PHYSCI 173 Lecture Notes - Lecture 5: Ommatidium, Eye, Visual Acuity
21 Apr 2021
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Document Summary
It works best in bright light because there has to be enough light to enter the lens to excite the rhabdom or the fused rhabdomeres. The acuity of the opposition eye is the angle drawn on the figure. In nocturnal animals, there is a clear zone between the lenses and the receptor layer. They are separated from one another with a completely transparent clear tissue. The advantage of that is that now this increases the chances of collecting light. In the dark, there are fewer photons, so now the eye effectively opens up and one receptor can look out at the world through many lenses and increase the chances of collecting photons. The acuity of the superposition eye for one receptor is drawn on the figure. The superposition eye trades acuity for sensitivity. Any one receptor has a much higher chance of collecting photons, and therefore increases the sensitivity to low light, but that trades off visual acuity.
