Abstract: A non-invasive servo-write system for use in a data recording disk drive. The system measures actuator position and generates a reference clock using semiconductor lasers. Internal position references are provided by reflective diffraction gratings affixed to the actuator arm and the spindle hub. Wavefront reconstruction optics correct for aberrations in the gratings. Optical sensors detect differential changes in the diffraction patterns created by the gratings, eliminating sensitivity to frequency drift. Decode electronics convert optical sensor data into an actuator position measurement. Control electronics drive the voice coil motor within the disk drive, which positions the write transducer to record servo information provided in a servo pattern generator. Transparent windows in the head-disk-assembly cover allow the servo-writer to write drives which are completely assembled and sealed.

Abstract: An optical storage system has an information containing film of a material which has a crystallization temperature between 100.degree. C. and 400.degree. C. and can be switched between the amorphous and the crystalline states. Both the amorphous and crystalline states are substantially a single phase where the stoichiometric ratio of the material remains unchanged. Spots on the film is heated with a circular laser beam with a controlled pulse duration and intensity to melt the material in the spots. The spots are quenched at one rate to produce the amorphous state, and in a second revolution of the disk, at a different rate to produce the crystalline state.

Abstract: A method for improving the memory effect and brightness of an alternating current (AC) excited thin film electroluminensence (ACTEL) device is described. A typical ACTEL device has a thin luminescent layer made of ZnS thin film doped with Mn which is sandwiched between two dielectric layers. ACTEL devices exhibit a brightness versus voltage amplitude hysteresis loop which is commonly referred to as the memory effect. The application of a hybrid AC excitation waveform to the ACTEL device provides increased brightness and improved memory effect stability. The hybrid waveform has an initial portion that is sufficiently high for efficient carrier generation and a remaining waveform portion that is at a lower level than the initial portion for charge collection and holding purposes.