ISP SYSTEM has developed a range of large aperture electro-mechanical deformable mirrors (DM) suitable for ultra short pulsed intense lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations thanks to electromechanical actuators driven by stepper motors. DM design and assembly method have been adapted to large aperture beams and the performances were evaluated on a first application for a beam with a diameter of 250mm at 45° angle of incidence. A Strehl ratio above 0.9 was reached for this application. Simulations were correlated with measurements on optical bench and the design has been validated by calculation for very large aperture (up to Ø550mm). Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for actual MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The MD-AME mirrors can be adapted to circular, square or elliptical beams and they are compatible with all dielectric or metallic coatings.
ISP SYSTEM has developed an electro-mechanical deformable mirror compatible with Ultra High Vacuum environment, suitable for ultra short pulsed lasers.
The design of the MD-AME deformable mirror is based on force application on numerous locations. μ-AME actuators are driven by stepper motors, and their patented special design allows controlling the force with a very high accuracy. Materials and assembly method have been adapted to UHV constraints and the performances were evaluated on a first application for a beam with a diameter of 250mm. A Strehl ratio above 0.9 was reached for this application. Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for standard MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses.
The deformable mirror design allows changing easily an actuator or even the membrane if needed, in order to improve the facility availability. They are designed for circular, square or elliptical aperture from 30mm up to 500mm or more, with incidence angle from 0° to 45°. They can be equipped with passive or active cooling for high power lasers with high repetition rate.
Solid material damaging induced by an intense and short electromagnetic pulse is accompanied by structural modifications, such as solid/solid phase transition, solid/liquid phase transition or ablation. In such an interaction, the energy is mainly absorbed by electrons, and then transferred to the lattice over a 1 − 10 ps time scale. Such out-of-equilibrium physics is the subject of intense experimental and theoretical work, rising fundamental questions about the thermal or non-thermal nature of phase transitions, the softening or hardening of chemical bonds, and the competition between thermal ablation and coulomb explosion. Here, an experimental technique based on pump-probe interfero-polarimetry in reflection, is presented. It allows us to measure the reflectivity and phase shift of an optical probe reflecting on the sample, in both P and S polarization directions, with a sub-100 fs time resolution. The accuracies on phase shift and on reflectivity are 10 mrad and 1%, respectively. These quantities depend on both the sample optical properties (dielectric function) and the heated sample hydrodynamics. Careful comparison of signals in P and S polarizations allows us to distinguish between optical properties and hydrodynamics contributions. Optical properties give information about the dynamics of the electron properties which drive the damage formation, while the hydrodynamic contribution includes sample surface motion and modofication of the electron density profile, at the nanometer scale. This interfero-polarimetry technique was employed to study damage on aluminum induced by an infrared ultrashort laser pulse (800 nm, 30 fs, 1 J:cm-2)
We report a recent experiment where the first hard x-ray beam line, X-ray Pump Probe (XPP) instrument using the
SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) free electron laser, was used to heat thin
foils to high energy densities ~ 107 J/cm3. An intense 9 keV, 60 fs (FWHM) duration beam with energy of 2 - 4 mJ at
the XPP beam line was focused using beryllium lenses to an irradiance approaching 1016 Wcm-2. Targets of 0.5 - 3.5 μm
thick foils of Ag and Cu were studied using a suite of diagnostics including Fourier Domain Interferometry, energy
calorimetry and grating and crystal spectrometers. The experimental details and spectroscopic results from the campaign
will be described. Preliminary results indicate that the target is heated relatively uniformly to a temperature lower than