Controlled caustic generator surface lighting device forming a pattern on a target surface

A vehicle turn indicator luminous device comprising:

• an optical element having a controlled caustic generator surface, the controlled caustic generator surface being a reflecting or refracting surface formed by irregular patterns of bosses and recesses extending in accordance with a given overall shape and having local variations of the given overall shape, the local variations being distributed over the controlled caustic generator surface so as to confer on the controlled caustic generator surface an object pattern, the local variations being such that a majority of the controlled caustic generator surface is smooth and such that for a beam of rays incident on the controlled caustic generator surface, the beam of rays having a given distribution, the controlled caustic generator surface deviates the beam of rays with different orientations as a function of the local variations, thus forming a deviated beam propagating an identifiable propagated pattern over a usable range extending in an upstream direction and at least as far as an optimum propagation distance, the identifiable propagated pattern corresponding to a distorted shape of the object pattern, and
• a mounting part on which is to be mounted a beam generator of rays in accordance with the given distribution, so that the beam of rays are incident on the controlled caustic generator surface, wherein
• the identifiable propagated pattern is projected onto a target surface, which is visible from outside the vehicle turn indicator luminous device and which is situated inside a usable range or at a distance substantially equal to the optimum propagation distance.