New polariser for more efficient LCD displays

Research led by an Indian-origin engineer has led to a polarising filter that allows in more light, leading the way for mobile device displays that last much longer on a single battery charge and cameras that can shoot in dim light.

Polarisers are indispensable in digital photography and LCD displays, but they block enormous amounts of light, wasting energy and making it more difficult to photograph in low light.

The researchers created the filter by etching a silicon wafer with microscopic pillars and holes.

This new concept in light filtering can perform the same function as a standard polariser but allows up to nearly 30 percent more light to pass through, said Rajesh Menon, electrical and computer engineering associate professor at University of Utah.

Sunlight as well as most ambient light emits half of its energy as light polarized along a horizontal axis and the other half along a vertical axis.

A polariser typically allows only half of the light to pass because it is permitting either the horizontal or vertical energy to go through, but not both.

Meanwhile, the other half is reflected back or absorbed, but the resulting image is much darker.

LCD displays on devices such as smartphones and tablets have two polarisers that ultimately throw away most of the light when working with the liquid crystal display.

"If one can increase that energy efficiency, that is a huge increase on the battery life of your display. Or you can make your display brighter," Menon said.

The study appeared in the journal Optica, a new journal from The Optical Society of America.