We investigate the variations that occur with changes in the number of layers and with the use of the assist beam
main and assist beam energy on the morphology of HfO2/SiO2 quarter wave stacks deposited by dual ion beam
sputtering. We show how the addition of sequential HfO2/SiO2 bilayers, up to eight, affects the surface roughness
and micro-crystallinity of the top HfO2 layer. We also show that use of the assist source significantly smooths the
surface while simultaneously reducing microcrystallinity. The HfO2/SiO2 structures are very robust and can
withstand fluences in excess of 3 J/cm2 generated by 1ps pulses from a chirped amplified Ti:Sapphire laser.
David Reicher, Martha Navarro, Robin Sydenstricker, Jason Oberling, Micheal Marquez, Julio Villafuert, Albert Ogloza, Joni Pentony, Peter Langston, David O'Conner, Denton Marrs
HfO2/SiO2 and ZrO2/SiO2 high reflectors at 1.064 microns were deposited by pulsed reactive DC magnetron sputtering. These dielectric thin film high reflectors were deposited with and without the use of an electron source. The electron source greatly decreased arcing of the magnetrons during the deposition process resulting in thin films with fewer defects. The high reflectors were laser damage tested at 1.064 microns. The optical properties of the thin film coatings were characterized prior to laser damage testing. Optical characterization techniques included angle resolved scatter (BRDF), total integrated scatter (TIS), and adiabatic calorimetry. The dependence of the laser damage threshold and optical properties on deposition conditions is reported.
Optical fields propagation through the Earth's turbulent atmosphere are subject to time varying phase distortions. These phase distortions place severe limitations on electro- optical systems, such as imaging, tracking and vibrometry sensors. The generation of artificial beacons by laser backscatter (guide stars) for wavefront sensing may not be acceptable and natural beacons for wavefront sensing may not be available. Diversity techniques, however, allow passive wavefront measurement of the aberrated wavefront. This paper reports a phase diversity method based upon the transport- of-intensity equation for recovering phase from irradiance measurements. Digitized intensity data over a rectangular array of data is expanded into Zernike polynomials and a matrix method used to solve the transport-of-intensity equation. The phase diversity technique is evaluated in the pupil as well as the focal plane. Simulation and experimental data is provided.
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