something i didn't realize was a problem until like the last year is that when i say "infrared", half of the people reading it will go "yep, that's right, near infrared in the range of 750 nm to 1500 nm that shows up on silicon sensors" and the other half will go "yep, that's right, far infrared in the range of 1500 nm to 1 mm that shows up on microbolometers" (qualifying it as "NIR" or "LWIR" does not help very much in my experience)
@whitequark✧✦Catherine✦✧ Free-space communication using anything longer than 1.2um (e.g. 1550nm SFP modules) might be quite unlikely to be detected, due to invisibility to Si cameras. The government where I live believes itself entitled to regulate all communication via infrared, but has graciously granted the public a licence to use TV remotes, perhaps to gratify themselves that they are not being disobeyed. The power limit of 125mW probably means that many hot objects are illegal to communicate with.
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