Two-line operation of a TEA CO2 laser with three cavity mirrors

A tunable TEA CO2 laser can be achieved by using three cavity mirrors, one being a half-mirror inserted into the cavity in front of the graving in the grating-output-reflector configuration. Moreover, slight misalignment of this laser system by tilting the grating produces two simultaneously operating laser lines; one line is the 10.6-micron P(20) line and the other is a selected line. The simultaneously operating selected line can be chosen from the various transition bands. This scheme also provides control of the output power ratio between the two lines through tilting of the grating, which also causes a pulse delay.