Waterdrop-shaped micro-displacement sensor with high sensitivity and wide displacement variation range

A new type of waterdrop-shaped micro-displacement sensor is proposed with high sensitivity and wide displacement variation range. A piece of commercial single mode fiber is bent into waterdrop shape with two ends of the fiber firstly passed through two metal micro tubes adhered side by side to one microstage, and then both adhered to another microstage. Interference was created at the output port of the sensor due to fiber-bending-induced birefringence. As a result, high displacement sensitivity of 556 nm/mm over a large displacement variation range of 2.08 mm is achieved by use of this type of sensor. The system is very simple and low cost.