Dr William Bennett

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Physicist and pioneer in gas lasers

Born: 30 January, 1930, in Jersey City.

Died: 29 June, 2008, in Haverford, Philadelphia , aged 78.

WILLIAM Bennett jnr was a physicist and inventor who helped develop a gas laser in the 1960s, using technology that later revolutionised surgery and made possible compact-disc players and supermarket check-out scanners.

In the late 1950s, while working at Bell Laboratories in Murray Hill, New Jersey, Bennett and a small scientific team assembled a gas laser, the first of its kind able to send out a continuous beam of red light.

The team, which included Donald R Herriott and Ali Javan, trapped helium and neon in a pressurised tube and agitated the gases' atoms with an electrical current. Internal mirrors at each end of the tube redirected the resulting particles of light to send them out in a concentrated and continuous beam.

The helium-neon gas laser described by Bennett and the team in the journal Physical Review Letters, in 1961, represented a departure from an earlier laser, which derived its beam from a solid material, synthetic ruby.

Gas lasers have some advantages over those using ruby and other solid materials. For example, although both types are in wide use, gas lasers allow heat to disperse from the laser's tube relatively rapidly. Dr Javan and Bennett received a patent for the gas laser in 1964.

In following years, Bennett and others experimented with argon, krypton, xenon and similar gases and studied the qualities and burning power of their laser beams. Gas lasers have been used in construction and surveying and to cut or weld materials for industrial applications.

Lasers have also profoundly altered eye surgery and are now commonly used to modify precisely the shape of the cornea and sharpen vision and to halt the progress of macular degeneration and other ocular diseases.

Bennett left Bell Laboratories and in 1962 joined the newly formed department of physics and applied science at Yale University. There, he continued his laser research, studied musical sound, and looked into possible health effects of power lines and electromagnetic fields, a risk he believed to be significantly overrated.

William Ralph Bennett junior was born in 1930, in Jersey City, New Jersey. He graduated from Princeton University, then received a doctorate in physics from Columbia in 1957.

In 1964, he was named a professor of physics and applied science at Yale, and remained there for the rest of his career. Bennett became a professor emeritus of engineering, applied science and physics in 1998. From 1981 to 1987, he was master of Silliman College at Yale.

Among his publications, Bennett wrote a book, The Physics of Gas Lasers (1977). He also wrote a textbook, Introduction to Computer Applications for Non-Science Students (1976), that was an early resource in its field.

In the 1970s, Bennett introduced a popular undergraduate course for humanities and social-science students at Yale, intended to show the problem-solving promise of nascent computers.

A colleague, Werner Wolf, a professor emeritus of engineering and applied science at Yale, said the course proved to be both prescient and persuasive, and "made the whole concept of computers exciting".

Part of the course, Dr Wolf said, was dedicated to practical challenges; Bennett told his students to calculate the ballistics of catapulting frozen loaves of bread across the New Haven campus.

William Bennett is survived by his wife, the former Frances Commins. The couple were longtime residents of New Haven, and moved to Haverford in 2000. He is also survived by a son, two daughters, a sister and five grandchildren.