OPTHER (Optically Driven Terahertz Amplifiers) is a project that has the aim to develop new vacuum devices for amplification of T-rays (Terahertz frequencies). These devices will make possible sophisticated applications with a huge potential in different fields such as aerospace, security, medical applications, diagnostics for art conservation. It is well known in fact that there is for THz radiation, the lack of compact, cheap, powerful and efficient THz sources.