[Wolfess]

I had an 850nm filter on to cut out any visible light as well as an active 850nm IR light source on the tablet and the text still showed up perfectly clear, I even tried it on my older Sony from a long time ago.

The text was still nice and solid black. I didn't know if it still would or not as those black squares style LCD displays on clocks and various instrument displays tend to be invisible or barely visible in IR only due to the lower frequency light passing right though it.

Definitely a niche but interesting additional use for eInk when trying to limit giving off light but go over a checklist or manuals.