Hartmann wave-front measurement at 134 nm with λ_EUV/120 accuracy

Abstract

We report, for the first time to our knowledge, experimental demonstration of wave-front analysis via the Hartmann technique in the extreme ultraviolet range. The reference wave front needed to calibrate the sensor was generated by spatially filtering a focused undulator beam with 1.7- and 0.6-microm-diameter pinholes. To fully characterize the sensor, accuracy and sensitivity measurements were performed. The incident beam's wavelength was varied from 7 to 25 nm. Measurements of accuracy better than lambdaEUV/120 (0.11 nm) were obtained at lambdaEUV = 13.4 nm. The aberrations introduced by an additional thin mirror, as well as wave front of the spatially unfiltered incident beam, were also measured.

Tunable coherent radiation at soft X-ray wavelengths: Generation and interferometric applications

“…This picture is recorded at a wavelength of 2.07nm(600eV) with an exposure time of 1 sec. Note that the rings are smaller at 600eV than 500eV, as in figure 3-7, due to the shorter wavelength and thus reduced divergence angle as seen in equation (3)(4)(5)(6)(7)(8)(9)(10). 46…”

“…This highly absorptive nature, however, creates great difficulties in taking accurate visibility measurements, and thus β, of this material. A density, ρ, of 11.914 (g/cm 3 ) and atomic weight, A, of 114.40 g/mole were used in these calculations. 3 .…”

“…A density, ρ, of 11.914 (g/cm 3 ) and atomic weight, A, of 114.40 g/mole were used in these calculations. 3 . RBS measurement courtesy of Motorola.…”

“…The sample used had a thickness of 350nm and a RBS determined density of 5.891g/cm 3 . Note the increase in the magnitude of the error bars at energies higher than the absorption edge.…”

High harmonics generation: Spatial characterisation and applications

“…The Marechal's criterion [8] stands that a beam is diffraction-limited at a given wavelength, , when the root-mean-square (rms) wave front aberration is lower than /14. EUV wave-front can be reconstructed by several techniques [8,9]. In these experiments we have used the so-called Hartmann techniques.…”