donderdag 26 juli 2012

Projectors to double brightness with polarisation breakthrough.

Liquid crystal (LC) based projectors could become almost twice as energy efficient and much cheaper as researchers from North Carolina State University in the USA and ImagineOptix Corporation reveal a revolutionary polarising technology. The breakthrough means projectors that rely on batteries will be able to run for almost twice as long and all LC projectors can be made twice as bright.

All LC projectors utilise polarised light. However, researchers say that efficient light sources, such as LEDs, produce unpolarised light. As a result, the light generated by LEDs has to be converted into polarised light before it can be used.

According to NC State researchers, the most common method of polarising light involves passing the unpolarised light through a polarizing filter. They claim that this process wastes more than 50% of the originally generated light, with the bulk of the "lost" light being turned into heat. This is a major reason that projectors get hot and have noisy cooling fans.

The new technology, demonstrated in a small pico projector and developed at NC State, allows approximately 90 percent of the unpolarised light to be polarised and, therefore, used by the projector

"This technology, which we call a polarisation grating-polarisation conversion system (PGPCS), will significantly improve the energy efficiency of LC projectors," said Dr. Michael Escuti, co-author of a paper describing the research and an associate professor of electrical and computer engineering at NC State.

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.

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