Image Reproduction Integrating System

The Image Reproduction Integrating System, also known as the IRIS, was a device capable of translating thoughts into pictures. The Third Doctor had access to one when he worked for UNIT. He used it on Professor Herbert Clegg to confirm he had telepathic powers. The Doctor and the Brigadier used it to view Clegg's visions of Drashigs and giant spiders. (DW: Planet of the Spiders)

IRIS was similar to, but presumably less advanced than, the Time Lord Thought Channel. (DW: The War Games)