Focusing multiple high-order harmonics in the extreme-ultraviolet and soft-x-ray regions by a platinum-coated ellipsoidal mirror

The focusability of multiple high-order harmonics in the extreme-ultraviolet and soft-x-ray regions is described, together with the design and performance of the ellipsoidal mirror used for this purpose. The mirror focuses intense coherent light in the spectralregion from 25 to 40 nm into a 2.4 (mu)m spot size with a focused peak intensity of 6*10^13 W/cm^2. The focal images indicate that a good beam profile is obtained with a near-Gaussian distribution and a beam quality factor (M^2 value) as low as 2.4.