METHOD FOR AUTHENTICATING UV ABSORBING SECURITY MARK

1 . A method of authenticating a document comprising:

providing a document having a substrate comprising an optical brightener;

printing a background with a ultraviolet (UV) absorbing material on the substrate comprising a first pattern of lines having a first frequency and a first orientation;

printing a security mark with the UV material on the substrate comprising a second pattern of lines having a second frequency or a second orientation or both;

placing a lenticular lens over the security mark and background;

illuminating the security mark and background through the lenticular lens with UV light;

orienting the lenticular lens to match either the first orientation or the second orientation; and

authenticating the document if the security mark matches a predetermined security mark.

2 . The method of claim 1 wherein the predetermined security mark is selected from a group consisting of an image, a logo, a series of numbers or letters or both, a bar code, or a hash tag.

3 . The method of claim 1 wherein the first orientation differs from the second orientation by at least 10 degrees.

4 . The method of claim 1 wherein the orientation of the lenticular lens differs from either the first orientation or the second orientation by less than 5 degrees.

5 . The method of claim 1 wherein the first frequency is equal to the second frequency.

6 . The method of claim 1 wherein the first orientation is equal to the second orientation and the first and second frequencies are different.

7 . The method of claim 1 wherein the frequency of the lenticular lens is a multiple of the first or second frequency.

8 . The method of claim 1 wherein the frequency of the lenticular lens is equal to the first or second frequency.

9 . The method of claim 1 wherein the authentication is a visual match with a predetermined security mark.

10 . A method of authenticating a document comprising:

providing a document having a substrate comprising optical brightener;

printing a background with a ultraviolet (UV) absorbing material on the substrate comprising a first pattern of lines having a first frequency and a first orientation;

printing a security mark with the ultraviolet (UV) material on the substrate comprising a second pattern of lines having a second frequency or a second orientation or both;

illuminating the security mark and background with UV light;

capturing an image of the security mark and background with an image capture device;

applying an image transformation algorithm to the captured image;

displaying the transformed image on the display of the image capture device; and

authenticating the document if the security mark matches a predetermined security mark.