Compensating the effects of static head-media spacing variations and nonlinear transition shift in heat assisted magnetic recording
An apparatus comprises a storage medium, a recording head, a source of electromagnetic radiation, and a control circuit for modulating the source of electromagnetic radiation in response to a static deviation of a spacing between the recording head and the storage medium. A method of compensating a static deviation of a spacing between a recording head and a storage medium performed by the apparatus, and a method of precompensating for nonlinear transition shifts in a heat assisted magnetic recording system, are also provided.
1. A method of compensating a nonlinear transition shift in a heat assisted magnetic storage system, the method comprising:
producing a control signal representative of nonlinear transition shift;
modulating a source of electromagnetic radiation to heat a portion of the storage medium in response to the control signal; and
applying a magnetic field to the storage medium to cause magnetic transitions in the storage medium, wherein transition locations in the storage medium are changed by changing a temperature profile in the storage medium.
2. The method of claim 1 , wherein a look-up table is used to map nonlinear transition shift to a power of the source of electromagnetic radiation.
3. The method of claim 1 , wherein a first look-up table is used to map a data pattern to a nonlinear transition shift, and a second look-up table is used to map the nonlinear transition shift to a power of the source of electromagnetic radiation.
4. The method of claim 1 , wherein the source of electromagnetic radiation is controlled to vary a temperature in a storage medium over a range of ±50° K.
5. The method of claim 1 , wherein the source of electromagnetic radiation is modulated within a bit duration length.
6. An apparatus comprising:
a storage medium;
a source of electromagnetic radiation for heating a portion of the storage medium;
a recording head for applying a magnetic field to the storage medium to cause magnetic transitions in the storage medium, wherein transition locations in the storage medium are changed by changing a temperature profile in the storage medium; and
a control circuit for producing a control signal representative of nonlinear transition shift and modulating the source of electromagnetic radiation in response to the control signal.
7. The apparatus of claim 6 , wherein a look-up table is used to map nonlinear transition shift to a power of the source of electromagnetic radiation.
8. The apparatus of claim 6 , wherein a first look-up table is used to map a data pattern to a nonlinear transition shift, and a second look-up table is used to map the nonlinear transition shift to a power of the source of electromagnetic radiation.
9. The apparatus of claim 6 , wherein the source of electromagnetic radiation is controlled to vary a temperature in a storage medium over a range of ±50° K.
10. The apparatus of claim 6 , wherein the source of electromagnetic radiation is modulated within a bit duration length.