Engineering topics
Publications and source records attributed to Guisinger, J. E..
High coercive-force films have reduced sensitivity to wall-domain motion and can record at higher spatial frequencies. Tracks switched in high coercive-force films have track widths independent of applied magnetic field. Upper spatial frequency limit recorded by Curie-point switching in alternating field is greater.
Method uses basic circuit to examine quality and trap density of film used in insulated gate field effect transistors. Data are measured as function of performance and life expectancy.
Manganese bismuth films having improved characteristics for recording information in analogue form, can be produced by a vacuum deposition of Bi and Mn with an atomic ratio of Mn to Bi between 2 and 3.5 or 1.4 and 1.6, followed by a specialized heat treatment which includes very brief exposure to a temperature between about 275 deg and 300 C. Similar MnBi films can be produced more reliably and reproducibly if the initial Bi layer is annealed prior to deposition of the Mn layer. Such an annealing step renders most other factors of the processing relatively non-critical. Deposition of both initial layers is preferably carried out in a vacuum approaching 10 to the -8th power Torr.
A system is developed for maintaining the intensity of a laser beam at a constant level in a thermomagnetic recording and magneto-optic playback system in which an isotropic film is heated along a continuous path by the laser beam for recording. As each successive area of the path is heated locally to the vicinity of its Curie point in the presence of a controlled magnetic field, a magneto-optic density is produced proportional to the amplitude of the controlled magnetic field. To play back the recorded signal, the intensity of the laser beam is reduced and a Faraday or Kerr effect analyzer is used, with a photodetector, as a transducer for producing an output signal.
The results of laser recording experiments in which a magnetic field controls the magnetization distribution along Curie-point switched micron-wide tracks are described. These experiments showed that analog as well as digital information may be recorded in this manner.
In a magneto-optic readout system, a polarized beam of light from a laser is subjected to the magneto-optical effect of a magnetic record medium, and then passed through an analyzer which resolves the beam into two orthogonal vector components so oriented that the two components are of equal amplitude when the angle of rotation due to the magneto-optic effect is zero. Separate photodetectors produce two output signals which are proportional to the amplitudes of the vector components. The two output signals are combined in a differential amplifier through separate logarithmic transfer circuits to produce an output signal proportional to the ratio of the two original detector signals.
Another variation in the preparation of MnBi films from double layers of the constituents is reported. The dependence of Faraday and Kerr rotations on both composition and film thickness in these films suggests a model wherein a reacted double layer is made up of four separate layers. The variance in magneto-optic constants of MnBi reported here and previously is resolved in terms of this model.
A magnetic recording and magneto-optic playback system is disclosed wherein thermomagnetic recording is employed. A transparent isotropic film is heated along a continuous path by a focused laser beam. As each successive area of the path is heated locally to the vicinity of its Curie point in the presence of an applied magnetic field, a magneto-optic density is established proportional to the magnetic field and fixed in place as the area cools once the laser beam moves on to an adjacent area. To play back the recorded data, the intensity of the laser beam is reduced to avoid reaching the vicinity of the Curie point of the film as it is scanned by the laser beam in the same manner as for recording. A Faraday effect analyzer and photo detector are employed as a transducer for producing an output signal.
Narrow Curie point switching transfer in Mn-Bi films by controlling magnetization direction within preselected areas
Starting circuit design for initiating and maintaining arcs in vapor lamps
A current from a sustaining power supply flows through the mercury vapor lamp and, as there are no resistors in series with this supply, the power is efficiently used. This high voltage igniting device protects the transistorized high current, low voltage power supply.