Abstract: A device integrated in a pair of spectacles for the diffusion of virtual images into a user's visual field superposed onto his perception of ambient images. This device includes a display unit and an optical system comprising a mirror and a terminal lens, which comprise virtual image diffusion means, assembled as a prism and attached in a mobile manner laterally to a facial mounting via a chassis which accommodates them in proximity to one another and which is arranged in a dark chamber. These arrangements are such that the virtual images are diffused biased towards the user's pupil from a lateral zone of the mounting, optimizing the use of the light intensity of the display unit.