Single point diamond turning (SPDT) is a well known method for fabricating micro optics. The big difference between a standard lathe and a single point diamond turning machine is that the SPDT machine uses a diamond tipped bit for its machining and it is able to machine surface finishes of a few nanometers and features that are down to about 1 micron in size. In contrast to the lathe analogy, single point diamond turning can also be used for non-radial symmetrical optics. Examples include: diffractive lenses, fresnel lenses, cylindrical, toric lenses, free form optics as well as conventional (a-)spherical optics.
Single point diamond turning is capable of being used with many different types of non-ferro materials. Some UV plastics do not lend themselves to molding so single point diamond turning is used to actually machine the plastic to its correct shape. Single point diamond turning is also used on metals.
Often when the cavity for a plastics injection mold is needed it will be created using a single point diamond turning machine.
Optics created by this method are used in all kinds of applications. They can be used in astronomy, industry, homeland security and medical applications.
The advantages of using single point diamond turning are: the ability to make lens shapes very accurately without expensive tooling and it is reproducible. The only tooling required for the process is a diamond bit. The process isn’t really suited for mass production; it takes a while to make each individual optic.