Process of adjustment of a continuously tunable light source

A process of adjustment of a continuously tunable external cavity light source, said source comprising:

• a laser controlled by an injected current with an optical axis and a first and a second facet, the first facet having a low reflection coefficient,
• a diffraction grating placed on the axis of the laser, on the side of the first facet, rotatable about an axis intersecting the laser axis at right-angles, and, with the second facet of the laser, forming the external cavity,
• an arm rigidly connected to the grating having a mobile end which is in permanent contact with a slide plane perpendicular to the optical axis of the laser,
• means of fine adjustment of the slide plane with respect to the laser,
• the tunning of the source being achieved by a shifting of the grating, wherein:
• (a) an approximate adjustment is made of the rotation and position of the slide plane,
• (b) the grating is rotated and, simultaneously, the emissive power of the source is measured with respect to the current injected as a function of the rotation of the grating,
• (c) the number of emissive power jumps is counted with respect to the current injected during the rotation of the grating, each jump being given a sign depending on its direction,
• (d) the fine adjustment means are used in accordance with the result of the count,
• (e) operations (b), (c) and (d) are repeated until the count result is zero.