Research On Ultrasound Detecting Techniques Based On Optic-fiber Gratings

Recent years, with increasing output power of diagnosis ultrasound ,and broadly using high intensity treatment ultrasound (including ultrasound operation ,ultrasound detritus, ultrasound heat treatment, et al),it is extremely urgent to detect accurately the distributing ultrasound field in body. Usually, the ultrasound field in human body is reckoned by complicated theoretical model, but ultrasound field in body may be come from non-ideal sources, and many factors can influence the ultrasound field while spreading through tissues, so it is extremely important to study a new menthod for directly detecting the ultrasound field .Optic-fiber gratings sensor is one of the most interested sensors being studied, it has many advantages as high sensitivity and precision, safe latent, anti electric magnetic interference, highly insulated, endurable of high temperature ,endurable of eroding, low mass, low volume, flexible, broad frequency. Optic-fiber gratings sensor is very convenient for application .By drawing or stressing the optic-fiber gratings, or changing the temperature, the period and reflectivity index of optic-fiber gratings are changed, and so the optic-fiber gratings reflect wave length is changed. Based on those characters, the optic-fiber gratings is made into stress sensors, temperature sensors, pressure sensors, accelerate sensors and so on.By analyzing the theory of fiber gratings wavelength demodulation and the realization of six types of demodulation systems, synthetically considering the characters of detected signals, we selected the transmission model of Fiber Bragg Grating sensing system to detect ultrasound. The system was divided into three parts and the related design ways were presented. The first part was to select an immersed and focused ultrasound piezoelectric transducer to generate focused ultrasound field through characterizing the waveform, field parameters, transducer, and detecting principle of ultrasonic waves. We presented the ultrasound generating system, which was experimentally proved the existence of ultrasound and the place of the focused point as a...