格兰-付科棱镜光强透射比曲线波动成因的研究

随空间入射角的连续变化,格兰-付科棱镜的光强透射比曲线会产生较大的波动。为了抑制这种波动,利用偏振光实验系统对格兰-付科棱镜的光强透射比进行了实验,并在假设棱镜空气隙间存在多光束干涉的条件下,对棱镜的光强透射比实验的过程进行了数值模拟。模拟结果和实验结果吻合的非常好。首次相对定量地给出了格兰-付科棱镜的光强透射比曲线随入射角变化而波动的根本原因。并提出了两种抑制格兰-付科棱镜光强透射比曲线波动的方法。结果表明,产生波动的原因是由于棱镜在充当检偏器的过程中,随着步进电机的转动,光束在空气隙上的入射角不断变化,引起空气隙间干涉光束光程差的变化,进而影响多光束干涉加强或减弱而产生的。曲线上的波动较大的原因来自于格兰-付科棱镜的透射光束在切割面上是入射面的s分量,其光强反射比较大的缘故。这一结果对研究具有光强透射比曲线波动抑制功能的格兰-付科棱镜是有帮助的。

Study of transmittance fluctuation of Glan-Foucault prisms

With continuous change of the incidence angle, the transmittance of a Glan-Foucault prism fluctuates a lot. In order to suppress such fluctuation, experiments were carried out for measurement of the transmittance of the Glan-Foucault prism based on a polarized light experimental system. The transmittance was simulated under the assumption that there was multiple beam interference between the prism air gaps. Simulation results and experimental results matched very well. The relative quantitative reason of the transmittance fluctuating with the incidence angle was put forward for the first time. Two methods were proposed to inhibit the fluctuation. The results showed that the reason of fluctuation is the strengthened or weakened multiple beam interference induced by the change of path difference of interference beam between the air gap with the rotation of the stepping motor with the prism as depolarizer. The fluctuations are stronger just because the transmitted beam for the Glan-Foucault prisms is s component on the incident plane which has greater reflectance. The study is helpful for suppressing the transmittance fluctuation of a Glan-Foucault prism.