Jessica says the killer used a motorcycle helmet with an infrared visor navigate in the dark studio to commit the murder. There is no such thing as an infrared filter because the human eye cannot see infrared even with a filter in place. The only way to see infrared is with night vision goggles.
Night vision goggles capture the infrared light and direct it to a photo-cathode (like the tube in TV cameras). The photo-cathode collects and converts the photons (light packets) into usable electrons. After the electrons are created, they enter the image intensifier tube (IIT), a type of photo-multiplier. The IIT is what actually accelerates, amplifies, and converts the signal emitted from the electrons back into a usable image by projecting them onto a phosphor screen which emits light when struck by high energy electrons. That image is what you see through the eyepiece.
