filtre rouge inactinique
/ˈfiltʁ ˈʁuʒ inaktinˈik/
n
English: red safelight filter · 红色安全灯滤光片
Sens：Colored filter placed under the lens to frame or focus a black and white image directly onto photographic paper without exposing it.
English: red safelight filter · 红色安全灯滤光片