Radiation therapy for tumors is that radioactive substances is directly placed in the tumor residual cavity, to avoid the blood-brain barrier and improve local drug concentration.

The prosthetic socket is the most important and important crucial parts in prosthetic, and it is the cavity that joins residual limb and prosthetics.

With the peak-seeking servo-controlled technology based on a residual error, an external optical cavity can keep in resonance with the frequency of Ti-sapphire laser in the experiment.