Patent ID: 8891574
Filing Date: 2014-11-18
Classification: H01S

Abstract:
1. A gas laser comprising: an oscillating laser to output laser light; an amplifying laser containing laser gas and amplifying laser light output from the oscillating laser for output; and a polarization purity control device: the polarization purity control device including: a crystal substrate disposed on a light path of the laser light and tilted with respect to the light path; a polarization monitor to measure polarization purity of the laser light transmitted through the crystal substrate; a rotating stage to rotate the crystal substrate, through a rotation angle, about a crystal orientation axis of the crystal substrate; and a controller to control the rotation angle of the rotating stage based on a result of the measurement from the polarization monitor; wherein the controller is configured to control the rotating stage based on a rotational angle calculated based on a degree of polarization table which depicts the relationship between the rotational angle and a degree of polarization of an incident laser beam after being transmitted through the crystal.