| This work focuses on the development of evanescent field fiber optic sensors suitable for industrial process monitoring and control. Two separate sensor strategies are explored. First, a general purpose near infrared spectroscopic sensor is developed for the determination of fructose and glucose in high fructose corn syrup. The sensor employs a Fourier transform near infrared spectrometer, and an evanescent field fiber optic sensor which can be immersed in corn syrup to obtain a near infrared spectrum. Calibration for sugar concentration is achieved via partial least squares regression of the derivatized spectra. Second, a pH sensor based on neodymium ions has been developed which takes advantage of neodymium's laser action. A laser diode is used as a radiation source, and a photodiode as the detection system. The fluorescence of neodymium is pH dependent, so the intensity of detected fluorescence can be calibrated for pH. A significant advantage of this sensor is that an optical fiber laser amplifier can be employed to amplify the fluorescence optically prior to detection. Such a sensor can be produced in an all solid state form, reducing cost and increasing durability. |
