Vacuum deposition is a family of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures well below atmospheric pressure (i.e.vacuum). The deposited layers can range from a thickness of one atom up to millimeters, forming freestanding structures. Multiple layers of different materials can be used, for example to form optical coatings.

When the vapor source is a liquid or solid the process is called physical vapor deposition (PVD). When the source is a chemical vapor precursor the process is called chemical vapor deposition (CVD). The latter has several variants: low-pressure chemical vapor deposition (LPCVD), plasma-enhanced CVD (PECVD), and plasma-assisted CVD (PACVD). Often a combination of PVD and CVD processes are used in the same or connected processing chambers.

Vacuum aluminising funrance has a aluminising vacuum chamber which will be used for re-coating telescope mirrors.