Search

We present Hartmann wavefront sensors as versatile metrology tools to provide real-time characterization and optimization of sources as well as easy, at lambda optical alignment, on a spectral range from EUV to hard X-Ray.

Emergence of ultrafast EUV to X-ray sources, Free Electron Laser, High harmonic generation, betatron and Compton, has opened new paradigms in physical, chemical, biological and medical sciences by either producing ultrahigh intensities or for ultrafast imaging or by enabling pump-probe experiments at new timescales. Most of these experiments require an excellent or at least a properly defined wavefront (WF). A number of WF sensing techniques have been proposed in the X-Rays, including grating-based interferometry, speckle tracking, pencil beam deflectometry, or curvature sensors. Among these techniques, Hartmann WF sensing demonstrated a number of advantages, such as insensitivity to vibrations, achromaticity and very large dynamic range. Furthermore, the phase and intensity maps are directly retrieve and nearly instantaneously without the use of complex and long algorithms. Imagine Optic developed EUV to X-ray WF sensors since more than 15 years taking benefit of decades of experience in the visible range. We will show several experiments using our EUV sensors for metrology and optimization of ultrafast EUV sources. We recently developed a Hartmann sensor in the 5 - 25keV range. The device is based on a custom scintillator-to-detector optical relay system, as well as on an optimal Hartmann array geometry, providing 20µm spatial WF sampling resolution, over a 3x3 mm² pupil. We show the results of first experiments on a synchrotron beamline at 10 keV, achieving 4pm WF repeatability.

Since its creation in 1996, Imagine Optic designed and manufactured high performance Shack-Hartmann wavefront (WF) sensors for many kinds of applications such as telescope alignment, laser characterization, optics qualification or adaptive optics, and for many different fields such as space optics, microscopy, high power lasers or lithography. Since 2003, Imagine Optic is actively developing EUV to X-ray Hartmann WF sensors for applications on metrology beams emitted by synchrotrons, free-electron lasers, plasma-based soft X-ray lasers and high harmonic generation. Our most recent developments include the realization of a EUV sensor adapted to strongly convergent or divergent beams having numerical aperture as high as 0.15, as well as the production of a hard X-ray sensor working above 10 keV, providing outstanding repeatability as good as 4 pm rms. Our sensors have demonstrated their high usefulness for the metrology of EUV to X-ray optics from single flat or curved mirrors to more complex optical systems (Schwarzschild, Kirkpatrick-Baez static or based on bender technology or with activators). In terms of optics qualification is a clear advantage of actually measuring the wavefront at-wavelength. Also, we show active Kirkpatrick-Baez alignment in few minutes using our WF sensor in both manual and automatic loops at the benefit of strong improvement of the beam focalization on the sample. Recently we started developing our own compact deformable grazing incidence mirror bender. We present a review of the developed sensors, as well as experimental demonstrations of their benefits for optical metrology of various EUV and X-ray optics.

Imagine Optic (IO) is actively developing EUV to X-ray wavefront (WF) sensors since 2003 for applications on metrology of EUV to X-ray beams emitted by synchrotrons, free-electron lasers, plasma-based soft X-ray lasers and high harmonic generation. Our sensors have demonstrated their high usefulness for metrology of EUV to X-ray optics from single flat or curved mirrors to more complex optical systems (Schwarzschild, Kirkpatrick-Baez static or based on bender technology or with activators). Our most recent developments include the realization of a EUV sensor adapted to strongly convergent or divergent beams having numerical aperture as high as 0.15, as well as the production of a hard X-ray sensor working at 10 keV and higher energies, providing repeatability as good as 4 pm rms. We present a review of the developed sensors, as well as experimental demonstrations of their benefits for various metrology and WF optimization requirements.

International audience; Diffractive Optical Elements (DOE), that generate a propagation-invariant transverse intensity pattern, can be used for metrology and imaging application because they provide a very wide depth of focus. However, exact implementation of such DOE is not easy, so we generally code the transmittance by a binary approximation. In this paper, we will study the influence of the binary approximation of Continuously Self-Imaging Gratings (CSIG) on the propagated intensity pattern, for amplitude or phase coding. We will thus demonstrate that under specific conditions, parasitic effects due to the binarization disappear and we retrieve the theoretical non-diffracting property of CSIG's.

For more than 15 years, Imagine Optic have developed Extreme Ultra Violet (EUV) and X-ray Hartmann wavefront sensors for metrology and imaging applications. These sensors are compatible with a wide range of X-ray sources: from synchrotrons, Free Electron Lasers, laser-driven betatron and plasma-based EUV lasers to High Harmonic Generation. In this paper, we first describe the principle of a Hartmann sensor and give some key parameters to design a high-performance sensor. We also present different applications from metrology (for manual or automatic alignment of optics), to soft X-ray source optimization and X-ray imaging.