System, method and article of manufacture for improved laser direct imaging a printed circuit board utilizing a mode locked laser and scophony operation

Abstract

A system, method and article of manufacture is disclosed that provides an improved, higher efficiency, more accurate laser direct imaging on a photosensitive medium on a substrate using a ultraviolet, mode-locked laser having a low average power and a short pulse width. The ultraviolet, mode-locked laser is modulated in a scophony mode. The resulting in-scan edges having improved perpendicularity relative to the underlying substrate. The resulting cross scan beginning and end having improved perpendicularity relative to the underlying substrate. The improved perpendicularity resulting in improved accuracy over the prior art.

What is claimed is:  
     
         1 . A laser direct imaging apparatus for imaging a pixel on a photosensitive medium with a laser beam, the apparatus comprising: 
 a) a substrate held in a frame, said substrate including: 
 (i) a width of between 6 inches and 25 inches and a length of between 6 inches and 36 inches;  
 (ii) a first surface and an opposing second surface;  
 (iii) a first photosensitive layer on said first surface and said second surface; and  
 (iv) a first intermediate layer between said substrate and said first photosensitive layer;  
   b) a UV, mode locked laser operable to emit a pulsed laser beam, said pulsed laser beam including: 
 (i) a wavelength of between 200 nm and 532 nm;  
 (ii) a pulse width of between 1 ps and 20 ps;  
 (iii) a pulse frequency of between 50 MHz and 400 MHz;  
 (iv) an average power of between 0.050 watts and 20 watts; and  
 (v) a duty cycle of between 125 to 1 and 20,000 to 1;  
   c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam to cause an acoustic wave to travel in said crystal at an acoustic speed;  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction at an in-scan scanning speed to substantially expose one or more first pixels of said first photosensitive layer, said first pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein the first side, said first′ side, said first beginning and said first end are substantially perpendicular to said substrate; and    said imaging apparatus provides an optical magnification between the acousto-optical modulator and said photosensitive layer, wherein the in-scan scanning speed is matched to the acoustic speed and any optical magnification to achieve scophony mode scanning.    
     
     
         2 . An apparatus as recited in  claim 1 , wherein said mode locked laser is a solid state laser.  
     
     
         3 . An apparatus as recited in  claim 1 , wherein said first intermediate layer is conductive.  
     
     
         4 . An apparatus as recited in  claim 1 , wherein said frame is fixed and said first scanner unit is movable in at least one cross scan direction.  
     
     
         5 . An apparatus as recited in  claim 1 , further comprising: 
 said substrate further includes: 
 a second photosensitive layer on said second surface; and  
 a second intermediate layer between said substrate and said second photosensitive layer on said second surface;  
   said first scanner unit includes a second scanner unit;    said acousto-optical modulator includes a beam switch; and    said second scanner unit oriented to receive said modulated, pulsed laser beam, said second scanner unit operable to direct and move said modulated, pulsed laser beam across said second photosensitive layer in an in-scan direction at an in-scan scanning speed to substantially expose one or more second pixels of said second photosensitive layer, said second pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction and a second beginning and a second end in said cross scan direction, wherein said second side, said second′ side, said second beginning and said second end are substantially perpendicular to said substrate.    
     
     
         6 . An apparatus as recited in  claim 5 , wherein said frame is fixed and said first scanner unit and said second scanner unit are movable in at least one cross scan direction.  
     
     
         7 . A method for laser direct imaging a pixel on a photosensitive medium with a laser beam, comprising: 
 a) providing a substrate in a frame, said substrate including: 
 (i) a width of between 6 inches and 25 inches and a length of between 6 inches and 36 inches; and  
 (ii) a first surface and an opposing second surface;  
   b) providing a first photosensitive layer on said first surface;    c) providing a first intermediate layer between said substrate and said first photosensitive layer;    d) emitting a UV, mode locked laser beam said laser beam including: 
 (i) a wavelength of between 200 nm and 532 nm;  
 (ii) a pulse width of between 1 ps and 20 ps;  
 (iii) a pulse frequency of between 50 MHz and 400 MHz;  
 (iv) an average power of between 0.050 watts and 20 watts; and  
 (v) a duty cycle of between 125 to 1 and 20,000 to 1;  
   e) receiving said laser beam in an acousto-optical modulator having an acoustic speed;    f) receiving a modulating signal in said acousto-optical modulator;    g) modulating said laser beam in said acousto-optical modulator;    h) receiving said modulated laser beam in a first scanner unit;    i) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction at an in-scan scanning speed to substantially expose one or more first pixels of the first photosensitive layer, said first pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein said first side, said first′ side, said first beginning and said first end are substantially perpendicular to said substrate;    j) providing an optical magnification between the acousto-optical modulator and said photosensitive layer; and    k) matching the in-scan scanning speed to the acoustic speed and any optical magnification to achieve scophony mode scanning.    
     
     
         8 . A method as recited in  claim 7 , wherein said mode locked laser is a solid state laser.  
     
     
         9 . A method as recited in  claim 7 , wherein said first intermediate layer is conductive.  
     
     
         10 . A method as recited in  claim 7 , further comprising, moving said first scanner unit in at least one cross scan direction.  
     
     
         11 . A method as recited in  claim 7 , further comprising: 
 m) providing a second photosensitive layer on said second surface;    n) providing a second intermediate layer between said substrate and said second photosensitive layer on said second surface;    o) wherein receiving said modulated laser beam in said first scanner unit further includes: 
 (i) switching said modulated laser beam; and  
 (ii) emitting alternatively said modulated laser beam to a first scanner unit and a second scanner unit; and  
 (iii) receiving said modulated laser beam in said second scanner unit; and  
   p) directing and moving said modulated laser beam across said second photosensitive layer in an in-scan direction at an in-scan scanning speed to substantially expose one or more second pixels of the second photosensitive layer, said second pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction and a second beginning and a second end in said cross scan direction, wherein said second side, said second′ side, said second beginning and said second end are substantially perpendicular to said substrate.    
     
     
         12 . An method as recited in  claim 11 , further comprising, moving said first scanner unit and said second scanner unit in at least one cross scan direction.  
     
     
         13 . A laser direct imaging apparatus for imaging a pixel on a photosensitive medium with a laser beam, comprising: 
 a) a substrate, said substrate including: 
 (i) a first surface and an opposing second surface;  
 (ii) a first photosensitive layer on said first surface; and  
   b) a mode locked laser operable to emit a pulsed laser beam, said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1;    c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam;  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction to substantially expose one or more first pixels of said first photosensitive layer, said first pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein said first side and said first′ side are substantially perpendicular to said substrate.    
     
     
         14 . An apparatus as recited in  claim 13 , wherein said substrate further includes a width of between 6 inches and 25 inches and a length of between 6 inches and 36 inches.  
     
     
         15 . An apparatus as recited in  claim 13 , wherein said substrate further includes a first intermediate layer between said substrate and said first photosensitive layer.  
     
     
         16 . An apparatus as recited in  claim 15 , wherein said intermediate layer is conductive.  
     
     
         17 . An apparatus as recited in  claim 13 , wherein said mode locked laser is a UV, mode locked laser operable to emit a pulsed laser beam having a wavelength of between 200 nm and 532 nm.  
     
     
         18 . An apparatus as recited in  claim 13 , wherein the pulsing laser beam has a pulse width of between 1 ps and 20 ps.  
     
     
         19 . An apparatus as recited in  claim 13 , wherein the pulsing laser beam has a pulse frequency of between 50 MHz and 400 MHz.  
     
     
         20 . An apparatus as recited in  claim 13 , wherein the pulsing laser beam has an average power of between 0.050 watts and 20 watts.  
     
     
         21 . An apparatus as recited in  claim 13 , wherein the mode locked laser is a solid state laser.  
     
     
         22 . An apparatus as recited in  claim 13 , wherein the substrate is held in a frame.  
     
     
         23 . An apparatus as recited in  claim 22 , wherein said frame is fixed and said first scanner unit is movable in at least one cross scan direction.  
     
     
         24 . An apparatus as recited in  claim 13 , wherein: 
 said modulating signal induces an acoustic wave to travel in said crystal at an acoustic speed; and    said imaging apparatus provides an optical magnification between the acousto-optical modulator and said photosensitive layer, wherein the in-scan scanning speed is matched to the acoustic speed and any optical magnification to achieve scophony mode scanning.    
     
     
         25 . An apparatus as recited in  claim 24 , wherein said first beginning and said first end is substantially perpendicular to said substrate.  
     
     
         26 . An apparatus as recited in  claim 13 , wherein said first scanner unit is operable to scan said mode locked laser beam between 0 inches and 30 inches in said in-scan direction across said first surface.  
     
     
         27 . An apparatus as recited in  claim 13 , wherein said first scanner unit includes a second scanner unit and said acousto-optical modulator includes a beam switch operable to switch said pulsed, modulated laser beam between said first scanner unit and said second scanner unit.  
     
     
         28 . An apparatus as recited in  claim 13 , further comprising: 
 e) said substrate further includes a second photosensitive layer on said second surface;    f) said first scanner unit includes a second scanner unit;    g) said acousto-optical modulator includes a beam switch; and    i) said second scanner unit oriented to receive said modulated, pulsed laser beam, said second scanner unit operable to direct and move said modulated, pulsed laser beam across said second photosensitive layer in an in-scan direction to substantially expose one or more second pixels of said second photosensitive layer, said second pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction and a second beginning and a second end in said cross scan direction, wherein said second side and said second′ side are substantially perpendicular to said substrate.    
     
     
         29 . An apparatus as recited in  claim 28 , wherein said substrate is held in a frame, said frame is fixed and said first scanner unit and said second scanner unit are movable in at least one cross scan direction.  
     
     
         30 . An apparatus as recited in  claim 13 , further comprising: 
 e) said substrate further includes a second photosensitive layer on said second surface;    f) said mode locked laser includes a second mode locked laser;    g) said first scanner unit includes a second scanner unit;    h) said acousto-optical modulator includes a second acousto-optical modulator, said second acousto-optical modulator including: 
 (i) a second crystal oriented to receive a second pulsed laser beam from said second mode locked laser; and  
 (ii) a second transducer, said second transducer in contact with said second crystal, said second transducer operable to receive said modulating signal from said external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam;  
   i) said second scanner unit oriented to receive said modulated, pulsed laser beam, said second scanner unit operable to direct and move said modulated, pulsed laser beam across said second photosensitive layer in an in-scan direction to substantially expose one or more second pixels of said second photosensitive layer, said second pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction and a second beginning and a second end in said cross scan direction, wherein said second side and said second′ side are substantially perpendicular to said substrate.    
     
     
         31 . A method for laser direct imaging a pixel on a photosensitive medium with a laser beam, comprising: 
 a) providing a substrate including a first surface and an opposing second surface;    b) providing a first photosensitive layer on said first surface;    c) emitting a mode locked laser beam, said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1;    d) receiving said laser beam by an acousto-optical modulator;    e) receiving a modulating signal in said acousto-optical modulator;    f) modulating said laser beam in said acousto-optical modulator;    g) receiving said modulated laser beam in said first scanner unit; and    h) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction to substantially expose one or more first pixels of the first photosensitive layer, said first pixel defined by a surface area contacted by said modulated laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein said first side and said first′ side are substantially perpendicular to said substrate.    
     
     
         32 . A method as recited in  claim 31 , wherein said substrate further includes a width of between 6 inches and 25 inches and a length of between 6 inches and 36 inches.  
     
     
         33 . A method as recited in  claim 31 , wherein said substrate further includes a first intermediate layer between said substrate and said first photosensitive layer.  
     
     
         34 . A method as recited in  claim 33 , wherein said intermediate layer is conductive.  
     
     
         35 . A method as recited in  claim 31 , wherein said emitting a mode locked laser beam includes emitting a UV, mode locked laser beam having a wave length of between 200 nm and 532 nm.  
     
     
         36 . A method of  claim 31 , wherein said pulsing laser has a pulse width of between 1 ps and 20 ps.  
     
     
         37 . A method of  claim 31 , wherein said pulsing laser has a pulse frequency of between 50 MHz and 400 MHz.  
     
     
         38 . A method of  claim 31 , wherein said pulsing laser has an average power of between 0.050 watts and 20 watts.  
     
     
         39 . A method of  claim 31 , wherein said mode locked laser is a solid state laser.  
     
     
         40 . A method of  claim 31 , further comprising, securing said substrate in a frame.  
     
     
         41 . A method of  claim 40 , further comprising, moving said first scanner unit in at least one cross scan direction.  
     
     
         42 . A method as recited in  claim 31 , wherein; 
 inducing an acoustic wave to travel in said crystal at an acoustic speed;    providing an optical magnification between said acousto-optical modulator and said photosensitive layer;    directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction at an in-scan scanning speed; and    matching the in-scan scanning speed to the acoustic speed and any optical magnification to achieve scophony mode scanning.    
     
     
         43 . A method as recited in  claim 42 , wherein said first beginning and said first end being substantially perpendicular to said substrate.  
     
     
         44 . A method as recited in  claim 31 , further comprising scanning said mode locked laser beam between 0 inches and 30 inches in said in-scan direction across said first surface.  
     
     
         45 . A method as recited in  claim 31 , further comprising 
 switching said modulated laser beam and alternatively emitting said modulated laser beam to said first scanner unit and a second scanner unit.    
     
     
         46 . A method as recited in  claim 31 , further comprising: 
 i) providing a second photosensitive layer on said second surface;    j) wherein receiving said modulated laser beam in said first scanner unit further includes: 
 (i) switching said modulated laser beam; and  
 (ii) emitting alternatively said modulated laser beam to said first scanner unit and a second scanner unit;  
   k) receiving said modulated laser beam in said second scanner unit; and    l) directing and moving said modulated laser beam across said second photosensitive layer in an in-scan direction to substantially expose a second pixel of the second photosensitive layer, said second pixel defined by a surface area contacted by said modulated laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction and a second beginning and a second end in said cross scan direction, wherein said first side and said first′ side are substantially perpendicular to said substrate.    
     
     
         47 . A method as recited in  claim 31 , further comprising: 
 i) providing a second photosensitive layer on said second surface;    j) wherein emitting a mode-locked laser beam includes emitting a first laser beam and a second laser beam;    k) wherein receiving said laser beam by an acousto-optical modulator includes receiving said first laser beam by a first acousto-optical modulator and receiving said second laser beam by a second acousto-optical modulator;    l) wherein receiving a modulating signal in said acousto-optical modulator includes receiving a modulating signal in said first acousto-optical modulator and said second acousto-optical modulator;    m) wherein modulating said laser beam in said acousto-optical modulator includes modulating said first laser beam in said first acousto-optical modulator and modulating said second laser beam in said second acousto-optical modulator;    n) wherein receiving said modulated laser beam in said first scanner unit includes; receiving said first modulated laser beam in said first scanner unit and receiving said second modulated laser beam in said second scanner unit; and    o) wherein directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction includes: 
 (i) directing and moving said first modulated laser beam across said first photosensitive layer in an in-scan direction to substantially expose one or more first pixels of the first photosensitive layer, said first pixel defined by a surface area contacted by said modulated laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in said cross scan direction, , wherein said first side and said first′ side are substantially perpendicular to said substrate; and  
 (ii) directing and moving said second modulated laser beam across said second photosensitive layer in an in-scan direction to substantially expose one or more second pixels of the second photosensitive layer, said second pixel defined by a surface area contacted by said modulated laser beam and substantially penetrating through said second photosensitive layer, said second pixel having a second side and a second′ side in said in-scan direction, wherein said second side and said second′ side are substantially perpendicular to said substrate.  
   
     
     
         48 . An improved laser direct imaging apparatus for imaging a pixel on a photosensitive medium with a laser beam, the apparatus comprising: 
 a) a substrate, said substrate including: 
 (i) a first surface and an opposing second surface;  
 (ii) a first photosensitive layer on said first surface;  
   b) a mode locked laser operable to emit a pulsed laser beam;    c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam; and  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1, wherein one or more first pixels are substantially exposed, said first pixel having a first side and a first′ side in said in-scan direction, wherein the accuracy of said first side and said first′ side are improved by having improved perpendicularity to said substrate.    
     
     
         49 . An improved laser direct imaging method for imaging a pixel on a photosensitive medium with a laser beam, the method comprising: 
 a) providing a substrate including a first surface and an opposing second surface;    b) providing a first photosensitive layer on said first surface;    c) emitting a mode locked laser beam;    d) receiving said laser beam by an acousto-optical modulator;    e) receiving a modulating signal in said acousto-optical modulator;    f) modulating said laser beam in said acousto-optical modulator;    g) receiving said modulated laser beam in said first scanner unit; and    h) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    providing said mode locked laser with a duty cycle of between 125 to 1 and 20,000 to 1, exposing one or more first pixels, said first pixel having a first side and a first′ side in said in-scan direction, wherein the accuracy of said first side and said first′ side are improved by having improved perpendicularity to said substrate.    
     
     
         50 . A laser direct imaging apparatus providing improved efficiency of imaging a pixel on a photosensitive medium with a laser beam, comprising: 
 a) a substrate, said substrate including: 
 (i) a first surface and an opposing second surface;  
 (ii) a first photosensitive layer on said first surface; and  
   b) a mode locked laser operable to emit a pulsed laser beam;    c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam; and  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1, wherein one or more first pixels are substantially exposed, said first pixel having a first side and a first″ side in said in-scan direction, wherein said first side and said first″ side have improved perpendicularity and efficiency of exposing said pixel is improved by a factor of at least 2.5.    
     
     
         51 . A method of improved efficiency of exposing a pixel on a photosensitive medium with a laser beam, the method comprising: 
 a) providing a substrate including a first surface and an opposing second surface;    b) providing a first photosensitive layer on said first surface;    c) emitting a mode locked laser beam;    d) receiving said laser beam by an acousto-optical modulator;    e) receiving a modulating signal in said acousto-optical modulator;    f) modulating said laser beam in said acousto-optical modulator;    g) receiving said modulated laser beam in said first scanner unit; and    h) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    providing said mode locked laser with a duty cycle of between 125 to 1 and 20,000 to 1, exposing one or more first pixels, said first pixel having a first side and a first″ side in said in-scan direction, wherein said first side and said first″ side have improved perpendicularity to said substrate and efficiency of exposing said pixel is improved by a factor of at least 2.5.    
     
     
         52 . A laser direct imaging apparatus providing improved efficiency of imaging a pixel on a photosensitive medium with a laser beam, comprising: 
 a) a substrate, said substrate including: 
 (i) a first surface and an opposing second surface;  
 (ii) a first photosensitive layer on said first surface; and  
   b) a mode locked laser operable to emit a pulsed laser beam;    c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam; and  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1, wherein one or more first pixels are substantially exposed, and efficiency of exposing said pixel is improved by a factor of at least 2.5.    
     
     
         53 . A method of improved efficiency of exposing a pixel on a photosensitive medium with a laser beam, the method comprising: 
 a) providing a substrate including a first surface and an opposing second surface;    b) providing a first photosensitive layer on said first surface;    c) emitting a mode locked laser beam;    d) receiving said laser beam by an acousto-optical modulator;    e) receiving a modulating signal in said acousto-optical modulator;    f) modulating said laser beam in said acousto-optical modulator;    g) receiving said modulated laser beam in said first scanner unit; and    h) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction;    wherein the improvement comprises:    providing said mode locked laser with a duty cycle of between 125 to 1 and 20,000 to 1, exposing one or more first pixels, and efficiency of exposing said pixel is improved by a factor of at least 2.5.    
     
     
         54 . An apparatus for producing a printed circuit board by laser direct imaging a pixel on the printed circuit board, comprising; 
 a) a substrate, said substrate including: 
 (i) a first surface and an opposing second surface;  
 (ii) a first photosensitive layer on said first surface; and  
 (iii) a first intermediate layer between said first photosensitive layer and said substrate;  
   b) a mode locked laser operable to emit a pulsed laser beam, said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1;    c) an acousto-optical modulator including: 
 (i) a crystal oriented to receive said pulsed laser beam; and  
 (ii) a transducer, said transducer in contact with said crystal, said transducer operable to receive a modulating signal from an external source and to emit said modulating signal into said crystal to modulate said pulsed laser beam;  
   d) a first scanner unit oriented to receive said modulated, pulsed laser beam, said first scanner unit operable to direct and move said modulated, pulsed laser beam across said first photosensitive layer in an in-scan direction to substantially expose one or more first pixels of said first photosensitive layer, said first pixel defined by a surface area contacted by said modulated, pulsed laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first″ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein said first side and said first′ side are substantially perpendicular to said substrate.    
     
     
         55 . A method for producing a printed circuit board by laser direct imaging a pixel on the printed circuit board, comprising: 
 a) providing a substrate including a first surface and an opposing second surface;    b) providing a first photosensitive layer on said first surface;    c) providing a first intermediate layer between said first photosensitive layer and said substrate;    d) emitting a mode locked laser beam, said mode locked laser having a duty cycle of between 125 to 1 and 20,000 to 1;    e) receiving said laser beam by an acousto-optical modulator;    f) receiving a modulating signal in said acousto-optical modulator;    g) modulating said laser beam in said acousto-optical modulator;    h) receiving said modulated laser beam in a first scanner unit; and    i) directing and moving said modulated laser beam across said first photosensitive layer in an in-scan direction to substantially expose one or more first pixels of the first photosensitive layer, said first pixel defined by a surface area contacted by said modulated laser beam and substantially penetrating through said first photosensitive layer, said first pixel having a first side and a first′ side in said in-scan direction and a first beginning and a first end in a cross scan direction, wherein said first side and said first′ side is substantially perpendicular to said substrate.