Vohnsen Brian, Rativa Diego
Advanced Optical Imaging Group, School of Physics, University College Dublin, Dublin, Ireland.
J Vis. 2011 Jan 24;11(1):19. doi: 10.1167/11.1.19.
The Stiles-Crawford effect that relates visibility to pupil point is typically expressed by a Gaussian function at any given wavelength of illumination. The pupil location of the maximum and the width of this function refer, respectively, to the pointing and waveguide properties of individual cone photoreceptors. In vision simulations, the function is integrated across the pupil when estimating effective retinal images, but the validity of this approach has still not been unequivocally confirmed. Indeed, aberrations and coherence properties may significantly alter not only the amplitude but also the phase distribution of the light at the retina in a way that differs fundamentally from that of the Maxwellian illumination configuration used when characterizing the effect. Here, we report on an experimental comparison of the traditionally determined Stiles-Crawford function and the equivalent for annular and half-annular apertures using extended highly coherent and incoherent sources. We show that an integrated Stiles-Crawford function is absent for coherent light but remains valid for highly incoherent light at the pupil. The results are supported by numerical evidence for coherent light propagation and are in agreement with a light-coupling understanding of retina photoreceptor waveguides.
将可见度与瞳孔位置相关联的斯泰尔斯-克劳福德效应，在任何给定的照明波长下通常由高斯函数表示。该函数的最大值处的瞳孔位置和宽度分别对应于单个视锥光感受器的指向和波导特性。在视觉模拟中，在估计有效视网膜图像时，该函数会在整个瞳孔上进行积分，但这种方法的有效性尚未得到明确证实。实际上，像差和相干特性不仅可能显著改变视网膜上光的振幅，还可能改变其相位分布，其方式与表征该效应时所使用的麦克斯韦照明配置有根本不同。在此，我们报告了一项实验对比，该对比使用扩展的高相干和非相干光源，对传统确定的斯泰尔斯-克劳福德函数以及环形和半环形孔径的等效函数进行了比较。我们表明，对于相干光不存在积分后的斯泰尔斯-克劳福德函数，但对于瞳孔处的高度非相干光仍然有效。这些结果得到了相干光传播的数值证据的支持，并且与视网膜光感受器波导的光耦合理解一致。
