as long. And LC projectors of all kinds can be made twice as bright but use the same amount of power that they do now. However, we can’t promise that this will make classes and meetings twice as exciting.”

The NCSU release explains: The technology is a small single-unit assembly composed of four immobile parts. A beam of unpolarized light first passes through an array of lenses, which focus the light into a grid of spots. The light then passes through a polarization grating, which consists of a thin layer of liquid crystal material on a glass plate. The polarization grating separates the spots of light into pairs, which have opposite polarizations. The light then passes through a louvered wave plate, which is a collection of clear, patterned plates that gives the beams of light the same polarization. Finally, a second array of lenses focuses the spots of light back into a single, uniform beam of light.

The paper, “Efficient and monolithic polarization conversion system based on a polarization grating,” was published July 10 in Applied Optics. The paper was co-authored by Drs. Jihwan Kim and Ravi Komanduri, postdoctoral researchers at NC State; Kristopher Lawler, a research associate at NC State; Jason Kekas, of ImagineOptix Corp.; and Escuti. The research was funded by ImagineOptix, a start-up company co-founded by Escuti and Kekas.