Seeker window design is a whole branch of missile engineering. Most missles use a quartz window that is sprayed with an evaporative coolant. In more advanced

Seeker window design is a whole branch of missile engineering. Most missles use a quartz window that is sprayed with an evaporative coolant. In more advanced designs the coolant flows through microchannels and then out micro holes on the leading edge, where the coolant evaporates and provides a film cooling. https://www.spiedigitallibrary.org/conference-proceedings-of-spie/4369/0000/IR-window-design-for-hypersonic-missile-seekers--thermal-shock/10.1117/12.445328.short?SSO=1 https://www.spiedigitallibrary.org/conference-proceedings-of...