When the Smithsonian Institution in Washington DC wanted to beef up the network connections between its various buildings, it found that fibre optic links were just too expensive.

Despite an unfortunate experience with one laser system, the institution persisted. A laser transmitter/receiver (transceiver) on the roof of one building now points to a second transceiver behind a window in the organisation's administrative headquarters.

Systems developed by Lightpointe, based in San Diego, California, carry data around the Smithsonian at speeds up to 155 megabits (million bits) per second (Mbps), around 100 times the speed of the conventional system that was in place before the institution installed its optical links.

The Smithsonian liked its first system so much that it bought two more - to connect other buildings in Washington.

Bill Price, communications manager at the Smithsonian, is a fan of laser wireless systems: "They're reliable," he says. "Our systems have been up all the time for more than two years, and in that time we've only had two small problems - once, in a heavy fog and once when condensation formed on the window in front of one of the MultiLinks."

Mr Price's experience puts paid to lingering fears that lasers can be temperamental instruments that need constant attention. "Once or twice a year, I check their alignment, but otherwise I don't have to fool with them," he says. "They just keep working."

Lightpointe, which has installed more than 400 systems in 23 countries, also provided the hardware for a network in New York City. There, the New School University was also busting out of its telecom seams. Here, too, a fibre-optic link would have been ideal, but digging up the streets of New York is not the easiest of pursuits and would have made the system prohibitively expensive.

The answer for the university was a system that could communicate at speeds up to 1.25 gigabits (billion bits) per second (Gbps). The university's accountants, who were sending the biggest files, quickly found that files that had taken them minutes to transfer took seconds to reach their destination.

The university now has six units connecting buildings in Greenwich Village and plans to add to the optical network another building elsewhere in the city. The laser links have been so reliable that the university has abandoned two of its radio links.

Soho, in some ways London's version of Greenwich Village, also has laser links running across its rooftops. This time the users are smaller businesses with a need for heavy duty data connections.

As well as its more racy image, Soho is home to a large number of media businesses, including film production, an increasingly computerised process. Sohonet provides a specialised high-speed, high-capacity digital network for the area's media industry. Laser links are a part of this network.

Film and TV producers, post-production facilities and advertising agencies use the network for the electronic exchange of professional quality sound, pictures and internet content.

Gareth Wredden, managing director at Sohonet, says: "One of the great benefits of using a rooftop laser is that the equipment is more efficient than a land-based solution, especially in urban areas such as Soho. It causes less physical disturbance in the area and is far more cost effective, as it removes the need to dig up roads to lay traditional cables."

One customer for Sohonet's laser link is the production company Smoke & Mirrors, which was involved in the latest James Bond movie, among others. Mark Wildig, the company's managing director, is enthusiastic about the speed of the laser link. It has brought instant benefits, he says. "The client can view material in real-time anywhere in the world, meaning the Sohonet technology allows us to concentrate on the creative process and saves us - and the client - time and money."

Mr Wredden of Sohonet makes another point in favour of free-space lasers, the ability to install hardware for one-off projects. An example of this is the ultimate movable feast, the Formula 1 grand prix series which moves from country to country throughout the season. The Benetton Formula 1 team now deploys a laser system supplied by the British company PAV Data Systems, based at Windermere in the Lake District.

Benetton has bought two SkyNet systems from PAV. Weighing 13 kg and set up in minutes, this system can carry data at 100Mbps. The laser provides a link between the team's mobile headquarters and the team in the pit lane. Sensors in each racing car collect all manner of data, on such key variables as water temperature, brake wear, as well as the car's controls and the driver's physical condition.

As the car enters the pit lane, it sends its data over the SkyNet to the garage. Computers turn the data into graphs for the engineers to work on. The lasers also carry the data back to the pit lane for communication to the driver.

"The information relayed by PAV's SkyNet can make the difference between success or failure in a race and most importantly, avoiding an accident," says Pat Symonds, engineering director at Benetton Formula 1. Giancarlo Fisichella benefited from this at last year's Monaco Grand Prix, says Mr Symonds.

The SkyNet system made it possible for the team to detect that something was amiss at the back of the car. The team called in Mr Fisichella for an early pit stop and for remedial work on the problem. Instead of being forced to withdraw from the race, adds Mr Symonds, the driver carried on to claim third place and more valuable points in the Formula 1 season.