Optically variable film, apparatus and method for making the same

Abstract

An apparatus for producing an optically variable film includes a laser configured to emit a beam, a telescoping lens section having a first lens and a second lens spaced apart by a first distance and an interferometer configured to direct the beam toward a workpiece. The laser may be operated at a predetermined power level and the first and second lenses are sized and spaced relative to one another to direct the beam onto the workpiece at about 200-230 dots per inch. The workpiece may include a polyethylene terephthalate (PET) layer configured to be ablated by the beam, forming a microstructure in the surface of the layer. The microstructure may be randomized and used to present non-chroma visual effects.

1 - 16 . (canceled) 
     
     
         17 . A polyethylene terephthalate (PET) layer comprising:
 a surface having a microstructure formed therein in response to exposure to a beam emitted from a laser, the microstructure including a randomized section having a plurality of peaks having different heights and valleys having different depths,   wherein the microstructure is configured to present a substantially non-chroma visual effect.   
     
     
         18 . The PET layer of  claim 17 , wherein the microstructure further includes a non-randomized section configured to present a substantially multi-chroma effect. 
     
     
         19 . An optically variable film comprising:
 a base layer having a microstructure imprinted therein; and   a reflective layer extending of the base layer and microstructure and substantially matching a profile of the microstructure,   wherein the microstructure includes a randomized section having a plurality of peaks extending to different heights, valleys extending to different depths, and different slope magnitudes between adjacent peaks and valleys, and   wherein the reflective layer, over the randomized section, produces a substantially non-chroma visual effect.   
     
     
         20 . The optically variable film of  claim 19 , wherein the microstructure further comprising a non-randomized section formed in a predetermined pattern such that the reflective layer, over the non-randomized section, presents a multi-chroma visual effect. 
     
     
         21 . The PET layer of  claim 17 , wherein the PET layer melts in response to exposure to the beam emitted by the laser. 
     
     
         22 . The optically variable film of  claim 19 , wherein the base layer is polyethylene terephthalate. 
     
     
         23 . The optically variable film of  claim 22 , wherein the polyethylene terephthalate layer melts in response to exposure to a beam emitted by the laser.