New techniques for the measurement of x-ray beam or x-ray optics quality

Abstract

ABSTRACTMetrology of XUV beams and more specifically X-ray laser (XRL) beam is of crucial importance for development of applications. We have then developed several new optical systems enabling tomeasure the x-ray laser optical properties. By use of a Michelson interferometer working as aFourier-Transform spectrometer, the line shapes of different x-ray lasers have been measured with anunprecedented accuracy ( GOO ~10 -6 ). Achievement of the first XUV wavefront sensor has enable to measure the beam quality of laser-pumped as well as discharge pumped x-ray lasers. Capillarydischarge XRL has demonstrated a very good wave front allowing to achieve intensity as high 3*10 14 Wcm -2 by focusing with a f = 5 cm mirror. The measured sensor accuracy is as good as O /120 at 13 nm. Commercial developments are under way.Keywords: x-ray laser, longitudinal coherence, Michelson soft x-ray interferometry, EUV optics 1. INTRODUCTION Since the early development of laboratory x-ray lasers, the ach ievement of applications has been considered as the main objective. Most recently, the emergence of several X-ray laser facilities (COMET, JAERY, LASERIX) strongly reinforced the actual trend to use x-ray lasers (XRL) for appli cations but with a versatility comparable to visible laser one. However due to the wavelength shortening, the development of applications requires to have better and betterXUV optics (wavelength range 10-60 nm typically), from individual mirrors to more sophisticated set-ups likeinterferometers. A novel trend appears very recently with XRL facilities : on-line metrology of x-ray laser beam. Due to the diversity of applications, the metrology must cover a wide range of beam parameters from shot-to-shot energy up to