Lecture 7 Flashcards
what is the optical axis?
a straight line that enters and leaves the system -connecting centers of curvature = line of rotational symmetry
what is the visual axis?
line connecting fovea and fixation point, passing through nodal points = projection of fovea into object space
what is the pupillary axis?
line normal to cornea, passing through center of pupil and center of curvature of the cornea
what is the line of sight?
line connecting nodal point passing through pupil center = path of foveal chief ray from fixation point
what is the achromatic axis?
line connecting nodal point and center of pupil = path of chief nodal ray
what is the fixation axis?
line joining object of regard with center of rotation of the eye
what are the 2 necessary changes in the reduced eye from the real eye’s reference axes?
the fovea was moved higher to show there is a difference in axis position and it shows the iris (to show center of pupil)
why are nodal rays important?
they are undeviated
why are chief rays important?
they tell us where the center of the blur disk is located
what is the PLS (line of sight)?
a chief (pupil) ray from the object being viewed through the entrance pupil and exit pupil to the fovea
how are the visual axis, PLS, and fixation axis related in distance vision?
they are all parallel outside the eye in distance vision (parallel incident ray paths from the distant object of regard)
what axis are most optical instruments aligned with?
the pupillary axis
where is angle alpha?
the angle formed at the first nodal point by the eye’s optical and visual axes (about 5 degrees)
where is angle kappa?
between pupillary axis and visual axis
where is angle lambda?
between pupillary axis and line of sight
