Abstract: The present invention provides an optical disk drive for writing multiple tracks of an optical disk.

Abstract: A method for calculating and correcting an astigmatism error in a charged particle beam system. Images are collected during a single focus sweep of the charged particle beam system. Different orientations of image features, such as lines on a stigmation target, are analyzed. Optimum sharpness or best focus values are obtained as a function of the objective lens settings. Appropriate changes to the settings of the astigmatism correctors are computed by taking a linear combination of optimum sharpness values associated with the different orientations of image features. Proper settings of the objective lens and the astigmatism correctors result in focusing of the beam into a "small" spot. In a scanning electron microscope, for example, two sets of quadrupole compensation coils are typically used as astigmatism correctors.

Abstract: A particle beam column for high-resolution imaging and measurement of topographic and material features on a specimen. The particle beam column includes a particle source for providing a primary beam along a primary beam axis for impinging on the specimen so as to release secondary electrons and backscattered electrons therefrom. The particle beam column also includes an objective lens for focussing the electrons so as to provide a radial dispersion of electrons relative to the primary beam axis, the radial dispersion of electrons including an inner annulus of backscattered electrons and an outer annulus of secondary electrons. The particle beam column still further includes a backscattered electron detector for detecting the inner annulus of backscattered electrons and a secondary electron detector for detecting the outer annulus of secondary electrons.

Abstract: A system for determining whether information broadcast by a general transmitter is relevant to a particular user based on the location, velocity and/or time of an object of interest includes a remote terminal, a general broadcasting unit, a transmitter at the general broadcasting unit for broadcasting messages including a segment comprising a region, a velocity and/or a time corresponding to an event, as well as an event specific tag, and storage for storing selection criteria including current position, time and/or velocity information of the user and/or manually entered data of interest. The selection criteria may also include event specific tags. The receiver at the remote terminal receives the messages from the transmitter at the general broadcasting unit. A navigational receiver may also be used to acquire navigational information from an appropriate external source.

Abstract: An electron detector for use in particle beam apparatus, providing particularly high acceptance of backscattered electrons. The electron detector includes an electron multiplier for detecting electrons and an electrode deployed between the electron multiplier and a specimen. The electrode is biased at a negative potential with respect to the specimen and also with respect to the electron multiplier.