The THAAD interceptor contains a cooled sapphire window?

• A. TRUE
• B. FALSE
• C. NOT APPLICABLE
• D. UNKNOWN

Answer: (A)

The infrared seeker on the THAAD interceptor uses a window that must survive extreme flight conditions while staying transparent to infrared. Sapphire is chosen for that window because it offers excellent IR transmission, exceptional hardness, and strong resistance to thermal and mechanical stress. Keeping the window actively cooled lowers the temperature of the window and the sensor behind it, which reduces thermal noise and self-emission and helps prevent distortion or deformation from the heat of boost and high-speed flight. This combination—a sapphire IR window plus cooling—maintains clear, reliable imagery so the seeker can detect and track the target accurately during the interception phase.