Laser beam characterization by using a Shack-Hartmann sensor

Summary form only given. With the Shack-Hartmann sensor (SHS) an optical wave-front is measured by sampling it with a microlens array. The lateral spot positions produced by each microlens are detected by a CCD-camera and are interpreted as a two-dimensional derivative field of the wave-front. By LSQ-fitting to the discrete derivative fields the wave-front can be reconstructed. Our SHS utilizes a refractive microlens array with a pitch of P-0.15 mm and a focal length of f-4.5 mm. A special algorithm for the attachment of the spots to their reference points allows for the measurement of strong spherical and non-spherical wave-front aberrations. The measured wave-front has an radius of curvature of about R=30 mm the peak-to-valley value of the shown field is about 130/spl lambda/. In many industrial applications the diagnostic of laser beams is very important. The parameter K, the so-called beam propagation factor gives a measure for the cleanness of a given laser beam in the sense of a perfect Gaussian TEM/sub 00/ mode. With the SHS the determination of this parameter is possible if, in addition to the phase reconstruction, the intensity distribution of the beam, i.e., the intensity of the spots is evaluated.