Patent ID: 7254156

Claim:
A laser, comprising: a laser resonator including a gain-medium, said laser resonator being formed between first and second mirrors and having a longitudinal Z-axis and transverse X- and Y-axes perpendicular to each other and perpendicular to said Z-axis; an arrangement for energizing said gain-medium, thereby causing a beam of laser radiation to circulate in said laser resonator generally in a path along said Z-axis thereof; an optical arrangement for expanding said circulating beam in one circulation direction thereof in said Y-axis of said resonator and correspondingly compressing said expanded beam in an opposite circulation direction of said beam; and a diffraction grating having rulings parallel to a X-Z plane of said resonator and located in said laser resonator in the path of said Y-axis expanded beam, said resonator and said diffraction grating therein being configured and arranged such that said Y-axis expanded beam is incident on said diffraction grating at a compound angle thereto, is diffracted by said diffraction grating onto said first mirror, and is reflected by said first mirror back onto said grating such that laser radiation circulating in said laser resonator is incident on said grating twice per round trip in said resonator and wherein said laser resonator includes a wedge-shaped optical element located in said laser resonator in the path of said expanded beam between said beam expanding arrangement and said diffraction grating, said wedge-shaped optical element having a wedge angle in said X-Z plane of said resonator and being arranged with respect to said diffraction grating and said first mirror, such that said expanded beam is transmitted therethrough, and is incident on said diffraction grating at said compound angle.