Laser line width is the frequency span of the actual laser radiation. This is determined in part by the laser gas temperature, optical resonator, and the laser’s mode of operation. In Access Laser temperature stabilized (-S) models, this can be as narrow as 100 kHz or less at any moment. Gain width is the frequency span of the CO2 molecule, and is determined primarily by the laser gas composition. This may range from 100 MHz to 250 MHz.

•In a typical ALC –S model there are many spectral lines, which are approximately 0.02µm apart. They are a similar shape to the red curve in the graph above.

•When the laser radiates it will select one of the lines. The line width of the laser radiation is indicated by the blue curve.
•When the laser is stabilized, it will remain in one spectral line for hours.
•The exact location of the lasing frequency within the gain width of a stabilized laser can drift a few MHz every 5-10 minutes, but at any instant is less than 100 kHz.
•The laser line width (indicated by the blue curve) can be significantly broadened by not running the laser in CW mode, but modulated with a PWM signal at varying duty cycles.

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