An injection system for a device for depositing thin layers on a substrate by vacuum evaporation, said injection system being intended to be placed in a vacuum evaporation chamber, and said injection system comprising: - a container for receiving a material to be evaporated, - container heating means adapted to evaporate said material, - at least one injection ramp comprising an inner conduit connected to the container so as to receive said evaporated material coming from the container and a plurality of nozzles, each nozzle comprising at least one communication channel between said inner conduit and the outer portion of the ramp, so as to diffuse the evaporated material into said vacuum evaporation chamber to enable diffusion of the evaporated material toward the substrate, characterized in that: - the injection ramp comprises a plurality of injection modules (2a, 2b, 2c, 2d, 2e) mechanically connected to each other in series along a longitudinal direction, each injection module (2a, 2b, 2c, 2d, 2e) communicating via the inner conduit with one or at most two adjacent injection modules (2a, 2b, 2c, 2d, 2e), the container being mechanically connected to a first injection module of said plurality of injection modules at a first end of the injection ramp, the first injection module communicating via the inner conduit with the container, each injection module (2a, 2b, 2c, 2d, 2e) comprising a plurality of injection nozzles, the injection nozzles being distributed with a constant interval between consecutive nozzles so as to obtain a spatially uniform distribution of the injection nozzles along an axis parallel to the longitudinal direction, and - said injection ramp comprises means for adjusting in orientation said injection modules (2a, 2b, 2c, 2d, 2e) about said longitudinal direction so as to align said injection nozzles of said injection modules (2a, 2b, 2c, 2d, 2e) along a line parallel to the longitudinal direction of the injection ramp while ensuring tightness of fixation of said injection modules relatively to the vacuum evaporation chamber. - a container for receiving a material to be evaporated, - container heating means adapted to evaporate said material, - at least one injection ramp comprising an inner conduit connected to the container so as to receive said evaporated material coming from the container and a plurality of nozzles, each nozzle comprising at least one communication channel between said inner conduit and the outer portion of the ramp, so as to diffuse the evaporated material into said vacuum evaporation chamber to enable diffusion of the evaporated material toward the substrate, - the injection ramp comprises a plurality of injection modules (2a, 2b, 2c, 2d, 2e) mechanically connected to each other in series along a longitudinal direction, each injection module (2a, 2b, 2c, 2d, 2e) communicating via the inner conduit with one or at most two adjacent injection modules (2a, 2b, 2c, 2d, 2e), the container being mechanically connected to a first injection module of said plurality of injection modules at a first end of the injection ramp, the first injection module communicating via the inner conduit with the container, each injection module (2a, 2b, 2c, 2d, 2e) comprising a plurality of injection nozzles, the injection nozzles being distributed with a constant interval between consecutive nozzles so as to obtain a spatially uniform distribution of the injection nozzles along an axis parallel to the longitudinal direction, and - said injection ramp comprises means for adjusting in orientation said injection modules (2a, 2b, 2c, 2d, 2e) about said longitudinal direction so as to align said injection nozzles of said injection modules (2a, 2b, 2c, 2d, 2e) along a line parallel to the longitudinal direction of the injection ramp while ensuring tightness of fixation of said injection modules relatively to the vacuum evaporation chamber.