Preface -- Introduction -- Light
Theory -- Light Detector --
Light System Configuration -- Light Processing -- Receiver Circuits --
|I became interested in optical
through-the-air communications around 1980. At that time I was doing research in
high-speed fiber optic computer data networks for a large aerospace company. My research
assignment was to produce a report that made recommendations for the best ways of using
the latest optical fiber technologies to satisfy the increased demands for fast data
transmission in the aerospace industry.
|My research involved pouring through
mountains of technical papers, scientific journals, patents and manufacturer's application
notes. As my research progressed I began to notice that nearly all the optical
communications systems described used optical fibers. Little was being written on the
subject of through-the-atmosphere communications.
|It seemed logical to me that many of the
techniques being used in fiber optic communications could also be applied in
through-the-air communications. I was puzzled by the technical hole that seemed to exist.
This lack of information started my personal crusade to learn more about
communicating through-the-air using light.
|During my studies I reviewed many of the light
communications construction projects that were published in some electronics magazines. I
was often disappointed with the lack of sophistication they offered and usually found
their performance lacking in many ways. Many of the circuits were only able to transmit a
signal a few feet. I thought that with a few changes they could go miles. I was determined
to see how far the technology could be pushed without becoming impractical. So, I took
many of the published circuits and made them work better. I discovered better ways to
process the weak light signals and methods to get more light from some common light
emitters. I found ways to reduce the influence ambient light had on the sensitive light
detector circuits and I developed techniques to increase the practical distance between a
light transmitter and receiver. I also experimented with many common light sources such as
fluorescent lamps and xenon camera flash tubes to see if they too could be used to send
information. To my delight they were indeed found to be very useful.
Today, my crusade
continues. I am still discovering ways to apply what I have learned and I'm still making
improvements. However, after having devoted some 20 years of work toward advancing the
technology I felt it was time to collect what I have learned and pass some of the
information on to others. Thus, this book was conceived.