DEVICE AND METHOD FOR THE MEASUREMENT OF INCLINATION AND ANGULAR STABILITY OF ELECTROMAGNETIC RADIATION BEAMS, AND FOR THE MEASUREMENT OF A SPATIAL SHIFT OF A FOCUSED ELECTROMAGNETIC RADIATION BEAM

A device 1 for measuring an angular inclination and angular inclination fluctuations of an electromagnetic radiation beam is described. This device is adapted to detect the incidence angular inclination θ and the relative fluctuations Δθ with respect to a nominal axis of propagation of the beam, in a desired detection plane comprising the nominal propagation axis. The device 1 comprises a first screen 11, a second screen 12 and at least one first electromagnetic power and/or energy detector Ps. The first screen 11 comprises a first slit S1 having a first slit dimension d1 along a first direction x1 on a detection plane transverse to the first slit. The first slit S1 is adapted to determine, when crossed by the beam, a diffraction of the beam, so as to generate downstream of the first screen 11 a diffracted electromagnetic field having on the detection plane a diffraction pattern dependent on the aforementioned angular inclination of incidence θ of the beam. The second screen 12 comprises a second slit S2 having a second slit dimension d2 along a second direction x2, parallel to the aforementioned first direction x1 on the detection plane. The second slit S2 is parallel to the first slit S1 in a direction y perpendicular to the aforementioned first and second directions (x1, x2), and is arranged in a selection position (X) on a scale defined on the second direction x2. The second screen 12 is arranged downstream of the first screen, with respect to the propagation of the beam, and is configured to shield the diffracted electromagnetic field with the exception of a transmitted portion of diffracted electromagnetic field, passing through the second slit S2. The at least one first electromagnetic power and/or energy detector Ps is arranged downstream of the second slit S2, with respect to the propagation of the beam, and is configured to detect the electromagnetic power and/or energy of the transmitted portion of diffracted electromagnetic field, dependent from the diffraction figure. This at least one first electromagnetic power and/or energy detector Ps is further configured to generate a first electrical signal Vs, based on the detected electromagnetic power and / or energy. Since the power and/or electromagnetic energy detected by the first detector depends on the geometry, or on the diffraction pattern, of the diffracted electromagnetic field, which in turn depends on the incidence angular inclination θ of the beam in the detection plane, the aforesaid first electrical signal Vs is representative of the angular inclination of incidence θ of the beam in the detection plane. A system and a method for measuring an angular inclination and angular inclination fluctuations of an electromagnetic radiation beam, using the aforementioned device, are also described. A method for measuring a spatial shift s of a focused laser beam, at the focusing point, with respect to a reference optical axis, is also described.