The thermal image clip-on device for existing night vision devices creates an image overlay and thus offers the advantages of both technologies combined in one device. The residual light amplifier allows the user to move freely in the dark and perceive their surroundings (depending on the power of the tube and the residual light available) as in the day. Thanks to the additional thermal imaging channel, objects that stand out from the surroundings based on their temperature can be perceived much earlier and even without any remaining light.