US Patent 9711934 Laser apparatus

A laser apparatus may include a first laser resonator configured to generate a laser beam, a first optical element configured to adjust a divergence in a first direction of the laser beam, a second optical element configured to adjust a divergence in a second direction of the laser beam, a measuring unit configured to measure the divergence in the first direction and the divergence in the second direction of the laser beam, and a controller configured to control one or both of the first optical element and the second optical element based on the divergence in the first direction and the divergence in the second direction of the laser beam both measured by the measuring unit.