Fiber grating sensor design for strain and temperature measurement with optimized intrinsic discrimination: application to liquid composite molding processes monitoring

International audienceIn this work, an optimized strain and temperature sensor has been developed for intrinsic discrimination purpose. It is based on two superimposed gratings: a (short period) fiber Bragg grating (FBG) and a long period grating (LPG) . This design allows a very good spatial resolution with regard to the grating length and a very efficient discrimination by choosing the adapted resonance wavelength of the LPG. The interrogation of the sensor is made by using a supercontinuum white light source and an optical spectrum analyzer (OSA). Sensitivities of both gratings are determined by using a specific calibration bench. Demonstration of our sensor has been done by embedment in a steel specimen submitted simultaneously to strain and temperature