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Entrance Window

T-ReCS contains three entrance windows that are interchangeable in real time; the control software selects the window that is best for the specific observation and conditions.

T-ReCS Windows
No.
Material
Anti-Reflection Coating Thickness
(mm)
Transmittance Absorption Coeff. Emissivity Comments
1 KBr No 10 92% @ 2-25 µm 0.0004/cm 0.04% Water soluble
2 ZnSe BBAR
optimized for 10 µm
5.8 >94% @ 2.5-13 µm
>97% @ 8-12.5 µm
0.0005/cm
(+ 2 BBAR)
0.4% Small wl coverage,
Insoluble
3 KRS-5 No 5.9 70% @ 2-35 µm 0.005/cm 0.3% Insoluble

KBr thickness required to hold pressure. ZnSe and KRS-5 thicknesses optimized to match focal shifts with KBR.

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