A lighting device comprises a solid optical collimator (6′), the collimator comprises a truncated cap having an inside surface (10′) operating in total internal reflection and having a small base opening into a frustoconical through recess that is coaxial with the cap and at the centre of which a light source (8′) is placed, and having a refractive large base such that incident light emitted by the light source is guided in totality by the inside surface towards the large base of the cap. The recess of the collimator is disposed in the cap in such a manner as to have a small base open and coinciding with the small base of the cap.
