The performance of high-contrast AO instruments (GPI, SPHERE, ScEXAO, MagAO) and other systems that operate at visible wavelengths can be severely hampered by control system latencies and temporal wavefront errors. In high-contrast systems, temporal errors and delays are manifest as high spatial frequency wavefront residuals that scatter light into the controllable region of the PSF and diminish contrast, an effect that is particularly severe when atmospheric coherence times are short. Solutions that have been proposed include lower latency electronics, deformable mirrors with lower mechanical response times, and specialized control algorithms such as predictive control. These advancements will be necessary for achieving the latency goals of high actuator count systems on future Extremely Large Telescopes (ELTs), including NFIRAOS+ and PFI on the Thirty Meter Telescope, upgrading the performance of existing highcontrast systems, and pushing adaptive optics to visible wavelengths. LLAMAS (Low-Latency Adaptive Optical Mirror System) is a fully funded adaptive optics system at the Lawrence Livermore National Laboratory site that will test these techniques in an integrated, real time, closed-loop AO system. With a total system latency goal of ~100 microseconds (including mechanical response time, not including frame integration), LLAMAS will achieve an order of magnitude improvement in AO system latencies over the current generation of high-contrast AO systems. The woofer/tweeter architecture will incorporate a 492-actuator Boston Micromachines MEMS device mapping 24 actuators across a circular pupil. The tweeter mirror will be paired with a specialized low-latency driver, delivering less than 40 microseconds electronic and mechanical latency (10 – 90%). The real-time control computer will utilize the computationally efficient Fourier Transform Reconstructor with a predictive Kalman filter with a goal of completing all computations and reconstructing the wavefront in less than 20 microseconds. LLAMAS will be fully integrated with a 21×21 lenslet Shack-Hartmann sensor by January 2019. These proceedings describe the LLAMAS design, characterize the performance of its low-latency componentry, and discuss the relevance of the design for future high-contrast, visiblelight, and high actuator count AO systems on ELTs.
The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is the first of a kind megajoule-class laser with 192 beams capable of delivering over 1.8 MJ and 500TW of 351nm light , . It has been commissioned and operated since 2009 to support a wide range of missions including the study of inertial confinement fusion, high energy density physics, material science, and laboratory astrophysics. In order to advance our understanding, and enable short-pulse multi-frame radiographic experiments of dense cores of cold material, the generation of very hard x-rays above 50 keV is necessary. X-rays with such characteristics can be efficiently generated with high intensity laser pulses above 10<sup>17</sup> W/cm² . The Advanced Radiographic Capability (ARC)  which is currently being commissioned on the NIF will provide eight, 1 ps to 50 ps, adjustable pulses with up to 1.7 kJ each to create x-ray point sources enabling dynamic, multi-frame x-ray backlighting. This paper will provide an overview of the ARC system and report on the laser performance tests conducted with a stretched-pulse up to the main laser output and their comparison with the results of our laser propagation codes.
X-ray streak cameras are used at the National Ignition Facility for time-resolved measurements of inertial
confinement fusion metrics such as capsule implosion velocity, self-emission burn width, and x-ray bang time (time
of brightest x-ray emission). Recently a design effort was undertaken to improve the performance and operation of
the streak camera photocathode and related assemblies. The performance improvements include a new optical
design for the input of UV timing fiducial pulses that increases collection efficiency of electrons off the
photocathode, repeatability and precision of the photocathode pack assembly, and increase the input field of view
for upcoming experiments. The operational improvements will provide the ability to replace photocathode packs
between experiments in the field without removing the diagnostic from the Diagnostic Instrument Manipulator
(DIM). The new design and preliminary results are presented.
We present the design of a compact UV (263-nm) timing fiducial system for use with x-ray streak cameras at the National Ignition Facility (NIF). The design consists of remote fiber amplification of an infrared 1053-nm (1ω) seed, a free-space optical path that has two stages of frequency conversion from 1ω to the fourth harmonic (4ω), and fiber delivery of the 4ω signal via output fiber for use with an x-ray streak camera. This is all contained within an airbox that can reside in a vacuum. The 1ω seed and the pump light for the fiber amplifier is delivered to the airbox via optical fiber ( 100 meters) from a location in the NIF that is shielded from neutron radiation generated from imploding targets during system shots. When complete, the system will be able to provide timing fiducials to multiple x-ray streak cameras on the same system shot. We will present data that demonstrates end-to-end system performance.*
Implementing the capability to perform fast ignition experiments, as well as, radiography experiments on the National Ignition Facility (NIF) places stringent requirements on the control of each of the beam's pointing and overall wavefront quality. One quad of the NIF beams, four beam pairs, will be utilized for these experiments and hydrodynamic and particle-in-cell simulations indicate that for the fast ignition experiments, these beams will be required to deliver 50% (4.0 kJ) of their total energy (7.96 kJ) within a 40-µm-diam spot at the end of a fast ignition cone target. This requirement implies a stringent pointing and overall phase conjugation error budget on the adaptive optics system used to correct these beam lines. The overall encircled energy requirement is more readily met by phasing of the beams in pairs but still requires high Strehl ratios and root-mean-square tip/tilt errors of approximately 1 µrad. To accomplish this task we have designed an interferometric adaptive optics system capable of beam pointing, high Strehl ratio, and beam phasing with a single pixilated microelectromechanical systems deformable mirror and interferometric wavefront sensor. We present the design of a testbed used to evaluate the performance of this wavefront sensor along with simulations of its expected performance level.
Implementing the capability to perform fast ignition experiments, as well as, radiography experiments on the National
Ignition Facility (NIF) places stringent requirements on the control of each of the beam's pointing and overall wavefront
quality. One quad of the NIF beams, 4 beam pairs, will be utilized for these experiments and hydrodynamic and
particle-in-cell simulations indicate that for the fast ignition experiments, these beams will be required to deliver
50%(4.0 kJ) of their total energy(7.96 kJ) within a 40 μm diameter spot at the end of a fast ignition cone target. This
requirement implies a stringent pointing and overall phase conjugation error budget on the adaptive optics system used
to correct these beam lines. The overall encircled energy requirement is more readily met by phasing of the beams in
pairs but still requires high Strehl ratios, Sr, and RMS tip/tilt errors of approximately one μrad. To accomplish this task
we have designed an interferometric adaptive optics system capable of beam pointing, high Strehl ratio and beam
phasing with a single pixilated MEMS deformable mirror and interferometric wave-front sensor. We present the design
of a testbed used to evaluate the performance of this wave-front sensor below along with simulations of its expected