Patent ID: 7593114

Claim:
A device for focusing a laser light beam, comprising: an emission source of a laser light beam along an optical emission path; first focusing means of the laser light beam in a focusing point (F) located at a focusing distance (D); means for adjusting the position of the focusing point (F) relative to the device; and means for detecting the focusing distance (D) active in feedback on the adjustment means, wherein the detection means is optically in between the first focusing means and the focusing point (F) and detects a wavefront radius of curvature of the light beam; wherein the detection means comprises: a glass sheet of predetermined thickness and refraction index, arranged in the optical emission path downstream of the first focusing means and adapted to generate a reflected light beam that propagates along a reflected optical path inclined relative to the optical emission path, the reflected light beam being defined by a pair of light beams partly overlapped and defining an interference region; photodetector means arranged in the reflected optical path and adapted to generate a signal representative of a parameter characteristic of the interference region; and means for processing the signal so as to generate a signal indicative of the wavefront radius of curvature.