Page 17 - Chalcogenide Glasses for Infrared Optics
P. 17
xvi Intro duction
Wavelength
1 2 3 4 5 6 7 8 9 10111213141516
Water
vapor
Carbon
Relative absorption Ozone
dioxide
Window Window
Primary
atmospheric
constituents
H 2 O H 2 O CO 2 H 2 O O 3 CO 2 H 2 O, CO 2
CO 2
FIGURE I.1 Infrared absorption bands of primary atmospheric constituents for average
conditions at sea level.
Over the years, materials used in infrared systems have included
alkali halides, alkaline earth halides, melt formed semiconductors, vapor
grown fine-grain polycrystalline semiconductors, and chalcogenide
glasses. Each of the crystal materials has some advantages and some
disadvantages that will be discussed toward the end of this book.
However, this book will concentrate chiefly on chalcogenide glasses.
After 17 years at Texas Instruments (TI), the author left in 1977 to found
Amorphous Materials (AMI), a small company dedicated to producing
infrared transmitting glasses for use in infrared optical systems. The
company is still active in developing new glass compositions for new
applications.
Some crystalline materials were produced at AMI. The production
of vacuum float zoned silicon, gallium arsenide, and cadmium
telluride, all useful in infrared technology, will be described. Most of
the early glass work reported here was carried out at TI in government-
sponsored programs as indicated in the references. Discussions of
glasses developed at AMI and their applications will be given. Some
results of infrared techniques applied to semiconductors at TI will be