Very cheap plastic optical fiber sensors for measurement of displacement without contact

We present an alternative development of very cheap sensors utilizing plastic optical fibers and diode lasers extracted from laser pointers. We have applied these sensors to perform measurements of displacement and distance without physical contact. The development of these sensors started with the characterization and control of these semiconductor lasers. We have achieved to control various diode lasers by means of a current controller, specially designed for this application. In this work, we show two different sensor configurations, getting a measurement range between 1 and 3 mm with microns resolution.