Space-qualified CO2laser

The parameters of greatest importance in a laser to be used for communications purposes in a space environment are weight, overall efficiency, ruggedness, and lifetime. We have developed a detailed design that tends to optimize these parameters for a 1-watt, conduction-cooled CO2laser. The laser tube utilizes a metal-ceramic structure for mechanical strength with a coaxial gas ballast reservoir. The electrodes are also designed coaxially for maximum electrical efficiency. Beryllium oxide was chosen as the ceramic material for enhanced heat removal by conduction to a metal heat sink. The warmest spot in the bore (other than the cathode) is only 4°C above the heat sink temperature under maximum power input conditions. The tube uses a 4-mm-diameter bore and has an active length of 16 cm. The ends of the tube are sealed with two gallium arsenide Brewster windows using metal soldering techniques. The mirror cavity is hemi-confocal and utilizes a 7% transmission output mirror (near optimum).