GAS DISCHARGE ULTRAVIOLET WAVEMETER WITH ENHANCED ILLUMINATION

摘要

The present invention provides a wavemeter for an ultraviolet laser capable of long life beam quality monitoring in a pulsed ultraviolet laser system at pulse rates greater that 2000 Hz at pulse energies at 5 mJ or greater. In a preferred embodiment an enhanced illumination configuration reduces per pulse illumination of an etalon by a factor of 28 compared to a popular prior art configuration. Optics are provided in this embodiment which reduce light entering the etalon to only that amount needed to illuminate a linear photo diode array positioned to measure interference patterns produced by the etalon. In this preferred embodiment tow sample beams produced by reflections from two surfaces of a beam splitter are diffused by a defractive diffuser and the output of the defractive diffuser is focused on tow separate secondary diffusers effectively combining both beams in two separate secondary diffusers effectively combining both beams in two separate spectrally equivalent diffuse beams. One beam is used for wavelength and bandwidth measurement and the other beam is used for calibration. In preferred embodiments an etalon chamber contains nitrogen with an oxygen concentration of between 1.6 and 2.4 percent.