This PDF file contains the front matter associated with SPIE Proceedings Volume 6584, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

GSI Darmstadt currently builds a high-energy petawatt Nd:glass laser system, called PHELIX (Petawatt High-Energy Laser for Heavy-Ion Experiments). PHELIX will offer the world-wide unique combination of a high current, high-energy heavy-ion beam with an intense laser beam. Aberrations due to the beam transport and due to the amplification process limit the focusability and the intensity at the target. We have investigated the aberrations of the different amplification stages. The pre-amplifier stage consists of three rod-amplifiers which cause mainly defocus, but also a small part of coma and astigmatism. The main amplifier consists of five disk amplifiers with a clear aperture of 315 mm. These large disk-amplifiers cause pump-shot aberrations which occur instantly. After a shot, the disk amplifiers need a cooling time of several hours to relax to their initial state. This limits the repetition rate and causes long-term aberrations. We will present first measurements of the pump-shot and long-term aberrations caused by the pre- and the main amplifier in a single-pass configuration. In this context, we will present the adaptive optics system which is implemented in the PHELIX beam line and discuss its capability to compensate for the pump-shot and long-term aberrations.

The laser Megajoule (LMJ) project was launched in 1995 by the French Atomic Energy Commission and is aimed at developing a facility to achieve inertial confinement fusion. The LMJ architecture is based on 240 laser beamlines to be focused onto a millimetre size target. To meet this challenge, one of the main issues consists in a proper control of the quality of the beam wavefront at the output of the laser. For this purpose, the LMJ makes use of a large-size adaptive mirror (named M1 in the actual laser baseline), with 400 by 400 mm² useful aperture. This paper provides an overview of the M1 prototype, using 39 mechanical actuators. This mirror was made by the French company CILAS© together with the help of ISP© for the mechanical actuators. CEA, Cilas and ISP have joined their efforts to complete the overall design. The prototype has been tested on the Laser Integration Line (LIL). This facility is fully consistent with the LMJ requirements, a complete laser chain which comprises 4 beamlines. After presenting the basic design principles, we focus on the demonstrated performance measured on a dedicated setup, as well as on LIL facility.

In this paper we describe the experimental validation of the technique of correction of wavefront aberration in the middle of the laser amplifying chain. This technique allows the correction of the aberrations from the first part of the laser system, and the pre-compensation of the aberrations built in the second part. This approach will allow an effective aberration management in the laser chain, to protect the optical surfaces and optimize performances, and is the only possible approach for multi-Petawatt laser system from the technical and economical point of view. This approach is now possible after the introduction of new deformable mirrors with lower static aberrations and higher dynamic than the standard devices.

We present a novel architecture of deformable mirror dedicated to lasers. The new monomorph mirror presents the advantage of avoiding high spatial frequency on the residual wavefront enabling propagation of the laser beam without any energy modulation. The obtained residual wavefront is 3.4 nm rms wavefront.

Adaptive Optics systems are now working successfully on all major optical telescopes. The sky coverage of these systems is severely limited by the need for bright guide stars, and Laser guide stars have been under development since they were proposed in the 1980s. Laser guide star assisted AO has recently been commissioned at major observatories, and is finally starting to perform well enough, and reliably enough to provide for astrophysical results. The state of the art in astronomical adaptive optics is reviewed here, with emphasis on laser guide star systems. The prospects and challenges of adaptive optics and laser guide stars on the next generation of 'Extremely Large Telescopes' are also examined.

We present the results of our first experimental tests of the concept of an alternative wavefront sensor for extended, incoherent light sources such as the sun. This concept is not associated with subapertures and therefore does not suffer from involved restrictions. In theory, this wavefront sensor also needs very little light from the telescope. The sensor employs a liquid crystal display as used in digital video projectors for masking an image plane in an aberrated telescope. We describe a laboratory setup and an advanced prototype used at the German Vaccum Tower Telescope (VTT), Tenerife.

There are data evaluation of the astronomical optical systems and description of their transfer characteristics presented in this paper. The real data from the BOOTES (Burst Observer and Optical Transient Exploring Monitor)⁷ experiment and from double-station video observation of the meteors are analyzed. The BOOTES is a system for monitoring the optical transient of GRB (Gamma Ray Bursts). The main goal of the double-station video observation of the meteors is acquiring of meteors video records and their analysis. Precision of image data post-processing and analyzing, which is very important for these systems, decreases because of a lot of different kinds of optical aberrations and distortions. It proves itself at most on the frontier of the field of view (FOV). This paper includes the description of astronomical data analysis methods and their demos for different values of distortion. There is also a relation between high order aberrations influence and astrometry measurement precision discussed in this paper.

This paper presents an application of adaptive optics principle onto small sample of liquid surface tension measurement. The principle of experimental method devised by Ferguson (1924) is based on measurement of pressure difference across a liquid sample placed into small diameter capillary on condition of one flat meniscus of the liquid sample. Planarity or curvature radius of the capillary tip meniscus has to be measured and controlled, in order to fulfill this condition during measurement. Two different optical set-ups using liquid meniscus micromirror property are presented and its suitability for meniscus profile determination is compared. Meniscus radius optical measurement, data processing and control algorithm of the adaptive micromirror profile set are presented too. The presented adaptive optics system can be used for focal length control of microsystems based on liquid micromirrors or microlenses with long focal distances especially.

The Scanning Helium Atom Microscope is a new technique currently under development which has potential to become a powerful tool in life science, material engineering and other fields of science. One of the most important components of the microscope is a specially shaped mirror that focuses the helium atom beam onto a sample's surface. The mirror quality affects the diameter of the focused beam and consequently the microscope resolution. Thus, the mirror surface roughness and its shape must be controlled accurately. The mirror is formed from a very thin Si crystal membrane that is deformed under a precise electric field. The Si membrane production process is a complex issue and it is very difficult to obtain membranes of uniform thickness: some remaining thickness variations are always present. These variations affect the mirror shape generated by the electrostatic field and prevent optimal focusing of the helium beam. Here, our aim is to characterize the typical thickness variations observed in membranes. We find that whilst the perfectly symmetric membrane is very difficult to produce, it is possible to define criteria for the selection of the best subset of membranes from a larger production run. Our characterization and selection via "symmetry descriptors" will ultimately diminish aberrations in He focusing. In the paper, the "symmetry descriptors" will be defined, rationalised and discussed in detail.

A tracking system utilizing tunable liquid lens is proposed and demonstrated. Adapting the concept of EWOD (electrowetting-on-dielectric), the curvature of a droplet on a dielectric film can be controlled by varying the applied voltage. When utilizing the droplet as an optical lens, the focal length of this adaptive liquid lens can be adjusted as desired. Moreover, the light that passes through it can therefore be focused to different positions in space. In this paper, the tuning range of the curvature and focal length of the tunable liquid lens is investigated. Droplet transformation is observed and analyzed under a CCD camera. A tracking system combining the tunable liquid lens with a laser detection system is also proposed. With a feedback circuit that maximizing the returned signal by controlling the tunable lens, the laser beam can keep tracked on a distant reflected target while it is moving.

Liquid-crystal (LC) based micro-displays can be used to modulate incoming light waves with respect to amplitude, phase and polarization. Twisted-nematic LC displays produce a combined phase-polarization modulation so that it is difficult to achieve pure phase modulation without amplitude modulation. We present a new phase-only modulating LCOS (Liquid Crystal On Silicon) spatial light modulator (SLM) based on an electrically controlled birefringence (ECB) liquid crystal mode. The device has a HDTV (1920x1080) resolution and a small pixel pitch of only 8&mgr;m (87% fill factor) on a digital silicon back plane. The LC molecules are aligned parallel to the electrodes and an applied electric field forces them to tilt towards the direction of the field. This leads to a pure phase modulation with a phase retardation of 2&pgr; for wavelengths between 420 and 1064nm, with negligible polarization change (<1%) if the light is linearly polarized parallel to the director axis of the LC molecules. The shape of the back-plane of the LCOS micro-display was investigated using a Twyman-Green interferometer and the observed deviation from a plane surface was compensated by addressing the inverse spatially resolved phase retardation function. The interferometer was then used to measure wave fronts that were generated with the micro-display, representing optical elements like e.g. single lenses, lens arrays and tilted mirrors.

Due to the improvements in design and manufacturing technologies, new lenses with complex shapes are continuously appearing in the market. The fabrication of free-form lenses depends mainly on the possibility of measurement. A sensor with simultaneously a large dynamic range and good resolution becomes essential to be able to produce complexshaped lenses with high quality. Regarding this purpose, we propose an adaptive optics (AO) system to measure with a good resolution lenses that have a complex shape. The AO system consists in a novel Shack-Hartmann wavefront sensor based on a cylindrical microlens array, and a liquid crystal programmable phase modulator (PPM) as an active device within an open-loop configuration. The original wavefront from the lens to test is compensated with the PPM in order to decrease its complexity. Subsequently, the compensated wavefront can be measured by the sensor with good accuracy. The wavefront generation performance of the PPM was analyzed in order to evaluate its suitability for open-loop compensation, and a very good correlation between the theoretical wavefront written on the PPM and the measured wavefronts has been obtained for the different amounts of aberration studied. To validate the working principle of the complete setup, an spherical ophthalmic lens with a strong curvature that exceeds the dynamic range of the sensor was successfully measured.

We present an adaptive and dynamic hexagonal electro-optic phase array. The proposed device consists of a 2-dimensional hexagonal array of periodically inverted ferroelectric domains, along the z-axis, in lithium niobate crystals. The phase step is achieved via the application of an external electric field, along the z-axis, through transparent electrodes. Thanks to the electro-optic effect the phase step can changed with continuity over all the 0 to 2π by applying a variable voltage. In this way different patterns can be generated. In fact, one important property of this new proposed configuration of array illuminator is the intrinsic flexibility. Such flexible array could be potentially used in a variety of applications such as optical interconnects, tunable lithographic masks, 2D optical trapping and assembling of particles or wavefront phase modulators. As example, photolitography experiments are performed by means of this optical phase mask with electrooptically tunable phase step. In fact, the collimated beam of an argon laser passes through the phase mask and the near field intensity patterns, at different planes of the Talbot length and for different values of the applied voltage, are used for photolitographic experiments.

The wavefront aberrations in the 100 TW laser pulses are measured and corrected to improve the intensity distribution of the focal spot. Before correcting wavefront aberration of the laser pulses, the laser pulses have higher-order aberrations such as coma, trefoil, and spherical aberration as well as defocus and astigmatism. The wavefront aberrations in the laser pulses are corrected by the deformable mirror. The dynamic and static corrections are tested with the deformable mirror. When correcting wavefront aberrations with the deformable mirror, the focal spot having a 1.2 times spot size of the diffraction-limited focal spot is observed.

A computational model, which describes EM field formation in a pulsed laser from a randomly generated initial spontaneous field inside the laser cavity has been developed. The model is based on a two-dimensional fast Fourier transform and describes a real laser system taking into account a lensing and a diaphragm effect of the laser rod. The laser cavity is described by five effective planes, which represent different laser cavity elements-the back and the front mirror, the Q-switch element and the laser rod. At each plane the EM field is calculated in real space and propagation between the planes is achieved in Fourier space by multiplication with an appropriate phase factor. The computational time needed for simulation of a realistic pulse formation is in order of minutes. The model can predict the shape and the integral energy of the pulse, its transverse profile at different distances from the front mirror (including near and far field) and beam divergence. The results of the model were found to be in good agreement with measured parameters for a Q-switched ruby laser system running in stable as well as unstable cavity configurations. The temporal shape of a laser pulse was measured and calculated not only for the ruby laser, but also for a Nd:YAG laser. It was found that FWHM of a pulse produced by ruby laser is three times longer than FWHM of a pulse produced by Nd:YAG laser.

One way to achieve fusion in laboratory consists in heating and compressing, by using a laser, a capsule containing a deuterium - tritium mix. Achievement of such a project can be obtained only through the development of a new generation of laser facilities. With this end in view, CEA is developing the "Laser Mega-Joule" (LMJ), a facility made of 240 laser lines. The "Ligne d'Intégration Laser" (LIL) is a prototype of the LMJ made of a four laser lines assembly. Presently operational, it must permit the validation of the technological choices that have been made. Particular attention must be given in the achievement of the alignment of the target compared with the laser beams: it must be positioned at the center of the target chamber with a precision better than fifty micrometers rms. The quality of this alignment must be guaranteed in order to ensure the success of the physics experiments performed on the facility. We are presenting the device that has been devised to reach this objective: the "Système de Visualisation de Cible" (SYVIC) or target viewing system. This device is made of two optical visors set on the target chamber, associated with a complicated three-dimensional reconstruction algorithm. It permits to position an object at the center of the chamber, rapidly and with the required orientation. It also makes possible the alignment of all the plasma diagnostics, mounted on the chamber wall in order to study the plasma created by the laser-matter interaction. The first plasma experiment using the SYVIC alignment device took place at the beginning of 2007 with a specific target. Doing so we qualified the accuracy of this device and its implementation on LIL.

The CEA is currently developing the "Laser Mega Joule "(LMJ), a facility capable of concentrating an extremely high quantity of energy from 240 laser beams on a micro target for a brief moment. The characteristics of the facility have been defined to obtain the temperature and pressure conditions required to reach thermonuclear combustion. The "Ligne d'Intégration Laser" (LIL) is a facility designed to validate the choices adopted for the LMJ. It consists of a basic laser line from the MJL with four identical beams. On the LIL, an experiment consists of a series of laser/material interaction firings. For a given firing, there is a concatenation of the phenomena from the triggering of the physical mechanisms to the recording of the signals on the recording instruments (diagnostics). The interaction gives rise to plasma. One sure method to enable the reconstruction of the events in the course of the experiments involves recording an optic time fiducial signal on the main instruments. This temporary marking makes it possible to reposition in time the signals recorded on the measuring instruments against a point of reference. We present here a prototype that has been developed for the time fiducial of the visible streak cameras : "SYMOD : SYstème de Marquage Optique par Diode laser". The original architecture of the bench is based on the use of one laser diode per diagnosis to be marked. Other components, including synchronization equipment and two chronometry arrays, are arranged around this source which constitutes the main component of the device. Tests have been run to validate the technical choice of the source and to demonstrate that the main time requirements concerning the fiducial are met (rise time < 50ps and time jitter < 16ps rms).