Page 450 - Introduction to Information Optics

Chapter 8 Information Storage with Optics

1
Suganda Jutamulia and Xiangyang Yang'
'BLUE SKY RESEARCH, SAN JOSE, CA
2
SuN MICROSYSTEMS INC., MCLEAN, VA

8.1. DIGITAL INFORMATION STORAGE

Energy and mass are the fundamental physical quantities. Time and space
are the fundamental physical dimensions. The pattern of the distribution of
energy over time or space generates information. By this definition, any object
continuously generates new information. Energy is transmitted from a source
and finally is detected by a detector. The transmitted energy of desired
information is known as the signal. The detected energy from unwanted
information is called noise. Human beings are the ultimate detector for
detecting information and translating it to meaningful abstract knowledge.
Information storage involves a medium that stores the spatial energy pattern
at a given time, and represents the stored pattern at a later time. A spatial-
energy pattern can always be converted into a temporal pattern by a scanning
process.
As was mentioned by Yu [1], light is not only part of the stream of energy
that supports life, but also provides us with an important source of informa-
tion. Information storage with optics, or simply optical storage, as we use this
term throughout this chapter, is the medium that is able to store the pattern
of light intensity. Upon stimulation, the medium presents back a pattern of
light intensity identical to the previously stored pattern.
As mentioned above, information is a pattern of fluctuating energy. The
signal is the desired information that propagates from one site to another and,

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