Abstract: A very low energy-absorption coating and related methods for use with high power CO2 lasers includes at least a thin layer of ThF4 (16) used as a water/moisture barrier, in combination with BaF2 (14), for various optical elements. When used in connection with a ZnSe substrate (12) or any other suitable material (such as for a focusing lens), the coating (10) extends the useful life by helping prevent moisture adsorption that otherwise may occur within 2-3 days of contact with air. The coating (10) may comprise (1) a BaF2 layer (14) of approximately optical quarter wave thickness, (2) a thin 200-300 Angstrom layer of ThF4 (16) used as a water barrier (3) a thin 1000-2000 Angstrom layer of ZnSe (18), and (4) an optional ZnSe layer (20) of optical half wave thickness. Among other applications, the coating (10) provides very low energy absorption for a 10.6 um CO2 laser at a value<0.15%, and provides longer lifetimes as compared to conventional coated lenses without the combination of BaF2 (14) and ThF4 (16).

Abstract: A very low energy-absorption coating and related methods for use with high power CO2 lasers includes at least a thin layer of ThF4 (16) used as a water/moisture barrier, in combination with BaF2 (14), for various optical elements. When used in connection with a ZnSe substrate (12) or any other suitable material (such as for a focusing lens), the coating (10) extends the useful life by helping prevent moisture adsorption that otherwise may occur within 2-3 days of contact with air. The coating (10) may comprise (1) a BaF2 layer (14) of approximately optical quarter wave thickness, (2) a thin 200-300 Angstrom layer of ThF4 (16) used as a water barrier (3) a thin 1000-2000 Angstrom layer of ZnSe (18), and (4) an optional ZnSe layer (20) of optical half wave thickness. Among other applications, the coating (10) provides very low energy absorption for a 10.6 um CO2 laser at a value<0.15%, and provides longer lifetimes as compared to conventional coated lenses without the combination of BaF2 (14) and ThF4 (16).

Abstract: A method is described for setting up a system comprising an active medium. The method comprises thermally controlling the system comprising an active medium by radiative cooling. The radiative cooling thereby is based on stimulated and/or coherent Raman scattering processes. In particular embodiments, the thermally controlling may be obtained by tailoring the efficiencies of the Raman scattering processes by optimising at least one of a number of system parameters. The invention furthermore relates to systems thus obtained, to methods for thermally controlling systems comprising an active medium that generate radiation and to computer program products for performing the methods for setting up systems comprising an active medium and thermally controlled by radiative cooling using stimulated and/or coherent Raman scattering processes.

Abstract: Laser cutting method using a CO2 laser light beam focalized by means of a ZnSe-lens system, which involves a laser beam power above 4 kW, using radially or azimuthally polarised laser light.

Abstract: Laser cutting method using a CO2 laser light beam focalized by means of a ZnSe-lens system, which involves a laser beam power above 4 kW, using radially or azimuthally polarized laser light.

Abstract: A lens for laser cutting devices, with improved heat transfer properties, and more particularly a lens having a radius R1+R2, the lens comprising a lens body having a radius R1 and a radial outwardly extending flat flange portion having a radius R2, wherein the ratio of R1/R2 is chosen such that the heat transfer is optimized.