Method of providing a security document with a security feature, and security document

1. Method of providing a security document with a security feature, said security document comprising a document substrate, said document substrate being a paper substrate, said security document further comprising a security element embedded within said document substrate, said security element comprising an element substrate, said security element further comprising a material sensitive to laser light,

wherein the method further includes the step of directing laser light onto the document substrate so as to alter said material embedded inside the document substrate, such that laser light is directed onto said document substrate where said security element is embedded so as to provide said security element with a detectable marking; and wherein the step of directing laser light onto the document substrate further includes passing laser light through the document substrate where the document substrate covers the security element such that the detectable marking is disposed where the security element is embedded within the document substrate.

2. Method according to claim 1 , wherein the step of directing laser light onto the document substrate is carried out so as to substantially remove at least part of said material, so as to provide said security element with said detectable marking.

3. Method according to claim 2 , wherein the step of directing laser light onto the document substrate is carried out so as to substantially sublimate at least part of said material, so as to provide said security element with said detectable marking.

4. Method according to claim 2 , wherein said material is a conductive material and/or a metallic material.

5. Method according to claim 4 , wherein said material is in the form of metallic particles.

6. Method according to claim 1 , wherein said material sensitive to laser light is present as a layer on the security element.

7. Method according to claim 1 , further including the step of producing perforations in the material after incorporation of said material onto or into said element substrate but prior to embedding the security element in the document substrate.

8. Method according to claim 7 , wherein the step of producing perforations in the material further includes producing perforations in the element substrate.

9. Method according to claim 1 , wherein the security element is a strip or a patch.

10. Method according to claim 1 , wherein the security element comprises a cellulose substrate.

11. Method according to claim 1 , wherein said detectable marking is visible by transmission but not by reflection, and/or wherein said detectable security marking is detectable using magnetic detectors.

12. Method according to claim 1 , wherein said detectable marking is made in register with a feature of the document substrate.

13. Method according to claim 12 , wherein said detectable marking is made in register with a mark printed on the document substrate or a watermark within the document substrate.

14. Method according to claim 12 , wherein said detectable marking is made in register with a mark printed on the document substrate or a watermark within the document substrate, and in register with a side of the document substrate.

15. Method according to claim 12 , wherein said detectable marking is made in register with a side of the document substrate.

16. Method according to claim 1 , wherein said detectable marking is used to customize the security document.

17. Method according to claim 16 , wherein said detectable marking is selected to identify an owner of the security document.

18. Method according to claim 1 , wherein the step of directing laser light onto the document substrate so as to alter said material sensitive to laser light so as to provide said security element with a detectable marking, is carried out without substantially affecting the document substrate.