
DIFFRACTION 273
x, cm
y, cm
−1 0 1
−1
−0.5
0
0.5
1
Figure 8.24 Fresnel zone plate. This is the zone plate with a diameter of 2 cm at a distance
of 10 m.
0 5 10
0
0.5
1
u
Zone plate
Figure 8.25 Real field in Fresnel zone plate. This is the cosine integrand from Figure 8.20.
All contributions are positive.
aperture. The irradiance will be a fraction near 1/4 of the maximum at the edge of the shadow,
and will decay rapidly thereafter with very weak fringes. Strong fringes will occur on the bright
side of the shadow line, and their amplitude will decrease moving into the bright region away
from the edge.
8.8.4 Fresnel Zone Plate and Lens
One particularly interesting application ...