提高人眼波前传感器信噪比的实验研究

Experimental study of wavefront sensors for increasing signal-to-noise ratios

Hartmann-Shack(H-S)人眼波前传感器噪声主要是角膜的反射光。本文用模拟人眼对消噪声的两种方法进行了实验研究。首先,对使用偏振分光棱镜(PBS)的H蛳S系统,在系统出瞳不变,入瞳变化的条件下测量了对应的信噪比。实验证明:与采用薄半透半反镜相比,在光线斜入射消除PBS内部反射噪声的前提下,该方法可使信噪比提高到11∶1。其次,对离轴入射法进行实验研究,获得200∶1信噪比,最后对上述两种方法获得的光斑点阵进行了比较分析。

The primary factor resulting in the noise of Hartmann-Shack wavefront sensors is the light reflected from corneas. A Hartmann-Shack apparatus with unequal entrance and exit pupil sizes are used to investigate two different ways of reducing noise, by measuring the signal -to -noise ratios in artificial eyes. Firstly, in the case of polarization beam splitters with inner reflection removed, the maximal signal-to-noise ratio is shown to be 11:1, which is much higher than that got by using a traditional pellicle beam splitter. Secondly, the off-axial methods are used and the result is 200:1. The results above and corresponding spots arrays are discussed and illustrated.