Study of Intensity Modulated Fiber Optic Sensor - Effect of Length of Core Exposed in Guiding Liquid

In the past two decades fiber optic technology has passed through many analytical stages. Commercially available fiber optic sensors are widely used in mechanical and industrial automation. They are also used in instrumentation and control. In the present work, an intensity modulated fiber optic sensor is used. A small portion of cladding (1cm, 2cm and 3cm) is removed in the middle of the fiber along its length. This portion is totally immersed in known concentrations of common salt solution which acts as guiding medium. One end of the fiber is connected to source of 820nm, 850nm for plastic fiber and 1300nm, 1550nm for silica glass fiber. The second end of the fiber is connected to a power meter through which the output power is measured. The power loss which is the difference of power launched into the fiber and power collected at the second end of the fiber is noted. A relation between the core exposed in guiding solution and the output power at the second end of the fiber is studied. This study helps in deciding the length of core of an optical fiber to be exposed to the environment.