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TUFTRAN®
Zinc Sulfide Layered on Zinc Selenide
Infrared
transmissive windows are currently used at the entrance apertures of many
airborne reconnaissance or navigation systems.The window material must not
significantly decrease the incoming signal or render the signal noisy, and
it should be strong enough to resist dust and rain erosion encountered during
high speed flight. Zinc Selenide (ZnSe) with its excellent transmission in
the infrared is an ideal candidate for this application, however, ZnSe is
a “soft” material (hardness = 110 knoop, flexural strength = 8000
psi) which does not effectively resist rain and dust erosion during high speed
flight. Zinc Sulfide (ZnS) does not have the superior optical properties of
zinc selenide, but it is a “harder” material making it much more
capable of withstanding adverse environmental conditions.
Summary:
Description
TUFTRAN® infrared material consists of
a polished ZnSe window over which a ZnS layer is chemically vapor deposited.
This 1 mm thick layer of ZnS protects the ZnSe window and enhances the material’s
environmental durability making it better able to resist rain, dust, and dirt.
TUFTRAN® features the wide band (1-14 µm) imaging characteristics
of zinc selenide and the mechanical robustness of zinc sulfide. The resulting
material offers high hardness, excellent imaging characteristics, non-hygroscopicity,
and ease of fabrication.
Available Forms
TUFTRAN® has been custom ordered in plates
up to 24 inches in diameter. Blanks are fabricated according to customer specified
surface area and zinc sulfide thickness. A minimum ZnS layer of about 1 mm
is recommended
Transmission
| Properties: |
|
| Thickness of zinc sulfide | |
| Prior to grinding | 0.100 - 0.125" |
| Plate glass polished state | 0.060" + 0.005" |
| Final Condition | 0.04" |
| Modulus of rupture (ZnS/ZnSe) | > 7500 psi |
| Modulus of elasticity (ZnS/ZnSe) | ~ 8.41 x 106 psi |
| Hardness of ZnS layer | > 200 Knoop |
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