Phase compensation with rotating quarter waveplate in polarizing beam splitting scheme of laser launched and received in common aperture

The receiving efficiency is alternately varying with the azimuth or elevation of the telescope when laser guide star(LGS) is launched and received in a common aperture of altazimuth coude telescope with polarizing beam splitting scheme, because of the phase difference between the s and p polarizing vector caused by the film on the reflecting mirrors. The phase compensation technology of polarizing beam is researched. A phase compensator made of a quarter waveplate and a Faraday rotator is presented. This copensator can keep the efficiency from degrading by rotating the quarter waveplate. Numerical calculation shows that the received efficiency with effective compensation on the quarter waveplate rotating step 1° could be more than 99.90%. A principle experiment confirms that the rotating