
168 OPTICS FOR ENGINEERS
Normal to
surface
θ
Top viewSide view
y
4
S
P
x
z
Light ray
Figure 6.23 (See color insert.) Angles in the Maltese cross. The left panel shows a side
view with the lens and the normal to the surface for one ray, with light exiting at an angle
of θ with respect to the normal. The right panel shows the angle of orientation of the plane of
incidence, ζ = arctan
y/x
.TheS and P directions depend on ζ. The polarization of the incident
light is a mixture of P and S, except for ζ = 0
◦
or 90
◦
.
origin. At any other location on the lens (x, y), the plane of incidence is vertical and oriented so
that it contains the origin and the point (x, y).