Development of a low-cost optical fibre colour and displacement sensor measuring instrument

This paper discuss the development of a prototype low-cost portable optical fibre measuring instrument. The instrument employs optoelectronics devices such as light emitting diodes (LEDs) as light sources and semiconductor photodiode (PD) as a photodetector. A fibre optic cable is used as an information signal transmission medium between the light sources, sensors and photodetector. The study focus on the sensors and optical link fabrication and also creating internal reference to correct the variations in light signal intensity due to fibre bending, fibre connection, components degradation and environmental effects. The instrument system has been designed to measure colour variations and physical displacements. It also has computer interfacing facility to linearise the data and create the colour coding.