Abstract

The need¹ to understand the acceptance properties of cones can be addressed by treating them as waveguides carrying modes. The number of modes carried and the extent to which each is excited determines the power presented to photo-pigments.² However the extent to which different modes are excited changes with the exciting field.³ Sources with different spatial frequency or different coherence properties will have different exciting fields. We show that for a sinusoidal intensity source, produced by a pair of plane waves forming a Young’s interference pattern, the power transmitted to the photo-pigments in the outer segment is a function of the spatial frequency of the source, and the number of modes carried. When only the first mode is carried the contrast in the transmitted light is independent of the spatial frequency of the source. When two modes arc carried however the contrast in the transmitted light drops off with increasing spatial frequency up to a cut off, then increases again. These results show how the optical properties of the photoreceptors can contribute to the human visual acuity response curve.

© 1993 Optical Society of America