The Stéréotéle­scope is a very par­tic­u­lar stereo­scop­ic binoc­u­lar intend­ed for the visu­al­i­sa­tion of pro­ject­ed stereo­scop­ic images and their result­ing dimen­sions. The con­struc­tion was realised by the com­pa­ny Mat­tey père & fils, co-sig­na­to­ry of the patent. The Stéréotéle­scope was pre­sent­ed to the French Soci­ety of Pho­tog­ra­phy dur­ing the ses­sion of Decem­ber 4, 1903.
The Stéréotéle­scope presents itself as an ordi­nary stere­o­scope on which the frost would have been exchanged for optics with a vary­ing dis­tance. When the gap of the diver­gent eye­pieces is the same as that of the lens­es, we are in the pres­ence of a sim­ple the­atre binoc­u­lar. If we decen­tralise the lens­es to give them a greater gap than that of the eye­pieces, the lens­es no longer work through their cen­tre but act­ing as prisms to divert the images, each in an oppo­site direc­tion, this makes it pos­si­ble to arrive at the super­po­si­tion of two stereo­scop­ic images and to have sub­se­quent­ly, the sen­sa­tion of the relief in the same way as in an ordi­nary stere­o­scope, with in addi­tion a strong mag­ni­fi­ca­tion. Dur­ing the First World War, the device found med­ical use for the exam­i­na­tion of the stereopho­tos of the wounded.
(from: Moulin­ier et al. His­toires de vision­neuses stéréo­scopiques français­es. Limo­ges, 2025, p. 103. Author’s translation.)