The present invention provides a wavelength-stabilized narrow band excimer laser device which has a discharge tube, a cavity formed of both an output mirror at a front side and a total reflection mirror at a rear side, and a wavelength selective element positioned between the front and rear mirrors, wherein the output mirror, the total reflection mirror and the wavelength selective element are securely fixed on a supporting structure which is mounted via a vibration removing device over a mount on which the discharge tube is mounted so that the output mirror, the total reflection mirror and the wavelength selective element are free from any vibration of the discharge tube. The wavelength selective element comprises at least a prism and at least an etalon wherein the above novel wavelength-stabilized narrow band excimer laser device may further have at least a beam splitter for causing a laser beam sprite, a spectroscope for measuring a center wavelength of the split laser beam, a beam-position detector for measuring a direction of the laser emission, a first driver for adjusting a laser beam transmission angle of the etalon, a second driver for adjusting an angle of the total reflection mirror, and a controller for controlling both the first driver in accordance with variations in the center wavelength of the laser beam measured by the spectroscope and the second driver in accordance with variations in the direction of the laser emission measured by the beam-position detector.

An end-viewed low-pressure gas discharge lamp and an envelope for said lamp having a capillary tube discharge bore for containing an excitable gas in which the capillary tube is in direct contact with a cooling medium. A window of optical quality fused silica, a thin section of bubble and particle free glass blown quality silica or sapphire is disposed on an end of the capillary tube for emitting light from a discharge of the excitable gas. A pair of electrodes are hermetically sealed through the envelope for producing a discharge in the capillary tube between the electrodes. The envelope may include a return path parallel to the capillary tube or a side tube as a means for connecting the two ends of the capillary tubes with the electrodes without obstructing the end view of the discharge. Filling the envelope with an excitable mixture of one or more gases, such as vaporized mercury, to a less than atmospheric pressure, and connecting the electrodes to a power supply completes the lamp. Cooling of the capillary tube may be with air or with water in a jacket surrounding the envelope.