Stockholm  - Charles K Kao, Willard S Boyle and George E Smith - dubbed "the masters of light" - on Tuesday won the 2009 Nobel Prize in Physics for discoveries behind data and telephone transmissions and the digital camera.

Kao was cited "for groundbreaking achievements concerning the transmission of light in fibres for optical communication," while Boyle and Smith were cited for inventing the CCD sensor, the Royal Swedish Academy of Sciences said.

Kao, who was born in Shanghai in 1933 and holds British and US citizenship, was awarded half the prize worth 10 million kronor (1.4 million dollars).

Boyle - who has US and Canadian citizenship - and Smith, an American, shared the other half of the prize for their invention. The CCD is likened to a "digital camera's electronic eye."

"We are the ones that I guess started this profusion of little small cameras working all over the world," Boyle told reporters at the academy's headquarters in Stockholm over a loudspeaker phone from Canada where he was born in 1924.

"The most important part of our invention that affected me personally was when the Mars probe was on the surface of Mars and used a camera like ours, and it would not have been possible without our invention," Boyle added. "We saw for the first time the surface of Mars. ... It was very exciting."

It has also been of importance for astronomy and "without CCD we would not have seen the astonishing images of space taken by the Hubble space telescope," the academy said in a statement.

Kao's discovery was made in 1966, the year after he was awarded a PhD in electrical engineering from Imperial College, London.

He calculated how to transmit light over long distances via optical glass fibres.

These fibres are key for today's communications and "text, music, images and video can be transferred around the globe in a split second," the academy said.

Kao retired in 1996, having been vice-chancellor at the Chinese University of Hong Kong.

Boyle has a PhD in physics from McGill University in Canada. He retired in 1979.

Smith, who was born in 1930, has a PhD in physics from the University of Chicago. He is a former head of VLSI Device Department, Bell Laboratories in New Jersey, US. He retired in 1986.

The physics prize was the second of this year's Nobel prizes to be announced.

US researchers Elizabeth Blackburn, Carol Greider and Jack Szostak won the 2009 Nobel Prize in Medicine for discoveries that are significant to knowledge about cancer, ageing and inherited genetic diseases.

The award ceremony is scheduled for December 10, the anniversary of the death of Alfred Nobel, the inventor of dynamite who endowed the awards.

The Nobel for chemistry is to be announced Wednesday, followed by prizes for literature, peace and economics in the days that follow.  dpa