Detection principle and verification of non-contact displacement meter with pico-meter resolution

Displacement sensors based on laser or optical fiber technology are recognized for their capacity for non-contact distance measurement based on reflection from an object, but with limited measurement distance and resolution. The other option could be light wave interferometer built with the mirrors on the object. However, long distance measurement requires large laser source with stabilized-wavelength. This report presents another solution: a non-contact grating interferometer displacement sensor that enables pico-meter resolution with a semiconductor laser source.