Robert Rosenberg

Evolution of strain energy during recrystallization of plated Cu films

The microstructural evolution within plated Cu films has been investigated using high-resolution x-ray diffraction, revealing a change in strain state within the recrystallized grains and the surrounding matrix with time. By approximating the case of an isolated grain in a randomly textured material as an Eshelby inclusion in an elastically isotropic matrix, we can determine the elastic strain energy in addition to the interaction strains that develop within the grain due to the effects of elastic anisotropy. The elastic strain energy density generated by a grain possessing cubic symmetry with arbitrary orientation within an elastically isotropic matrix has been compared to that within a fiber-textured film, revealing that the former case possesses less strain energy. These results suggest that the recrystallization of Cu (111) grains from an electroplated film with a small, initial grain size is less energetically favorable for films exhibiting strong (111) texture than for a randomly textured film. Expe...

Characterization of room temperature recrystallization kinetics in electroplated copper thin films with concurrent x-ray diffraction and electrical resistivity measurements

Concurrent in-situ four-point probe resistivity and high resolution synchrotron x-ray diffraction measurements were used to characterize room temperature recrystallization in electroplated Cu thin films. The x-ray data were used to obtain the variation with time of the integrated intensities and the peak-breadth from the Cu 111 and 200 reflections of the transforming grains. The variation of the integrated intensity and resistivity data with time was analyzed using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. For both 111-textured and non-textured electroplated Cu films, four-point probe resistivity measurements yielded shorter transformation times than the values obtained from the integrated intensities of the corresponding Cu 111 reflections. In addition, the JMAK exponents fitted to the resistivity data were significantly smaller. These discrepancies could be explained by considering the different material volumes from which resistivity and diffraction signals originated, and the physical processes...

Safety and compliance of prescription spectacles ordered by the public via the Internet

BACKGROUNDnThis study investigated prescription spectacles ordered from online vendors and delivered directly to the public for compliance with the optical tolerance and impact resistance requirements for eyewear dispensed in the United States.nnnMETHODSnTen individuals ordered 2 pairs of spectacles from each of 10 of the most visited Internet vendors, totaling 200 eyewear orders. Spectacles ordered consisted of ranges of lens and frame materials, lens styles, and refractive corrections reflecting current distributions in the United States. Evaluations included measurement of sphere power, cylinder power and axis, add power (if indicated), horizontal prism imbalance, and impact testing.nnnRESULTSnWe received and evaluated 154 pairs of spectacles, comprising 308 lenses. Several spectacles were provided incorrectly, such as single vision instead of multifocal and lens treatments added or omitted. In 28.6% of spectacles, at least 1 lens failed tolerance standards for at least 1 optical parameter, and in 22.7% of spectacles, at least 1 lens failed impact testing. Overall, 44.8% of spectacles failed at least 1 parameter of optical or impact testing.nnnCONCLUSIONnNearly half of prescription spectacles delivered directly by online vendors did not meet either the optical requirements of the patients visual needs or the physical requirements for the patients safety.

Evolution of Strain Energy During Recrystallization of Plated Cu Films

Microstructural evolution within thin films is dictated by energy minimization that can arise due to different mechanisms. Conventional treatments that estimate the driving force associated with elastic strain energy often employ a fiber-textured microstructure to arrive at an analytical solution. By approximating the case of a recrystallized grain in a randomly oriented film as an elastically anisotropic inclusion in an elastically isotropic matrix, we can apply Eshelbys inclusion method to calculate both the interaction strains and the strain energy density generated by this elastic incompatibility. A comparison of these two approaches for grains with cubic symmetry reveals that a lower amount of elastic strain energy is generated in the case of an elastically anisotropic grain in an isotropic matrix, suggesting that it is less energetically favorable for Cu (111) grains to recrystallize in films possessing strong (111) texture than in randomly textured films. High-resolution X-ray diffraction measurements are used to extract the difference in the elastic response between recrystallized grains and the untransformed matrix, providing experimental quantification of the induced interaction strains. In addition, the corresponding elastic strain energy values are compared with the appearance of recrystallized (100) grains as a function of film thickness, allowing for a threshold energy density to be extracted. This threshold energy density can be correlated to the difference in surface energy values between (100)- and (111)-oriented grains.

Low Vision Standards

A. Jonathan Jackson is a Hospital Optometrist with over 30 years’ experience in secondary care Ophthalmology/ Optometry. He is currently head of Optometry at the Royal Victoria Hospital, Belfast, Northern Ireland and has gained experience through working in Teaching Hospitals, Universities and Professional Colleges in; Ireland (Royal Victoria Hospital/ Queens University/ Ulster University); England (Moorefield’s Eye Hospital); the USA (University College Berkley) and Australia (Australian College of Optometry/Royal Victoria Eye and Ear Hospital/ University of Melbourne). The experience gained has been through working with many of the world’s foremost ophthalmic surgeons, clinical & research optometrists and vision scientists. He is currently responsible for the delivery and development of adult and paediatric regional contact lens and low vision services, services built on an evidence base and validated against clinical standards. He has a PhD in Corneal Physiology and Morphology and has co-authored many corneal, contact lens, low vision and vision science related publications. He is in addition a Fellow of both the British Contact Lens Association and the American Academy of Optometry. In his current role as a member of the IAPB Low Vision Standards committee he has assisted the team in developing Low Vision Standards suitable for use across the Globe.

Noninvasive assessment of the visual system and ophthalmic and visual optics: an introduction to the joint vision features.

This is an introduction to the joint feature on noninvasive assessment of the visual system and ophthalmic and visual optics.