CO2 lasers are one of the commonly used lasers in industry and have important applications in processing, communication, radar, chemical analysis, surgery, etc. As the power of CO2 lasers increases, the requirements for the output window become more and more demanding. Currently, the commonly used window materials, ZnSe and GaAs, can be distorted or broken under mechanical stress as well as thermal stress, resulting in window failure and damage.
The high power output requires that the window must have comprehensive performance such as high permeability, high thermal conductivity, thermal stability and mechanical strength. High quality CVD diamond resists laser damage with peak energy up to 66J/cm2 and peak power up to 12.7MW/ mm2, while diamond has high transmittance, very high thermal conductivity and excellent mechanical properties, which makes diamond almost perfectly match the demand of window material for high power CO2 lasers. Diamond substrate has low ability to absorb laser energy, and its high thermal conductivity can conduct the heat away, resulting in low window temperature, low thermal stress, low "thermal lens" effect, and excellent window performance. American General company will make diamond film into high-power laser window sheet, can withstand up to 200KW of CO2 laser output.