Spatial-frequency response of a photoreceptor and its wavelength dependence. I. Coherent sources.
The response of an isolated model foveal cone to a coherent sinusoidal intensity source is explored with use of the methods of photoreceptor optics. The dielectric waveguide model of a foveal cone that was previously used to explain the Stiles-Crawford effect and its wavelength dependence [Vision Res. 13, 1115 (1973)] is applied to photoreceptor excitation by coherent gratings with variable spatial frequency and light wavelength. The results indicate that the photoreceptors themselves contribute to visual acuity through a wavelength-dependent response at each spatial frequency. In particular, the isolated photoreceptor has a characteristic low-pass spatial-frequency-filter effect for wavelengths between 410 and 654 nm (where two waveguide modes are carried) and a flat response for wavelengths greater than 654 nm (the single-mode region).
Stacey
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Department of Mathematics, Royal Melbourne Institute of Technology, Victoria, Australia.
Pask
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C
D005584:Fovea Centralis; D006801:Humans; D008027:Light; D008433:Mathematics; D008954:Models, Biological; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D014796:Visual Perception