Page 486 - Introduction to Information Optics

Exercises

is the approximate diameter of the beam at the adjacent layer? What is
the approximate ratio of the area at the focused layer to the adjacent
layer?

NA=0.45

50

.24 To read a page memory in photon-gating 3-D optical storage, the sheet
of light is formed by focusing a collimated light using a cylindrical lens,
as shown in the following figure.
(a) Show that the 3-D storage capacity is limited by the depth of focus
of the focusing cylindrical lens.
(b) If the depth of focus is ad, where d is the layer thickness, and the 2-D
2
storage density is 1 ^m ~ , what is the maximum 3-D storage capacity
3
of a cube of 1 x 1. x 1 mm ?

Cylindrical Lens

1 mm

1 mm
.25 Based on Exercises 8.23 and 8.24, explain why for photon-gating 3-D
optical storage we prefer high NA for the write-in and readout spherical
lenses, and low NA for the activation cylindrical lens.