共孔径偏振耦合分光的旋转四分之一波片相位补偿技术
Phase compensation with rotating quarter waveplate in polarizing beam splitting scheme of laser launched and received in common aperture
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摘要: 在地平式折轴望远镜中开展自适应光学激光导星实验,研究了共孔径发射接收信标激光束偏振耦合分光效率随望远镜方位角和天顶角变化的补偿技术。提出了一种由四分之一波片和法拉第旋光器构成的相位补偿器,通过旋转四分之一波片以实时补偿由于望远镜旋转导致的光路相位延迟量的变化。数值计算表明,望远镜处于任意方位角和天顶角位置时,通过1°步长旋转四分之一波片,可使补偿后的偏振分光效率理论上达到99.90%以上。实验从原理上定性地验证了该方法的有效性。只要测量出镜面的相位延迟,便可计算得到望远镜处于不同方位角和天顶角情况下有效补偿所需的四分之一波片旋转角度,据此可建立实用的旋转波片偏振补偿装置。Abstract: 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
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