An American firm called Catch the Wind hopes to capture the wind industry's attention with a device that measures real-time wind speed and direction as it approaches a turbine. Intended for mounting on the nacelle, the unit is based on light detecting and ranging technology, commonly known as lidar. It projects three laser beams up to one kilometre in front of a wind turbine and measures minor changes in colour frequency caused by the movement of dust particles. Software then uses the Doppler principle to account for changes between the three beams, creating a three-dimensional image of wind speeds and directions. The advantage of the lidar over using conventional anemometers is that pitch and yaw adjustments can happen as the wind changes rather than after it has passed over the turbine, says Catch the Wind. As much as 10% extra yield can be achieved, it adds. The device can also protect a turbine's drivetrain by adjusting the rotor's orientation in advance of wind gusts and turbulence, according to the company, based in Virginia. "I haven't seen any data to verify that it does what it says it will do, but in general, lidar seems to work pretty well," says John Vanden Bosche at consultancy Chinook Wind. Advances in lidar technology for gathering data at potential wind farm sites are demonstrating that it is nearly as accurate at using mast mounted anemometers, he says. Vanden Bosche describes lidar data as "nearly bankable" these days. He expects the Catch the Wind units to be cheaper than the most common on the market -- the Windcube from French Leosphere and the Zephir from the UK's QinetiQ -- which are selling at $150,000-$200,000.