Light- powered gyroscope to be world’s smallest

Gyroscopes are indispensable components in a number of technologies, including inertial guidance systems, which monitor an object’s motion and orientation

Washington, April 3: A pair of light waves may hold the key to creating the world’s smallest gyroscope that is just a fraction of the width of a human hair, according to scientists, including one of Indian- origin.

Gyroscopes are indispensable components in a number of technologies, including inertial guidance systems, which monitor an object’s motion and orientation.

Space probes, satellites, and rockets continuously rely on these systems for accurate flight control.

If the size of an optical gyroscope is reduced to just a fraction of a millimetre, as is presented in the new study, it could then be integrated into optical circuit boards, according to Li Ge, a physicist at the Graduate Centre and Staten Island College, City University of New York. This could drastically reduce the equipment cost in space missions, opening the possibility for a new generation of micro- payloads.

In optical gyroscopes, dual light waves race around an optical cavity or fibre, constantly passing each other as they travel in opposite directions.

Traditionally, engineers have used two approaches to make optical gyroscopes, both based on the Sag nac effect which creates a measurable interference pattern when light waves split and then recombine upon leaving a spinning system.

The first one uses an optical cavity — an engineered structure on a crystal — to confine light and the second one uses an optical fibre to guide light.

The second approach has, to date, been most practical because its sensitivity can be easily enhanced by using longer sections of optical fibre ( some up to five kilometres long).

These lengths of fibre would then be wrapped around an object about five centimetres in diameter, achieving a more manageable size.

Though this system is sensitive to rotation, there are practical limits to how long the fibre can be and how small it can be wrapped before the fibre itself is damaged.

To go truly small, optical cavities seem to be the preferable option, where the Sag nac effect manifests as a subtle colour change.