Search

We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh--Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. [c] 2010 Optical Society of America OCIS codes: 050.1965, 240.3990, 240.5770.

The friction generated along the two principal axes of a solid aluminum ellipsoid, when sliding on a rubber substrate is studied, during an effort to quantitatively separate hyseteretic friction from adhesional friction. An experimental approach is presented to show that contact area is dependant upon direction of sliding, which negates the assumptions upon which the original theory was based.

Articles written by R. Friedberg and R.H. Good in the American Journal of Physics focused on the link between the surface charge density functions on a conducting disk and a conducting sphere that has the same charge. Computations show that the same concept applies in the acquisition of the charge densities of both elliptic disks and charged conducting ellipsoids. In addition, the charge distribution of ellipsoids can also be determined using the elliptic disk's principal cross section.