What is the issue ?
- Scientists have developed the world’s smallest optical gyroscope, a device that helps vehicles, drones and handheld electronic devices know their orientation in 3D space.
About gyroscopes :
- Originally, gyroscopes were sets of nested wheels, each spinning on a different axis. However, today’s cellphones have microelectromechanical sensor, the modern day equivalent, which measures changes in the forces acting on two identical masses that are oscillating and moving in opposite directions.
- These MEMS gyroscopes are limited in their sensitivity, so optical gyroscopes have been developed to perform the same function but with no moving parts and a greater degree of accuracy using a phenomenon called the Sagnac effect, named after French physicist Georges Sagnac.
- As optical gyroscopes are built smaller and smaller, so too is the signal that captures the Sagnac effect, which makes it more and more difficult for the gyroscope to detect movement.
- Up to now, this has prevented the miniaturisation of optical gyroscopes.
The world's smallest optical gyroscope : How it was made possible
- The device developed by Caltech engineers can detect phase shifts that are 30 times smaller than the best systems currently available.
- The new gyroscope is 500 times smaller than the current best device.
- The new gyroscope achieves improved performance by using a new technique called “reciprocal sensitivity enhancement.”
- In this case, “reciprocal” means that it affects both beams of the light inside the gyroscope in the same way.
- Since the Sagnac effect relies on detecting a difference between the two beams as they travel in opposite directions, it is considered nonreciprocal.
- Inside the gyroscope, light travels through miniaturised optical waveguides (small conduits that carry light).
- Imperfections in the optical path that might affect the beams (for example, thermal fluctuations or light scattering) and any outside interference will affect both beams similarly.
- The team found a way to weed out this reciprocal noise while leaving signals from the Sagnac effect intact.
- Reciprocal sensitivity enhancement thus improves the signal to noise ratio in the system and enables the integration of the optical gyroscope on to a chip smaller than a grain of rice.