Abstract: Embodiments of the invention are directed to systems and methods for accurate positioning of a unit movable by a drive system. The method may include adjusting tension of a resilient element of the drive system to reduce hysteresis motion errors of the resilient element below a predetermined threshold by performing measurements of the hysteresis motion errors of the resilient element for two or more tension values and selecting a tension value for which the hysteresis motion error is below the threshold.

Abstract: Embodiments of the present invention are directed to a system and method for controlling fabrication of three-dimensional objects, layer by layer, the system comprising a printing assembly, including an irradiation unit and a printing head, the printing assembly is movable between a printing area and a service area. A light sensor positioned at the service area to measure output radiation power of the irradiation unit at a printing plane and a controller to receive information from the sensor and to automatically adjust electrical power supplied to the irradiation unit based on the information.

Abstract: Method and apparatus for polymerizing photoactive materials included in a liquid material by electromagnetic radiation, by dispensing the liquid material layer-wise into a container and irradiating the accumulated layers by a curing radiation, wherein a substantial part of the radiation is well transmitted through the photoactive material.

Abstract: Data is written on a plurality of data tracks on an optical disk by a plurality of laser beams. The spots illuminated by the beams are spaced apart to prevent thermal interference. The spots are aligned along a line at an angle to the tangent of the data tracks. The angle of the line of spots is determined by an equation using variables that include the track pitch, the minimum distance between spots and the difference in track numbers between tracks being written.

Abstract: Data is written on a plurality of data tracks on an optical disk by a plurality of laser beams. The spots illuminated by the beams are spaced apart to prevent thermal interference. The spots are aligned along a line at an angle to the tangent of the data tracks. The angle of the line of spots is determined by an equation using variables that include the track pitch, the minimum distance between spots and the difference in track numbers between tracks being written.

Abstract: Data is written on a plurality of data tracks on an optical disk by a plurality of laser beams. The spots illuminated by the beams are spaced apart to prevent thermal interference. The spots are aligned along a line at an angle to the tangent of the data tracks. The angle of the line of spots is determined by an equation using variables that include the track pitch, the minimum distance between spots and the difference in track numbers between tracks being written.

Abstract: Apparatus for optical assessment of a sample includes a radiation source, adapted to generate a beam of coherent radiation, and traveling lens optics, adapted to focus the beam so as to generate first and second spots on a surface of the sample and to scan the spots together over the surface. The distance between the first and second spots is responsive to a pitch of a repetitive pattern of the sample. Collection optics are positioned to collect the radiation scattered from the first and second spots and to focus the collected radiation so as to generate an interference pattern. A detector detects a change in the interference pattern.

Abstract: An apparatus and method for focus error detection operable to receive light reflected from an inspected object and to determine a focus error on a surface of the inspected object, the focus error detection apparatus including optics and at least one detection apparatus, whereas the optics and the at least one detection apparatus define at least a first focus error detection path and a second focus error detection path, the first focus error detection path detects focus errors with a greater sensitivity than the second focus error detection path, while the second focus error detection path detects focus errors over a greater focus error range than the first focus error detection path.

Abstract: An apparatus and method for focus error detection operable to receive light reflected from an inspected object and to determine a focus error on a surface of the inspected object, the focus error detection apparatus including optics and at least one detection apparatus, whereas the optics and the at least one detection apparatus define at least a first focus error detection path and a second focus error detection path, the first focus error detection path detects focus errors with a greater sensitivity than the second focus error detection path, while the second focus error detection path detects focus errors over a greater focus error range than the first focus error detection path.

Abstract: Apparatus for optical assessment of a sample includes a radiation source, adapted to generate a beam of coherent radiation, and traveling lens optics, adapted to focus the beam so as to generate first and second spots on a surface of the sample and to scan the spots together over the surface. The distance between the first and second spots is responsive to a pitch of a repetitive pattern of the sample. Collection optics are positioned to collect the radiation scattered from the first and second spots and to focus the collected radiation so as to generate an interference pattern. A detector detects a change in the interference pattern.

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