Most digital cameras have an internal IR cut filter built into the body called a:

Question

Quizplus · Accepted Answer

The correct term for the internal filter in a digital camera that blocks infrared light is a "hot mirror." This is because the filter reflects (or "bounces back") the infrared light like a mirror while allowing visible light to pass through to the camera's sensor. The other choices (proton, casting, buffer zone) are not related to IR cut filters.

Most Digital Cameras Have an Internal IR Cut Filter Built