Page 483 - Introduction to Information Optics

468 8. Information Storage with Optics

8.65 A. Partovi, D. Peale, M. Wultig, C. A. Murray, G. Zydzik, L. Hopkins, K. Baldwin, W. S.
Hobson, J. Wynn, J. Lopata, L. Dhar, R. Chichester, and J. H.-J. Yeh, 1999, "High-Power
Laser Source for Near-Field Optics and Its Application to High-Density Optical Data
Storage," Appl. Phys. Lett. 75, 1515-1517.

EXERCISES

8.1 (a) How are binary numbers 1 and 0 represented optically in intensity,
amplitude, phase, and polarization?
(b) How are intensity, amplitude, phase, and polarization representing
binary numbers stored in optical storage?
8.2 In a camera, the focal length of the lens is 5 cm and the diameter of the
stop is 2 cm. What is the diameter of the central spot of the Airy disk
when the camera is illuminated with a collimated beam from a sodium
lamp with A = 589 nm?
8.3 (a) How many bits can be stored in an optical storage of A4 paper size
(21.5 cm x 27.5 cm) using a laser diode that emits light at HeNe
wavelength of 633 nm?
(b) If the capacity of a CD-ROM is 650 Mbytes, the A4 paper size optical
storage is equivalent to how many CD-ROMs?
8.4 (a) Using the same laser diode, how many bits can be stored in a 3-D
3
optical storage having 1 cm volume?
(b) To how many CD-ROMs is it equivalent?
8.5 (a) The resolution of a photographic plate is 1000 Ip/mm. What is the
size of the photosensitive silver halide grain?
(b) If our eyes can see a spot as small as 0.2 mm, at what magnification
we will see the grain structure of the photographic plate?
8.6 (a) Can we use a dichromated gelatin film for photography? Explain why.
(b) Can we use a dichromated gelatin film for optical storage? If no,
explain why not; if yes, explain how.
8.7 (a) In photopolymers, what information of light is stored: Intensity,
amplitude, phase, or polarization of light?
(b) In the same photopolymers, is the information of light stored as the
intensity transmission, amplitude transmission, phase modulation, or
polarization rotation property of the material?
8.8 (a) Do photoresists modulate the phase of light due to their local
thickness or local refractive index?
(b) Why can photoresists coated with aluminum modulate reflected
light?
8.9 What is the advantage of thermoplastic film as compared with dichro-
mated gelatin, photopolymer, and photoresist films?