CO2 and CO laser comparison of glass and ceramic processing

Since the mid-1960s when Kumar Patel invented the 9-10μm CO₂ laser and the 5μm CO laser, the CO₂ laser has experienced tremendous commercial success, while the CO laser has essentially played no role. Until recently, reliable, cost effective, room temperature, long sealed-off lifetime CO laser sources didn't exist. With the product release of Coherent's CO laser family, CO lasers are now commercially available with similar performance to CO₂ lasers. Because certain materials have different absorption coefficients at 5μm and 9-10μm, there is a light-material interaction that is wavelength dependent. In addition, the 5μm beam can be focused to a tighter spot size and for the same spot size, it has a longer depth of focus than at 10μm. This finds relevance in the processing of glass and ceramics where 10μm radiation is absorbed near the surface, but 5μm radiation is deposited into the bulk material and does not rely solely on diffusion from the surface. Leveraging this difference, Coherent and other organizations have conducted experiments comparing CO₂ and CO laser processing of glasses and ceramics. Results show that the CO laser provides processing and performance advantages in this important materials processing market. In this paper, we present the performance characteristics of commercially available CO lasers compared to the equivalent CO₂ laser. Application test results include: straight and curved cutting of various glasses, hole drilling, ceramic scribing, and the emerging area of 3-D glass printing. Both successes and remaining challenges are discussed.