A laser resonator allows internal optical mirrors to be cleaned easily and minimizes any contamination of the internal optical mirrors. The laser resonator has normally closed cleaning windows disposed immediately in front of output, rear, and folding mirrors for inserting a cleaning instrument therethrough for cleaning these mirrors. A gas inlet discharge tube holder has a discharge tube coupling which interconnects the spaces in parallel discharge tubes for transmitting a laser beam therethrough. The gas inlet discharge tube holder also has a gas flow bypass for bypassing a laser gas that circulates through the discharge tubes. The internal optical mirrors can be cleaned easily with a cleaning instrument inserted through the cleaning windows. As the internal optical mirrors do not need to be removed for cleaning, they and an external optical system are not required to be readjusted for alignment of their optical axes. Any contamination of the internal optical mirrors is minimized because no laser gas flow is caused in the discharge tube coupling.

A gas laser apparatus having transparent laser windows provided on a laser chamber body, in which operating gases is sealed if necessary, comprising circulation means connected to the laser chamber body through an intake port and a discharge port for circulating gases within the laser chamber body and filtration means disposed in said circulation means, further comprising cutoff means for preventing the laser windows from being stained and open and closeably cutting off between the laser chamber body and the laser windows, and having a construction wherein in replacing the laser window, the cutoff means is once placed in a cutoff state, and the laser window is separated from the laser chamber body to place the laser window.

Along an axis (2) of an optical cavity there are: a mirror (3) having a W-shaped cross section to give inner and outer conical reflecting surfaces (4, 6) which are oppositely inclined, a plane mirror (8) having an axial opening and facing the W-shaped mirror (3), a convex mirror (16) receiving the oscillating radiation from the W-shaped mirror (3) via the opening in the plane mirror (8), and a mirror (17) disposed between the plane mirror (8) and the convex mirror (16), said mirror (17) having an aperture and being inclined to the axis so as to extract laser energy from the oscillator.

In a laser device employing an optical resonator which is constructed of a total reflection mirror and a partial reflection mirror, a total reflection plane having an opening is interposed between the partial reflection mirror and the total reflection mirror, the total reflection plane may be formed of, for example, a dielectric thin film or a metallic totally-reflective thin film produced with a cluster ion beam, and the total reflection plane and the total reflection mirror are arranged so as to establish a resonant state. The total reflection plane is formed on an aperture of the partial reflection mirror. The opening of the total reflection plane may be ring-shaped, or a plurality of openings may be provided. The total reflection plane may be located centrally. In a laser device employing an unstable optical resonator, a beam deriving mirror may be disposed within the optical resonator.

The present invention provides systems and methods for filtering particles and assisting gas flow management within laser systems. In one embodiment, a laser apparatus (100) includes an elongate laser chamber defining a chamber cavity (130) and an electrode structure (140) disposed therein. The electrode structure includes an anode (148) spaced apart from a cathode (146). The laser includes an elongate baffle (174) disposed in the laser chamber. The baffle is adapted to arrest a plurality of particles generated within the chamber. In this manner, the baffle operates as a passive filtration system to help filter particles generated within the chamber during laser operation, and may further provide gas flow management capabilities.