Thermal management to reduce focus shift using ZnS MS optics

Abstract

Focus shift or thermal lensing is one of the key factors when determining the quality of a cutting or welding head. High power CO2 laser industry cutting heads evolved over time to produce focused beams with a minimum of thermal lensing. One of the key lens parameters that determine thermal lensing produced by a focusing lens is the lens materials thermal conductivity. CO2 OEM system builders have found that the best optical material for focusing lenses in cutting heads is ZnSe; this is largely due to its relatively high thermal conductivity and low absorptivity. It is expected that the 1 µm cutting heads will evolve in a similar manner with regards to managing the thermal loads in the cutting head including the need for a high thermal conductivity lens material and relatively low absorptivity. In this paper we will present test results for focus shift utilizing direct water cooled mounts with ZnS MS lenses. We will also discuss the effects of beam diameter changes on the focus shift when changing to different magnifications.Focus shift or thermal lensing is one of the key factors when determining the quality of a cutting or welding head. High power CO2 laser industry cutting heads evolved over time to produce focused beams with a minimum of thermal lensing. One of the key lens parameters that determine thermal lensing produced by a focusing lens is the lens materials thermal conductivity. CO2 OEM system builders have found that the best optical material for focusing lenses in cutting heads is ZnSe; this is largely due to its relatively high thermal conductivity and low absorptivity. It is expected that the 1 µm cutting heads will evolve in a similar manner with regards to managing the thermal loads in the cutting head including the need for a high thermal conductivity lens material and relatively low absorptivity. In this paper we will present test results for focus shift utilizing direct water cooled mounts with ZnS MS lenses. We will also discuss the effects of beam diameter changes on the focus shift when changing to diff...