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Design and calibration of a fiber optic hydrophone for underwater shock wave characterisation
The goal of this project is to design and manufacture an optical fiber hydrophone. The student will test and calibrate the prototype by measuring the pressure waveform of laser-induced underwater shock waves. Results will be contrasted to the ones collected with a conventional PVDF hydrophone.
Keywords: Sensor, Laser, Hydrophone, Shock wave
Shock waves are a type of sound wave, characterized by a steep, almost discontinuous increase in pressure. They are distinguished from linear pressure waves when their pressure fronts move at supersonic speeds in a fluid, applying a considerable push on the liquid located in their path. They can be generated in fluids by explosions, laser optical breakdown or simply when an object travels at speeds greater than the speed of sound of the medium and their high energies can consequently have destructive consequences. Shock waves have been applied to industrial processes such as surface cleaning of nanometric particles on silicon wafers in air, where the generated pressure is strong enough to remove tungsten particles in the outer area of the laser-irradiated spot.
Lately, optical fibre hydrophone systems, based upon the use of a Fabry Perot polymer film sensing interferometer have been developed. In comparison to the usual piezoelectric PVDF sensing elements, which are widely used for characterising medical and industrial ultrasound fields, they offer a small effective radius of their single mode fibres which can be inexpensively replaced. They can also be self-calibrated and allow the user to run simultaneous temperature and pressure measurement, while being immune to electromagnetic interferences.
Shock waves are a type of sound wave, characterized by a steep, almost discontinuous increase in pressure. They are distinguished from linear pressure waves when their pressure fronts move at supersonic speeds in a fluid, applying a considerable push on the liquid located in their path. They can be generated in fluids by explosions, laser optical breakdown or simply when an object travels at speeds greater than the speed of sound of the medium and their high energies can consequently have destructive consequences. Shock waves have been applied to industrial processes such as surface cleaning of nanometric particles on silicon wafers in air, where the generated pressure is strong enough to remove tungsten particles in the outer area of the laser-irradiated spot. Lately, optical fibre hydrophone systems, based upon the use of a Fabry Perot polymer film sensing interferometer have been developed. In comparison to the usual piezoelectric PVDF sensing elements, which are widely used for characterising medical and industrial ultrasound fields, they offer a small effective radius of their single mode fibres which can be inexpensively replaced. They can also be self-calibrated and allow the user to run simultaneous temperature and pressure measurement, while being immune to electromagnetic interferences.
The goal of this project is to design, build and calibrate a fiber optic hydrophone. It will then be tested on shock waves and various pressure waves. Direct comparison with an available PVDF hydrophone will help validating results from the prototype.
The goal of this project is to design, build and calibrate a fiber optic hydrophone. It will then be tested on shock waves and various pressure waves. Direct comparison with an available PVDF hydrophone will help validating results from the prototype.
For additional information, the candidates can contact Guillaume Bokman via email (bokmang@ethz.ch)
For additional information, the candidates can contact Guillaume Bokman via email (bokmang@ethz.ch)