DEVICE AND METHOD FOR MAINTAINING OPTICAL ENERGY DENSITY ON A STORAGE MEDIUM

• US 20080101198A1
• Filed: 10/31/2006
• Published: 05/01/2008
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Wu, Kuohua (Angus), Van Brocklin, Andrew L.
• Granted Patent: US 7,889,220 B2
• Time in Patent Office: Days
• US Class Current: 369/112.01
• CPC Class Codes: G11B 23/40 Identifying or analogous means applied to or incorporated in the record carrier and not intended for visual display simultaneously with the playing-back of the record carrier, e.g. label, leader, photograph

Abstract

A system and method are provided for maintaining optical energy density on a marking area of a storage medium. The method includes the operation of directing a light beam from a light source to an optical system. The light beam can pass through at least one optical component in the optical system, where the optical system has astigmatic properties selected so as to maintain an irradiance within a defined area on the marking area of the storage medium through a range of working distances between the optical system and the marking surface. A further operation is guiding the light beam by the optical system onto the marking area of the storage medium.

Claims

1. A method of maintaining optical energy density on a marking area of a storage medium, comprising:

directing a light beam from a light source to an optical system

passing the light beam through at least one optical component in the optical system, where the optical system having astigmatic properties selected so as to maintain an irradiance within a defined area on the marking area of the storage medium through a range of working distances between the optical system and the marking surface; and

guiding the light beam by the optical system onto the marking area of the storage medium.

2. A method as in claim 1, further comprising the step of providing at least two focal axes using the astigmatic properties of the optical system.

3. A method as in claim 1, further comprising the step of using the astigmatism properties of the optical system to maintain a high enough level of irradiance so as to change a radiation sensitive material on the marking area of the storage medium through the range of working distance between the optical system and the marking surface.

4. A method as in claim 1, further comprising the step of increasing an existing amount of astigmatism in the optical system.

5. A method as in claim 1, further comprising the step of reducing an existing amount of astigmatism in the optical system.

6. A method as in claim 1, further comprising the step of using a first lens in the optical system to adjust astigmatism in a first axis and a second lens in the optical system to adjust astigmatism in a second axis.

7. A method as in claim 1, further comprising the step of using a collimating lens and cylinder lens in order to modify the astigmatic properties of the optical system.

8. A method as in claim 1, wherein the optical system includes at least two optical components that are each fixed relative to the other.

9. A method as in claim 1, wherein the optical system includes an objective lens that is fixed to at least one degree of freedom.

10. A method of claim 1, further comprising the step of forming astigmatic oval spots on the marking area of the storage medium, where each oval spot having separate major axes.

11. A method as in claim 10, further comprising the step of orienting the astigmatic oval spots at approximately 45 degrees to a direction of travel for the storage medium.

12. A device for maintaining optical energy density on a marking area of a storage medium, comprising:

a light source configured to emit a light beam from the light source to an optical system;

an optical system configured to guide the light beam onto the marking area of the storage medium;

where the optical system comprises at least one optical component in the optical system through which the light beam is passed; and

where the at least optical component having astigmatic properties so as to maintain an optical energy density on the marking area of the storage medium through a range of working distances between the optical system and the marking surface.

13. A device as in claim 12, further comprising a fixed objective lens configured to guide the light beam onto the marking area of the storage medium as the light beam is received from the at least one optical at least one component.

14. A device as in claim 12, wherein the at least one optical component comprises a first cylinder lens to adjust astigmatism of the optical system in a first axis and a second cylinder lens to adjust astigmatism in a second axis.

15. A device as in claim 12, wherein the at least one optical component further comprises:

a collimating lens; and

a cylinder lens acting with the collimating lens in order to modify astigmatism of the optical system.

16. A device as in claim 12, wherein the at least one optical component further comprises a bi-aspheric lens used in combination with the objective lens.

17. A device as in claim 12, wherein the at least one optical component further comprises a toric lens and an aspheric lens.

18. A device as in claim 12, wherein the at least one optical component further comprises a collimating lens and a bi-aspheric lens.

19. A device as in claim 13, wherein the light source and the objective lens are fixed with respect to the storage medium.

20. A method of maintaining optical energy density on a marking area of an optical disk, comprising:

directing a light beam from a light source to an optical system;

passing the light beam from the light source through an optical component in an optical system having suitable astigmatic properties so as to maintain an irradiance within a track on the optical disk having a variable working distance between the optical system and the optical disk; and

guiding the light beam by the optical system onto a track of the optical disk using a objective lens fixed with respect to the optical system.