The focusing efficiency of binary Fresnel zone plate lenses is fundamentally limited and higher efficiency requires a
multi step lens profile. To overcome the manufacturing problems of high resolution and high efficiency multistep zone
plates, we investigate the concept of stacking two different binary zone plates in each other’s optical near-field. We use a
coarse zone plate with π phase shift and a double density fine zone plate with π/2 phase shift to produce an effective 4-
step profile. Using a compact experimental setup with piezo actuators for alignment, we demonstrated 47.1% focusing
efficiency at 6.5 keV using a pair of 500 μm diameter and 200 nm smallest zone width. Furthermore, we present a
spatially resolved characterization method using multiple diffraction orders to identify manufacturing errors, alignment
errors and pattern distortions and their effect on diffraction efficiency.
Scanning hard X-ray nanoprobe imaging provides a unique tool for probing specimens with high sensitivity and
large penetration depth. Moreover, the combination of complementary techniques such as X-ray fluorescence,
absorption, phase contrast and dark field imaging gives complete quantitative information on the sample
structure, composition and chemistry.
The multi-technique “FLYSCAN” data acquisition scheme developed at Synchrotron SOLEIL permits to
perform fast continuous scanning imaging and as such makes scanning tomography techniques feasible in a
time-frame well-adapted to typical user experiments. Here we present the recent results of simultaneous fast
scanning multi-technique tomography performed at Soleil. This fast scanning scheme will be implemented at the
Nanoscopium beamline for large field of view 2D and 3D multimodal imaging.
We report on the design and performances of a test prototype active X-ray mirror developed for the French national
synchrotron radiation facility SOLEIL in collaboration with a French company ISP System. The active mirror uses 11
mechanical actuators: one actuator for the main curvature and 10 actuators along the mirror surface for correction of the
residual shape errors. Its radius of curvature can be adjusted from infinity down to 50 m, with residual slope errors in
correction less than 0.6 μrad RMS over a 300 mm useful length. A dedicated X-ray Hartmann wavefront sensor, based
on YAG:Ce wavelength conversion to visible light, was developed for feedback control of the mirror. Closed-loop
experiments were performed at 10 keV on the Metrology and Tests Beamline at SOLEIL.
We report on the x-ray absorption of Warm Dense Matter experiment at the FLASH Free Electron Laser (FEL) facility at DESY. The FEL beam is used to produce Warm Dense Matter with soft x-ray absorption as the probe of electronic structure. A multilayer-coated parabolic mirror focuses the FEL radiation, to spot sizes as small as 0.3μm in a ~15fs pulse of containing >10<sup>12</sup> photons at 13.5 nm wavelength, onto a thin sample. Silicon photodiodes measure the transmitted and reflected beams, while spectroscopy provides detailed measurement of the temperature of the sample. The goal is to measure over a range of intensities approaching 10<sup>18</sup> W/cm<sup>2</sup>. Experimental results will be presented along with theoretical calculations. A brief report on future FEL efforts will be given.
In this article, a stitching Shack-Hartmann profilometric head is presented. This instrument has been developed to answer
improved needs for surface metrology in the domain of short-wavelength optics (X/EUV). It is composed of a highaccuracy
Shack-Hartmann wavefront sensor and an illumination platform. This profilometric head is mounted on a
translation stage to perform bidimensional mappings by stitching together successive sub-aperture acquisitions. This
method ensures the submicroradian accuracy of the system and allows the user to measure large surfaces with a submillimetric
We particularly emphasize on the calibration method of the head; this method is validated by characterizing a super-flat
reference mirror. Cross-checked tests with the Soleil's long-trace profiler are also performed. The high precision of
profilometric head has been validated with the characterization of a spherical mirror. We also emphasize on the large
curvature dynamic range of the instrument with the measurement of an X-ray toric mirror.
The instrument, which performs a complete diagnostic of the surface or wavefront under test, finds its main applications
in metrology (measurement of large optics/wafers, post-polishing control and local surface finishing for the industry,
spatial quality control of laser beam).
In 2002, first experiments at the Advanced Light Source (ALS) at Berkeley, allowed us to test a first prototype of EUV Hartmann wave-front sensor. Wave-front measurements were performed over a wide wavelength range from 7 to 25 nm. Accuracy of the sensor was proved to be better than λ<sub>EUV</sub>/120 rms (λ<sub>EUV</sub> = 13.4 nm, about 0.1 nm accuracy) with sensitivity exceeding λ<sub>EUV</sub>/600 rms, demonstrating the high metrological performances of this system.
At the Swiss Light Source (SLS), we succeeded recently in the automatic alignment of a synchrotron beamline by Hartmann technique. Experiments were performed, in the hard X-ray range (E = 3 keV, λ = 0.414 nm), using a 4-actuators Kirkpatrick-Baez (KB) active optic. An imaging system of the KB focal spot and a hard X-ray Hartmann wave-front sensor were used alternatively to control the KB. The imaging system used a genetic algorithm to achieve the highest energy in the smallest spot size, while the wave-front sensor used the KB influence functions to achieve the smallest phase distortions in the incoming beam. The corrected beam achieved with help of the imaging system was used to calibrate the wave-front sensor. With both closed loops, we focused the beam into a 6.8x9 μm<sup>2</sup> FWHM focal spot. These results are limited by the optical quality of the imaging system.
Metrology 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 to measure the x-ray laser optical properties. By use of a Michelson interferometer working as a Fourier-Transform spectrometer, the line shapes of different x-ray lasers have been measured with an unprecedented accuracy (δλ/λ~10<sup>-6</sup>). 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. Capillary discharge XRL has demonstrated a very good wavefront allowing to achieve intensity as high 3*10<sup>14</sup> Wcm<sup>-2 </sup>by focusing with a f = 5 cm mirror. The measured sensor accuracy is as good as λ/120 at 13 nm. Commercial developments are under way.