I'm research assistant at EPFL. My project is the development of new technique for engraving sapphire with high pressure (40 bars up to 500 bars) and temperature (normally: about 300 °C, but can be up max. to 500 °C) water.
The experiment is the following: the sapphire sample and water are put in a gold capsule (perfectly sealed). This capsule reaches high pressure and temp. with an autoclave. The sapphire will be etched when it is submitted to such condition.
The capsule diameter is 4 mm and the length: 5 cm. (see drawing: attachment)
I would like to inspect in real time the engraving rate. The simplest and the most promising way (to my knowledge) to get result is an ultrasonic investigation. (Of course, It also my intention to investigate the physical property of the system) It was recommended to me to proceed with a LiNbO3 transducer. The idea is to get a frequency response spectrum of a continuous ultrasonic waves (-> several MHz). The signature of sapphire engraving is the peek(s) (or eigenfrequencies) which move(s) according to time.
Is it simple or feasible to get engraving depth once we get the eigenfrequency? Is my idea realistic? May I speak to you further about my project? Could you redirect me to people who can help me.