Imaging of a plus lens Flashcards
principle of lens operation
2 successive refractions
a lens deviates rays
towards its thicker part
positive radius of curvature
to the right
negative radius of curvature
to the left
larger radius of curvature
smaller curvature
the algebraic sign of the radius of curvature depends on
the orientation of the veto defining the radius of curvature
focal planes
perpendicular to optical axis and the focus
primary focal point for a converging lens +
-principle focus is the point of convergence of a ray bundle parallel to the optical axis
primary focal point for diverging lens -
-the principle focus is the apparent point of origin of an originally parallel beam that when detfracted by the lens becomes parallel
secondary focal point of diverging lens
-the secondary focus is the point that the beam appears to converge prior to being diffracted by the lens-while after diffraction emerges parallel to the optical axis
secondary focal point for converging lens
-the secondary focus is the point of origin for rays that when refracted by the lens become parallel
what is the focal point of the eye?
retina
optical power
P=(n1-n)/R
focal length of lens
P=1/f
- the lens is thin, in other words, we disregard its thickness
- is valid only for rays close to the axis
- the refractive index surrounding both lens surfaces is the same
optical power of the lens
- the sum of optical power of each single refractive surface
- in air P=1/f
- if the lens is surrounding by a medium with n, then P=n/f
