Abstract: A window assembly for a laser uses a uniaxial crystalline material such as quartz for the window, secured directly in a hard seal to a metal tubular end component. In order to avoid significant differential thermal expansion between the quartz window and the end component, the quartz crystal is cut in a Z-normal configuration, whereby the thermal expansion and other physical properties of the window are isotropic in the plane of the window. The ability to make a reliable direct seal to a metal component offsets any disadvantages of the Z-normal configuration thought to be controlling in the prior art. Through the disclosed method for assembling and mounting the window, reflection loses are reduced to a practical minimum comparable to that of any preferred conventional window orientation.

Abstract: Method and apparatus are disclosed in a frequency controlled tunable laser system which may be tuned selectively by an operator to any predetermined output radiation frequency within its operating range and servo-locked to maintain that output frequency, for rapidly and automatically maintaining and reacquiring a predetermined output radiation frequency despite momentary interruptions or perturbations of laser oscillation.