Multipass multiphoton absorption method and apparatus

Abstract

A method of increasing the efficiency of a multiphoton absorption process and apparatus. The method includes: providing a photoreactive composition; providing a source of sufficient light for simultaneous absorption of at least two photons; exposing the photoreactive composition to at least one transit of light from the light source; and directing at least a portion of the first transit of the light back into the photoreactive composition using at least one optical element, wherein a plurality of photons not absorbed in at least one transit are used to expose the photoreactive composition in a subsequent transit.

1 .- 29 . (canceled)  
   
   
       30 . An apparatus for multiphoton absorption, comprising: 
 a photoreactive composition;    a light source providing sufficient light for simultaneous absorption of at least two photons by the photoreactive composition;    a plurality of optical elements, wherein the photoreactive compositions is located between at least two of the plurality of optical elements, wherein at least one optical element of the plurality of the optical elements is capable of selectively reflecting the light through the photoreactive composition without focusing, and at least one optical element of the plurality of optical elements is capable of selectively focusing the light at a focal point within the photoreactive composition.    
   
   
       31 .- 33 . (canceled)  
   
   
       34 . The apparatus of  claim 30  wherein the light source provides infrared or visible light sufficient for simultaneous absorption of at least two photons by the photoreactive composition.  
   
   
       35 . The apparatus of  claim 30  wherein the photoreactive composition comprises a reactive species.  
   
   
       36 . The apparatus of  claim 35  wherein the reactive species is a curable species.  
   
   
       37 . The apparatus of  claim 30  wherein the photoreactive composition comprises a multiphoton photosensitizer.  
   
   
       38 . The apparatus of  claim 30  wherein the photoreactive composition comprises an electron donor compound.  
   
   
       39 . The apparatus of  claim 30  wherein the photoreactive composition comprises a photoinitiator.  
   
   
       40 . The apparatus of  claim 30  wherein the photoreactive composition comprises about 5% to about 99.79% by weight of the least one reactive species, about 0.01% to about 10% by weight of the at least one multiphoton photosensitizer, up to about 10% by weight of the at least one electron donor compound, and about 0.1% to about 10% by weight of the at least one photoinitiator, based upon the total weight of solids.  
   
   
       41 . The apparatus of  claim 30  wherein the light source is capable of pulse irradiating.  
   
   
       42 . The apparatus of  claim 41  wherein the light source comprises a pulsed laser.  
   
   
       43 . The apparatus of  claim 42  wherein the pulsed laser comprises a near infrared pulsed laser having a pulse length less than about 10 nanoseconds.  
   
   
       44 . An apparatus for multiphoton absorption, comprising: 
 a photoreactive composition;    a light source providing infrared or visible light sufficient for simultaneous absorption of at least two photons by the photoreactive composition;    a plurality of optical elements, wherein the photoreactive composition is located between at least two of the plurality of optical elements, wherein at least one optical element of the plurality of optical elements is capable of selectively reflecting the light through the photoreactive composition without focusing, and at least one optical element of the plurality of optical elements is capable of selectively focusing the light at a focal point within the photoreactive composition for increasing the efficiency of the multiphoton absorption process relative to same process that uses only one transit of light.    
   
   
       45 . An apparatus for multiphoton absorption, comprising: 
 a photoreactive composition;    a light source providing infrared or visible light sufficient for simultaneous absorption of at least two photons by the photoreactive composition;    a plurality of optical elements, wherein the photoreactive composition is located between at least two of the plurality of optical elements, wherein at least two optical elements of the plurality of optical elements are capable of selectively focusing the light at one or more focal points within the photoreactive composition for increasing the efficiency of the multiphoton absorption process relative to same process that uses only one transit of light, and further wherein each of the plurality of optical elements is aligned so the light encounters each of the plurality of optical elements in sequence.    
   
   
       46 . The apparatus of  claim 45  wherein at least one optical element of the plurality of optical elements is capable of selectively reflecting the light through the photoreactive composition without focusing.