Beam quality measurements with Shack-Hartmann wavefront sensor and M2-sensor: comparison of two methods

Abstract

In both scientific and industrial laser beam applications is essential for users to know what could be expected from the laser beam. That is why analysis of the laser beam parameters is very important during laser use in various industrial and scientific applications. To describe the beam one can use a beam quality factor <i>M²</i> that characterizes the degree of imperfection of a laser beam. There are many methods of beam quality determination. The most common way is to use a device based on techniques described in the International Standard ISO11146 "Test methods for laser beam parameters: Beam widths, divergence angle and beam propagation factor". For example we can use M2-sensor that we design and produce in our Lab. The measurement of the beam quality factor according to ISO11146 is not a simple procedure and might take a long time. And for some applications fast beam quality determination is needed. Moreover sometimes it is not necessary to know the exact value of <i>M²</i>, only estimation of <i>M²</i> is just needed. And for the beam quality estimation we suggest to use Shack-Hartmann wavefront sensor. With this sensor we can easily and fast measure the wavefront of the beam and then according to the wavefront calculate <i>M²</i>. The comparison of two sensors is presented. Advantages and disadvantages are pointed out.