线偏振器对偏振法折射率测量的影响

在一阶近似下，本文着重分析了偏振法折射率测量中线偏振器漏光误差和转角误差的影响，并导出了有关公式。数据计算表明，当线偏振器位于反射光路中时，转角误差影响最大，若转角误差小于５′时，由此产生的折射率误差约为５．５×１０（－７），此时漏光误差不影响折射率测量精度。当线偏振器位于人射光路中时，若利用中高精度线偏振器（消光比１０（－５）），则由此产生的折射率测量误差约为２．３×１０（－７）。相对该方法的随机误差１０（－５），无论线偏振器位于反射光路或入射光路中，由它产生的折射率测量误差均可忽略不计。

Effect of linear polarizer on index measurement by polarization

Under first order approximation, the effect of the light leakage and the rotating error of the linear polarizer on the index measurement by polarization method is analyzed and some formulae are derived. Numerical calculation shows that the rotating error of the polarizer in reflective light path is larger than that in incident path, if the rotating error is less than 5' the relative index error caused by it in reflective path is about 5. 8 × 10(-8), when the polarizer lies in incident path, its leakage of light has nearly no effect on index measurement; when in reflective path, the index error caused by it is about 2.3 × (10(-7)～10(-9)) using the device with (10(-5)～10(-7) ) of extinction ratio. Compared to the measurement random error (rms ) of the order of 10(-5), the total systematic error caused by the errors mentioned above can be neglect.