An affordable smartphone interrogatable polarimetric fiber optic current sensor

In this paper we describe a low cost polarimetric optical fiber sensor based on a BSO magneto-optic crystal and plastic fibers spectrally interrogated with a smartphone. We analyze the spectral and the intensity distortions introduced by the smartphone. The transmission spectra of the RGB filters were measured. Power law dependent distortions of the RGB pixels intensity responses was established. To overcome the jitter and the rescaling problems of the camera a simple scheme for wavelength calibration is proposed and successfully tested. The advantages and issues related to smartphone interrogation vs. spectrometer interrogation are discussed.