Therefore, we can deposit thick coatings at higher growth rates. The hardest natural material known, diamond has excellent electrical, mechanical and optical properties, and is also radiation resistant and biocompatible. Thin diamond films have numerous applications, for example as cutting tools, radiation resistant windows for spacecraft, ophthalmic lenses, biomedical implants, microelectronic circuits and engine components. For this, a continuous argon ion laser beam of wavelength 514nm is coupled with a microscope objective lens and passes through a 2mm thick aperture window before focusing on the surface of the substrate. The microscope allows researchers to view the laser direct-write process directly during deposition.
Researchers can also rotate the substrate material to allow the laser access to the lower surfaces.
The film characteristics depend on the process parameters, which have to be optimised to obtain the best quality. The initial stage is to make a pre-form of the object to be created from a suitable material such as polycarbonate, which can be dissolved away after deposition. Layer thickness is built up to about 10mm, which can support the structure. All the locations of the pre-form must be accessible to the laser beam. Often, several steps are required to deposit onto surfaces not directly accessible.