The visualization of the whole eye fundus with enough resolution to discriminate single photoreceptors would be of an enormous interest for understanding retinal diseases and distrophies. In this work, we present a versatile and flexible SLO device that is able to provide high quality images in real time either in large field of view (40ºx30º) or small field of view but with high-resolution (4ºx3º). The combination of an efficient electronics design and the optical system with adaptive optics provides a large set of customization parameters.
In order to provide the end user with a diffraction limited collimated beam, adaptive optics phase correction systems are now a standard feature of ultra intense laser facilities. Generally speaking, these systems are based on a deformable mirror controlled in closed loop configuration in order to correct the aberrations of the beam measured by the wavefront sensor. Such implementation corrects for most of the aberrations of the laser. However, the aberrations of the optical elements located downstream of the wavefront sensor are not measured and therefore not corrected by the adaptive optics loop while they are degrading the final focal spot. We present an improved correction strategy and results based on a combination of both usual closed loop and phase retrieval in order to reach the diffraction limit at the focal spot inside the interaction chamber. The off axis parabola alignment camera located at the focal spot is used in combination of the deformable mirror and wavefront sensor to get images of the focal spot. The residual aberrations of the focal spot are measured by a Phase Retrieval algorithm using the acquired focal spot images. Then the adaptive optics loop is run in order to precompensate for these aberrations, which leads to diffraction limited focal spot in the interaction chamber.
Adaptive Optics is now a standard feature to control the laser beam quality of the high power lasers facilities. The development of the next generation of high power and high brightness laser facilities comes along with the increase of the energy of the laser pulses. In these lasers, the size of the optical elements used at the end of the chain must be increased in order to withstand the higher energy of the laser pulses. Laser adaptive optics systems are based on the use of deformable mirrors and are usually located at the end of the laser chain. Therefore, along with the other optics, the size of the deformable mirror must be increased in order to withstand the energy of the laser.
Mechanical deformable mirror technology is compatible with all the standard high power dielectric coatings and is easily scalable. Large mechanical deformable mirrors able to withstand high pulse energies can be manufactured without technological obstacle. We present characterization and beam shaping results obtained with two large mechanical deformable mirrors. One mirror has a 180mm circular clear aperture. The other is an elliptical deformable mirror with 270 x 190mm clear aperture and is used as a fold mirror at 45° incidence. These large deformable mirrors can withstand pulse energies around 10 kilojoules for chirped pulses. They are compatible with the needs of beam shaping and beam control of the next generation of high power and high brightness laser facilities.
When ultra high intensity lasers facilities were in their early development, the only concern was getting laser pulses with
the right energy and pulse duration. As facilities are orienting toward the end users, they are now required to deliver a
laser beam with additional qualities like a focal spot with constant quality. That is why Adaptive Optics is now a
standard feature for the current ultra high intensity lasers facilities to correct for the aberrations of the beam exiting the
laser chain. However, the very last optical components, like the off axis parabola to focus the beam induce aberrations
that cannot be directly corrected as they are located after the wavefront sensing.
We present a new technology of deformable mirror and a new correction strategy to get optimal focal spot in the
experiment chamber as well as measurement of the actual beam quality in the chamber while the beam is used for
experiments. These deformable mirrors were designed taking into account needs of ultra intense laser applications. They
provide exceptional stability, optical quality and innovative features like scalability and maintenance of the reflective
surface. The method of correction proposed uses usual adaptive optics loop to correct for all the aberration from the laser
chain, as well as additional steps to get an optimal focal spot in the experiment chamber on a non amplified beam, and to
correct and measure the actual beam quality on the amplified beam while it is used for experiments.
We present a Stokes polarization camera prototype based on an electro-optic ceramic (PLZT) as the key
polarization component. Two pairs of electrodes are used to control the applied electric field and so the retardance and
orientation of the induced waveplate. The active area of the PLZT element is 120x120µm. To increase the effective
active area, a 2D array PLZT is used. Imaging through this 2D array with reduced fill factor is achieved by splitting the
focal plane. The focal plane is split by a microlenses array and interacts with each element of the ceramic array. A
modified focal plane is reconstructed by another microlenses array. Digital image processing is used to recover the prime
focal plane information. The technology used in this device (ceramic element, 2D array, imaging with split focal plane)
as well as characterization of the ceramic element and preliminary results will be presented.
We present a linear Stokes polarization camera working at visible wavelength. The camera is both compact and
robust for use in field experiments and outdoor conditions. It is based on fast polarization modulator. Four polarization
states images are acquired successively. Processing software allows live calculation, visualization and measurement of
polarization images deduced from the acquired images. The architecture of the hardware, calibration results and
sensitivity measurements is presented. Polarization image processing including polarization parameters computed are
proposed. These parameters include linear Stokes parameters (S0, S1 and S2), usual polarization parameters (intensity,
degree of linear polarization, and angle of polarization) and other polarization based parameters (polarized image,
depolarized image, virtual polarizer, polarization difference). Color data fusion and vector overlay algorithms are
presented. Finally experimental results and observations as well as possible applications are discussed.