Requirements for long-life microchannel coolers for direct diode laser systems

High power direct diode lasers have made significant impact in the industry as an alternative heat source for material processing. In order, to be readily adopted by the industry they have to show >99% uptimes. One of the much-discussed issues associated with copper based micro channel coolers has been the lifetime of the micro channel cooler in High Power Direct Diode Laser (HPDDL) systems. HPDDLs with micro channel coolers have shown long life in some installations, but have shown to work only a few thousands of hours in others. These have been attributed to the erosion, corrosion, or clogging of the micro channel coolers. This paper will describe the proper design of the water system for use with a micro channel cooled laser system. This paper focuses on the water chemistry and its impact on erosion and corrosion of the copper based micro channel coolers. Using previously reported data; we will give erosion rates for different water chemistries.