Method and arrangement for increasing the beam quality and stability of an optical resonator

A method of operating an optical resonator, the method comprising:

• at least one of compensating thermally induced depolarising effects in the optical resonator;
• and
• generating a resonator-internal image rotation, the optical resonator including a plurality of elements reflecting laser radiation including a retroreflective prism configured to effect multiple instances of total internal reflection, the retroreflective prism including
• a first roof edge face pair effecting total internal reflection, consisting of two roof edge faces arranged perpendicularly to one another as a retroreflective part, and
• a second face effecting total internal reflection or a second roof edge face pair effecting total internal reflection, the second roof edge face pair consisting of two roof edge faces arranged perpendicularly to one another in such manner that laser radiation entering the retroreflective prism parallel to an optical axis of the optical resonator undergoes total internal reflection at an angle α on the second face or the second roof edge face pair before undergoing total internal reflection on the first roof edge face pair, and after a further total internal reflection at the angle α on the second face or the second roof edge face pair exits the retroreflective prism parallel to the optical axis of the resonator again, wherein
• the compensating of the thermally induced depolarising effects is effected through the arrangement of the faces in the retroreflective prism that effect total internal reflection and alignment of the retroreflective prism relative to the optical axis of the resonator, and
• the generating the resonator-internal image rotation is effected through the arrangement of the faces in the retroreflective prism that effect total internal reflection and alignment of the retroreflective prism relative to the optical axis of the optical resonator in combination with a further retroreflective prism.