As the development of single crystal CVD (Chemical Vapor Deposition) lab created diamond progresses, it is slowly replacing polycrystalline CVD diamond as the material of choice for laser optics. One application of polycrystalline CVD diamond optics, as can be seen in Laser Focus World, is extreme ultraviolet lithography. CVD diamonds’ advantages for this application being:
- Low absorption – with a short-wavelength cut-off of around 230 nm
- High fracture strength
- Thermal conductivity at higher than 2000 W/m K
- Low coefficient of thermal expansion
Polycrystalline CVD diamond is limited in terms of the specifications that it can deliver relative to single crystal CVD diamond due to the existence of grain boundaries between the crystals.
Single crystal CVD diamond allows for “New Levels of Performance” when used in optical applications, this Element Six™ white paper provides some examples:
- High Power YAG lasers; Optical windows and lenses
- High Power Solid State lasers; Active optical components (Raman), optical windows and intracavity cooling
- Spectroscopy (both laboratory and on-line); Optical windows, prisms and lenses
- Semiconductor processing and inspection; Optical windows and hemispherical lenses
- Terahertz and Radar applications – Optical windows and prisms
- (Bio)Medical optics; Optical windows, prisms and lenses
- Defense and aerospace (directed energy/imaging); Thermal mounting and optical windows
One of the main challenges of commercializing single crystal CVD lab created diamond applications is the availability and price of the diamond material. Diamond Foundry is currently working on solving that problem and will soon be producing single crystal material at unmatched scale and price.