Page 38 - Chalcogenide Glasses for Infrared Optics

CHAPTER 2

Chalcogenide

Glasses

2.1 Historical Development
The investigation of chalcogenide glasses as optical materials in infra-
red systems began with the rediscovery of arsenic trisulfide glass by
1,2
R. Frerichs in 1950. Good transmission for arsenic trisulfide had been
3
reported in 1870. Development of the glass as a practical optical
4
material was continued by W. A. Fraser and J. Jerger in 1953 at Servo
Corporation. During the 1950–1970 period, the glass was made in ton
quantities by American Optical and Servo in the United States and by
Barr and Stroud in the United Kingdom along with several others in
Europe. The glass was used for commercial devices. As an example,
devices that detected overheated bearings on railroad cars were made
and marketed by Servo Corporation. Hot objects could be detected at
this time by radiation transmitted through the 3- to 5-µm atmospheric
window where arsenic trisulfide glass was transparent. However, the
need for other chalcogenide glass compositions capable of transmit-
ting longer wavelengths arose with the concept of passive thermal
optical systems.
5–7
Jerger, Billian, and Sherwood extended their investigation of
arsenic glasses containing selenium and tellurium, and later adding
germanium as a third constituent. The goal was to use chalcogen ele-
ments heavier than sulfur to extend long-wavelength transmission to
cover the 8- to 12-µm window and at the same time improve physical
properties. In parallel, Russian work at the Ioffee Institute in Lenin-
8
grad under the direction of Boris Kolomiets was reported in 1959.
Work along the same line was begun in the United Kingdom by
Nielsen and Savage 9–11 as well. The Royal Radar work led to limited
production of chalcogenide glass at the British Drug House Laborato-
12
ries. The U.K. results are summarized in a recent book by Savage.
Work at Texas Instruments (TI) began as an outgrowth of the
thermoelectric materials program. The glass forming region for the

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