Abstract: A light intensity, direct overwrite, magneto-optical system generates signals such that, during the formation of a recording mark on an optical disk, a laser is driven a) at a pedestal power level, then b) at a quench power level for a first quench period t.sub.1, the quench power level being less than the pedestal power level, then c) at a write power level for a write period t.sub.2 whereby the reference bit becomes oriented in the writing direction, the write power level being greater than the pedestal power level, then d) at the quench power level for a second quench period t.sub.3, and then e) at the pedestal power level until the formation of another recording mark begins. The system is provided with a controller to determine optimal lengths of the quench periods t.sub.1 and t.sub.3, thereby reducing thermal interference between closely spaced recording marks. From sample recording marks, recorded with different quench periods t.sub.1 and t.sub.

Abstract: A method and apparatus are provided for determining an adjustable precompensation value in a partial-response maximum-likelihood (PRML) data channel. The PRML data channel includes an adjustable precompensation function for modulating the write data waveform. A predetermined test pattern is written using write circuitry in the disk file. The predetermined test pattern is insensitive to channel misequalization and provides a reference for gain and timing control. The written predetermined test pattern is read back using read circuitry in the disk file. An error in sample values in the read back predetermined test pattern is identified using logic provided in the PRML data channel while performing a standard read operation of a data sector written with the test pattern. The adjustable write precompensation value is adjusted responsive to identifying an error.

Abstract: A high resolution lithographic mask having a desired pattern is generated and used to replicate the pattern onto a film in a one-step process.A film of phase-changeable material in one state is provided on a conductive substrate. By scanning tunneling microscope techniques, the state and thereby the conductivity or other property of the material in selected areas of the film is changed to a second state to provide from the film a mask having a desired pattern defined by crystalline areas. Amorphous material need not be removed from the mask.To replicate the pattern on another film, the latter is placed on another conductive substrate; the mask is positioned with its patterned side within electron tunneling distance of said other film; and the pattern is replicated in a single step by applying a voltage between the mask and other film.