A model was studied for embedded intrinsic and extrinsic Fabry Perot fiber optic sensors. This model relates the strains and temperature changes in the sensors to the reflected light intensity. The model consists of two parts. Submodel Ⅰ relates the temperature and the strains inside the sensor to the change in sensor length and to the changes in th optical properties of the sensor. Submodel Ⅱ relates the changes in sensor length and optical properties to the changes in the intensity of the reflected light.