Page 116 - Chalcogenide Glasses for Infrared Optics

94 Cha pte r F o u r

Amtir 1 Amtir 3 Amtir 6 C1 core
16
15
Str. Pt.
14
T g
13
12
T d SP.
11
Log viscosity (p) 9 8 7 ASTM SP.
10

5 6
Fiber Fiber
4
3
2
1 Cast
0

1.0 1.5 2.0 2.5 3.0
500°C 300°C 200°C 100°C
600°C 400°C
3
1/T × 10 (K)
FIGURE 4.5 Log viscosity versus reciprocal absolute temperature for some
AMI chalcogenide glasses.

The experimental direct measurement of the viscosity of Amtir 3
described in Chap. 3 is shown as a dashed line close to the 1/T line
for Amtir 3. The viscosity data of the dashed line at 575°C indicate a
value of 150 p for casting. Treatment of dilatometer data in this manner
provides a useful guide when using a glass for new applications or
considering the use of a new glass.

4.2 Transmission, Precise Refractive Index, and Thermal
Change in Refractive Index
Transmission and absorption are measures of quality and are therefore
evaluated on each glass plate and recorded. In order for a glass com-
position to be used by designers in production of systems, much more
information concerning the optical and related physical properties
must be carefully measured. Complete characterization is a long and
difficult task.