Biomedical subjects

Masud Mansuripur

Publications and source records attributed to Masud Mansuripur.

22 records · Page 2Linked to original sources

PubMed2002

Thermal properties and crystallization dynamics of a phase-change alloy for write-once optical data storage.

Using a two-laser static tester, we measured the crystallization temperature and the thermal conductivity of a phase-change alloy thin film used in write-once-read-many media of optical data storage. The experimental technique, in general, and the calibration procedures, in particular, are described. The measurement results are used as entry points into numerical calculations that ultimately yield estimates of the material parameters. Valuable information about the dynamics of mark formation (i.e., localized crystallization) in amorphous phase-change alloy films is obtained from the observed variations of the sample reflectance under short-pulse and long-pulse recording conditions. The dependence of these reflectance variations on the laser pulse power has also been investigated.

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PubMed2002

Intensity, polarization, and phase information in optical disk systems.

Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk.

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PubMed2002

Measurement of the thermal coefficients of rewritable phase-change optical recording media.

We describe a method to estimate the heat capacity of the substrate, the dielectric layer, and the phase-change layer of phase-change optical recording media as well as the thermal conductivity of the phase-change layer in its crystalline state. Measurements were carried out on spinning disks with the beam of light focused and locked onto the groove track. The method relies on the identification of the solid-to-liquid phase transition that occurs in the phase-change layer and takes advantage of the dependence of thermal diffusion on track velocity and irradiation time.

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PubMed2002

Optical characterization of multilayer stacks used as phase-change media of optical disk data storage.

We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

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