Laser employing an unstable resonator having an output transmissive mirror

In a laser:

• optical resonator means for excitation with electromagnetic energy for resonance at a resonant optical wavelength and having at least first and second optical reflector means disposed along an optical axis of said resonator means for reflecting resonant optical energy generally along the optical axis to another one of said reflector means;
• laser gain medium means for disposition within said optical resonator means for providing gain to the electromagnetic energy within said optical resonator means at said resonant optical wavelength;
• and
• said optical resonator means comprising a positive branch unstable resonator and wherein said first optical reflector means disposed on said optical axis of said optical resonator means has a first reflective surface for reflecting resonant optical energy to said second optical reflector means, said first reflector surface being partially transmissive for coupling an output beam of coherent resonant optical energy from said optical resonator means through said first partially transmissive surface of said first reflector means as a filled-in beam of generally uniform transverse cross sectional power density.