Nov 28 2007
The researchers are working on a laser-driven motor that may, in future, provide pinpoint mechanical control even in places where electric motors normally do not work.
Hideki Okamura, a physicist at the International Christian University in Tokyo, says that he conceived the idea of making this motor after using laser "tweezers" to move microscopic objects around.
Although the new motor is relatively inefficient in manoeuvring larger things and lacks a reverse gear, Okamura believes that it may find novel applications.
The motor consists of a copper disc with a hole at its centre. A green laser light with a wavelength of 532 nanometres heats up the metal and causes it to expand, producing tiny fast-moving elastic waves on its surface.
The waves move in a circular motion around the centre of the ring. As the ring touches another surface, this motion causes it to move, and when the disc is mounted on a spindle, the movement becomes rotational.
As of now, the motor only turns in one direction. However, the researchers are trying to improve it by using a material that responds differently to two different laser frequencies.
"By changing the timings between the two (pulses), one could reverse the laser motor," Okamura said.
According to him, laser drive could be useful in environments with strong magnetic fields because, unlike conventional electric motors, the laser motor is unaffected by strong electromagnetism.
He further said that the new motor could be used inside MRI scanners or other scientific instruments.
The researchers are now researching into new materials that respond more strongly to laser light.