Zinc selenide (ZnSe) is the material used most frequently because its transparency to infrared CO2 laser beams is high (absorption coefficient is small), and it transmits visible guide light.
Aspherical lenses, plano-convex lenses, or meniscus lenses are used. The longer the focal length is, the larger and longer the spot diameter and focal depth become, respectively. Please choose a lens according to the work piece. When using high pressure gas to assist the cutting process, please choose the thickness according to the gas pressure.
Considering for optical precision, Copper (Cu) and Silicon (Si) are used because they have superior processing characteristics for optical precision and superior heat conductance for cooling efficiency. For parts where adhesion of sputtering is intense, Molybdenum (Mo), which have material characteristics of a high melting point and high hardness, is used.
Various coatings are used on the mirror surface to secure reflectivity and improve polarization control, and improvement of durability. It is necessary to choose a type of coating according to the usage and use environment.
Suitable for focusing high power laser light more than 5kW. Copper (Cu) is used mainly since it is superior in heat conductance and can be processed by ultraprecision cutting. In addition, Aluminum (Al) may be used for parts which need to be lightened. For the surface coating, Gold (Au) is used commonly because it has good reflectivity, heat conductance and durability. In addition, Molybdenum (Mo), which has a high melting point and high hardness as its material characteristics, is used for parts where adhesion back-splatters is drastic.
This is used to change the incident beam diameter to the lens or control beam divergence during long-distance laser beam delivery. It has two types: fixed magnification type and variable magnification (zoom) type.
This lens focuses a laser beam scanned with a scanner, etc. It is used for high speed micro drilling of printed circuit boards, high-speed marking of electronic parts and resin parts, etc.