消除角膜前表面反射杂散光方法的比较

Elimination of stray light reflected from anterior surface of cornea

人眼角膜前表面反射的杂散光是视网膜有效反射率的10～100倍,对人眼波前像差探测和视网膜高分辨率成像影响很大。为了有效消除角膜前表面反射杂散光,本文介绍并对比了偏振分束法、共焦滤波法、细光束离轴照明法和环形照明法等消除角膜前表面反射杂散光的方法。分析表明,这些方法虽然都可以在一定程度上消除杂散光,但均不够理想,而环形照明法和共焦滤波法相结合具有光能利用率高、消杂光效果好、简单易行等优点,是消除人眼角膜前表面杂散光的有效方法。

The stray light reflected from the anterior surface of a cornea is about 10 - 100 times of the effective reflectivity of a retina, which can greatly reduce the precision of eye aberration detection and retinal imaging quality. Therefore, it is necessary to avoid the stray light. In this paper, some methods to eliminate the stray light reflected from the anterior surface of cornea are introduced and compared, such as the Polarization Beam Splitting（PBS） , confocal hole, annular illumination, and the illumination with decentered thin beam. Analyzed results show that although the methods can remove the stray light reflected from the anterior surface of cornea in some degrees, they are not ideal. After analyzing, it is pointed out that the combination of annular illumination and confocal hole is the best, and the method not only has the high light-efficiency, but also is much more effective and handy than other methods.