What does the specification for polarization of a gas laser mean?

Our Helium-Neon lasers are typically available as either linearly polarized (to a stated ratio) or randomly polarized. Randomly polarized lasers are not "unpolarized". When the laser is first started, the polarization shifting follows a sinusoidal pattern but becomes randomized after warm-up as the effective length of the cavity lengthens and is stabilized. The axis is random, but the polarization state is always linear. For linearly polarized lasers, the ratio represents the amount of light in one polarization axis compared to an orthogonal axis. The plane polarization "E" vector orientation for horizontally positioned rectangular-housed lasers is vertical and for cylindrical-housed lasers it is also vertical, if the laser head is rotated such that the power cable is positioned at 270° (6 o'clock).

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