Imaging system for thermal transfer

Abstract

An optical imaging system is disclosed for selective thermal transfer of a material from a donor film to a substrate. The imaging system includes a light source assembly that is configured to emit a patterned light beam. The patterned light beam includes a plurality of discrete output light segments where the segments at most partially overlap. The imaging system further includes a light relay assembly that receives and projects the plurality of discrete output light segments onto a transfer plane so as to form a projected light segment by a substantial superposition of the plurality of discrete output light segments. When a donor film that includes a transferable material is placed proximate a substrate that lies in the transfer plane, the projected light segment is capable of inducing a transfer of the transferable material onto the substrate.

1 . An optical imaging system for selective thermal transfer of a material from a donor film to a substrate, the optical imaging system comprising: 
 a light source assembly comprising at least one light source coupled to at least one optical fiber, the light source assembly emitting a patterned light beam that includes a plurality of emitted light segments, the plurality of emitted light segments at most partially overlapping, each emitted light segment having: 
 a first full divergence angle and a first uniformity along a first direction; and  
 a second full divergence angle and a second uniformity along a second direction;  
   a light homogenizer receiving and homogenizing each emitted light segment and transmitting a corresponding homogenized light segment, each transmitted homogenized light segment having: 
 a third full divergence angle and a third uniformity along the first direction; and  
 a fourth full divergence angle and a fourth uniformity along the second direction,  
 the third uniformity of each transmitted homogenized light segment being greater than the first uniformity of each corresponding emitted light segment;  
   a mask receiving each of the transmitted homogenized light segments and patterning each transmitted homogenized light segment into a row of n discrete light subsegments along the first direction, n being greater than or equal to one, each discrete light subsegment having a length along the first direction and a height along the second direction, the mask being capable of setting the length of each discrete light subsegment at any value in a range from about 50 microns to about 150 microns with an accuracy of one micron or better; and    a first lens system projecting each row of n discrete light subsegments onto a substrate and forming a single row of n discrete projected light segments thereon, such that when a donor film that includes a transferable material disposed proximate a carrier is placed proximate the substrate between the first lens system and the substrate, each of the n discrete projected light segments induces a transfer of the transferable material from the carrier onto the substrate.    
   
   
       2 . The optical imaging system of  claim 1 , wherein the at least one light source comprises a laser.  
   
   
       3 . The optical imaging system of  claim 1 , wherein the first direction is substantially perpendicular to the second direction.  
   
   
       4 . The optical imaging system of  claim 1 , wherein the second full divergence angle of each emitted light segment is close to zero.  
   
   
       5 . The optical imaging system of  claim 1 , wherein the light homogenizer homogenizes each emitted light segment along the first direction, but not along the second direction.  
   
   
       6 . The optical imaging system of  claim 1 , wherein the fourth full divergence angle of each transmitted homogenized light segment is substantially equal to the second full divergence angle of each emitted light segment.  
   
   
       7 . The optical imaging system of  claim 1 , wherein the third uniformity of each transmitted homogenized light segment is greater than the first uniformity of each corresponding emitted light segment by at least a factor of ten.  
   
   
       8 . The optical imaging system of  claim 1 , wherein the mask includes a plurality of optically transmissive parts, each part being centered on an axis, each axis of each part being along the second direction.  
   
   
       9 . The optical imaging system of  claim 8 , each part having a length along the first direction and a height along the second direction, wherein for at least one part: the length of the part at a location along the height of the part is different than the length of the part at a different location along the height of the part.  
   
   
       10 . The optical imaging system of  claim 1 , wherein the first lens system is anamorphic.  
   
   
       11 . The optical imaging system of  claim 1 , wherein the first lens system images the mask onto the donor film along the first direction, but not along the second direction.  
   
   
       12 . The optical imaging system of  claim 1 , wherein n is greater than twenty.  
   
   
       13 . The optical imaging system of  claim 12 , wherein the n discrete projected light segments are equally spaced apart.  
   
   
       14 . The optical imaging system of  claim 12 , wherein the distance between the first and the nth discrete projected light segments is at least ten millimeters.  
   
   
       15 . The optical imaging system of  claim 1 , wherein at least one discrete projected light segment has a substantially uniform intensity profile along the first direction and a substantially Gaussian profile along the second direction.  
   
   
       16 . The optical imaging system of  claim 1 , wherein at least one discrete projected light segment has a substantially uniform intensity profile along the first and second directions.  
   
   
       17 . An OLED display system constructed using the optical imaging system of  claim 1 .  
   
   
       18 . The optical imaging system of  claim 1 , wherein the first lens system projects each row of n discrete light subsegments onto the substrate with a projection magnification of one along the first direction.  
   
   
       19 . The optical imaging system of  claim 1  further comprising a cooling mechanism for cooling the mask.  
   
   
       20 . The optical imaging system of  claim 1 , wherein at least a portion of the optical imaging system is in an inert environment.