Optical System for Direct Imaging of Light Markable Material

Abstract

An imaging system. An array of light sources and an array of lenses corresponding to the light sources and having optical axes substantially parallel to one another are provided. The lenses produce collimated output beams. An afocal optical relay having an optical axis substantially parallel to the optical axes of the lenses is also included, the array of lenses being positioned relative to the afocal optical relay so as to form an optical system that produces an image of each collimated output beam on an image plane, each image having a prescribed depth of focus and spot size. The light sources preferably are lasers producing an array of respective laser beams having high intensity and a long waist. A system for writing information on a light-sensitive label includes the imaging system. Methods of imaging and of writing information on a light-sensitive label are also provided.

1 . An imaging system, comprising:
 a source array of light sources;   an array of lenses corresponding to the light sources having optical axes substantially parallel to one another, the lenses producing collimated output beams; and   an afocal optical relay having an optical axis substantially parallel to the optical axes of the lenses;   wherein the array of lenses is positioned relative to the afocal optical relay so as to form an optical system that produces an image of each collimated output beam on an image plane, each image having a prescribed depth of focus and minimum spot size.   
     
     
         2 . The imaging system of  claim 1 , wherein each of the light sources has a separately variable output power, and the light sources are modulated so as to selectively vary their respective output powers. 
     
     
         3 . The imaging system of  claim 2 , wherein the light sources are programmable laser diodes that may be individually modulated by varying a current supplied to the diodes. 
     
     
         4 . The imaging system of  claim 3 , wherein the light sources are arranged in a linear array. 
     
     
         5 . The imaging system of  claim 4 , wherein the afocal optical relay comprises a series of powered mirrors. 
     
     
         6 . The imaging system of  claim 5 , wherein the powered mirrors comprise a first, concave mirror, a second, convex mirror, and a third, concave mirror. 
     
     
         7 . The imaging system of  claim 6 , wherein the light sources have a substantially punctile structure in comparison to the center-to-center spacing between the lenses, the collimated beams produced therefrom being magnified by the optical relay such that the images overlap by a selected amount. 
     
     
         8 . The imaging system of  claim 1 , wherein the light sources are laser diodes and the afocal optical relay comprises a series of powered mirrors. 
     
     
         9 . The imaging system of  claim 1 , wherein the light sources have a substantially punctile structure in comparison to the center-to-center spacing between the lenses, the collimated beams produced therefrom being magnified by the afocal optical relay such that the images overlap by a selected amount. 
     
     
         10 . An imaging system, comprising:
 a source array of light sources;   an array of lenses corresponding to the light sources, the lenses having optical axes substantially parallel to one another and being positioned relative to their respective light sources so as to produce first images of the light sources; and   an optical relay comprising at least one powered reflective surface, having an optical axis substantially parallel to the optical axes of the lenses, and being positioned relative to the first images of the light sources to produce at an image plane magnified second images of the light sources, whereby the powered reflective surface serves to minimize power loss in the optical relay.   
     
     
         11 . The imaging system of  claim 10 , wherein each of the light sources has a separately variable output power, and the light sources are modulated so as to selectively vary their separate output powers. 
     
     
         12 . The imaging system of  claim 11 , wherein the light sources are programmable laser diodes that may be individually modulated by varying a current supplied to the diodes. 
     
     
         13 . The imaging system of  claim 12 , wherein the light sources are arranged in a linear array. 
     
     
         14 . The imaging system of  claim 10 , wherein the afocal optical relay comprises a series of powered mirrors that form an afocal system. 
     
     
         15 . The imaging system of  claim 10 , wherein the light sources are lasers. 
     
     
         16 . The imaging system of  claim 15 , wherein the powered mirrors comprise a first, concave mirror, a second, convex mirror, and a third, concave mirror. 
     
     
         17 . The imaging system of  claim 10 , wherein the light sources have a substantially punctile structure in comparison to the center-to-center spacing between the lenses, the first images produced thereby being magnified by the optical relay such that the second images overlap by a selected amount. 
     
     
         18 . The imaging system of  claim 1 , wherein the light sources are lasers. 
     
     
         19 . An imaging system, comprising:
 a source array of lasers, the source array of lasers producing an array of respective laser beams;   an array of lenses corresponding to, and disposed at a selected location relative to, the source array of lasers so as to produce magnified images of the respective laser beams; and   an afocal optical relay, disposed at a selected location relative to the array of lenses, so as to produce, at an image plane, images of the respective laser beams, wherein the images meet a selected blur criterion.   
     
     
         20 . The imaging system of  claim 19 , wherein each lens within the array of lenses has a front focal plane and a back focal plane, and wherein the lasers are disposed at a selected object plane relative to the front focal planes of the respective lenses. 
     
     
         21 . The imaging system of  claim 20 , wherein each laser beam has a waist and wherein the optical relay has an object plane located at a distance with respect to the waist such that adjacent images formed by the optical relay overlap by a selected amount. 
     
     
         22 . The imaging system of  claim 19 , wherein each laser beam has a waist and wherein the optical relay has an object plane located at a distance with respect to the waist such that adjacent images formed by the optical relay overlap by a selected amount. 
     
     
         23 . The imaging system of  claim 22 , wherein the optical relay is an afocal system wherein aberrations in the image are minimized for an objected located at the object plane. 
     
     
         24 . The imaging system of  claim 23 , wherein the lasers are multi-mode lasers. 
     
     
         25 . The imaging system of  claim 22 , wherein each of the lasers has a separately variable output power, and the lasers are modulated so as to selectively vary their separate output powers. 
     
     
         26 . The imaging system of  claim 25 , wherein the lasers are programmable laser diodes that may be individually modulated by varying a current supplied to the diodes. 
     
     
         27 . A method of imaging, comprising:
 providing a plurality of light sources;   collimating light from the light sources so as to produce a corresponding plurality of collimated light beams; and   afocally producing images of the plurality of light beams at an image plane, each image having a prescribed depth of focus and minimum spot size.   
     
     
         28 . The method of  claim 27 , wherein the light sources have a substantially punctile structure, and the collimated light beams therefrom are caused to overlap by a selected amount at the image plane. 
     
     
         29 . The method of  claim 28 , further comprising magnifying the image a fractional amount. 
     
     
         30 . The method of  claim 27 , further comprising modulating the light sources so as to selectively vary their individual power outputs. 
     
     
         31 . The method of  claim 28 , further comprising arranging the light source in a linear array so that a two-dimensional pattern can be produced by modulating the light sources while a target is moved through the light beams in a direction perpendicular to the axis of the linear array. 
     
     
         32 . A method of imaging, comprising:
 providing a plurality of light sources;   collimating light from the light sources so as to produce a corresponding plurality of collimated light beams; and   reflectively producing images of the plurality of light beams at an image plane.   
     
     
         33 . The method of  claim 32 , wherein reflectively producing images comprises causing the plurality of light beams to be reflected sequentially from a plurality of light powered surfaces. 
     
     
         34 . The method of  claim 33 , further comprising magnifying the image. 
     
     
         35 . The method of  claim 32 , further comprising modulating the light sources so as to selectively vary their individual power outputs. 
     
     
         36 . The method of  claim 33 , further comprising arranging the light sources in a linear array so that a two-dimensional pattern can be produced by modulating the light sources while a target is moved through the light beams in a direction perpendicular to the axis of the linear array. 
     
     
         37 . The method of  claim 32 , wherein the light sources are laser light sources. 
     
     
         38 . A method of imaging, comprising:
 providing a plurality of laser light sources having respective outputs;   separately producing a plurality of respective images of the outputs at a selected location; and   afocally producing a single image of the outputs at an image plane, wherein the plurality of outputs at the image plane meet a selected blur criteria.