Lenses
A lens focuses parallel rays onto a single focal point
•focal
point at a distance f beyond the plane of the lens
–f is a function of the shape and index of refraction of
the lens
•Aperture
of diameter D restricts the range of rays
–aperture may
be on either side of the lens
•Lenses are
typically spherical (easier to produce)
focal point
F
optical
center
(Center
Of Projection)
