Page 125 - Chalcogenide Glasses for Infrared Optics

102 Cha pte r F o u r

is shown in Fig. 4.10. It was used to verify and monitor the refractive
index of Amtir 1. Later, when the Army supported the effort for AMI
to become a second source of TI 1173 (Amtir 3), the instrument was
used to verify that the AMI glass met the refractive index standards.
The instrument was also equipped to measure ∆N/∆T. As before, a
hollow copper chamber was mounted with a flat vertical aluminum
mirror attached. But this time, the chamber temperature was controlled
by the flow from a Neslab temperature bath. The ∆N/∆T measure-
ments were carried out beginning as low as possible without frost or
fogging and up as high as 60 to 70°C.

FIGURE 4.10 Photograph of the AMI refractometer combined with the Perkin
Elmer 13 spectrophotometer.