Power of the thermal lens in a laser-pumped forsterite crystal

A modified method is proposed for measuring the properties of an induced thermal lens. The focal lengths of thermal lenses have been measured in forsterite crystals in the (100) and (101) orientations during coherent pumping. These lenses are shown to be astigmatic. The validity of this measurement method and of the theoretical model for determining the properties of induced thermal lenses in Cr:Mg₂SiO₄ crystals has been demonstrated experimentally. For this purpose, the forsterite samples were replaced by a lens of known focal length. In addition, laser experiments were carried out.