System and method for multi-beam scanning

Abstract

System and method of photoaltering a material. The system includes a laser source operable to produce a primary pulsed beam, a holographic optical element configured to receive the primary pulsed beam and transmit a plurality of secondary beams, and a scanner operable to direct the secondary beams to the material. The secondary beams are based on the primary pulsed beam. The method includes phase shifting a pulsed laser beam to produce an input beam, holographically altering the input beam to produce a plurality of transmission beams, and scanning a portion of the material with the transmission beams.

1 . A system for photoaltering a material, the system comprising:
 a laser source operable to produce a primary pulsed beam;   a holographic optical element configured to receive the primary pulsed beam and transmit a plurality of secondary beams, the plurality of secondary beams based on the primary pulsed beam; and   a scanner operable to direct the plurality of secondary beams to the material.   
     
     
         2 . The system of  claim 1 , wherein the primary pulsed beam has a first intensity, wherein the holographic optical element is further configured to transmit a first secondary beam and a second secondary beam, the first secondary beam having a second intensity, the second secondary beam having a third intensity, and wherein a sum of the second and third intensities is greater than about 80% of the first intensity. 
     
     
         3 . The system of  claim 1 , wherein the primary pulsed beam has a first intensity, wherein the holographic optical element is further configured to transmit a first secondary beam and a second secondary beam, the first secondary beam having a second intensity, the second secondary beam having a third intensity, and wherein a difference between the second intensity and the third intensity is less than about 5% of an average of the second and third intensities. 
     
     
         4 . The system of  claim 1 , wherein the holographic optical element comprises:
 a first phase grating having a first surface and a second surface, the second surface of the first phase grating opposing the first surface of the first phase grating, the first surface of the first phase grating configured to receive the primary pulsed beam; and   a second phase grating having a first surface and a second surface, the second surface of the second phase grating opposing the first surface of the second phase grating, the first surface of the second phase grating adjacent to the second surface of the first phase grating, the second surface of the second phase grating configured to:
 transmit about 100% of the plurality of secondary beams when the first phase grating and the second phase grating are in a first alignment; 
 transmit about 0% of the plurality of secondary beams when the first phase grating and the second phase grating are in a second alignment; and 
 transmit a variable portion of each of the plurality of secondary beams when the first phase grating and the second phase grating are between the first alignment and the second alignment. 
   
     
     
         5 . The system of  claim 1 , wherein the holographic optical element is further configured to vary a spatial separation between each of the plurality of secondary beams. 
     
     
         6 . The system of  claim 5 , wherein the holographic optical element has a transmission plane and an axis within the transmission plane, and wherein the holographic optical element is configured to pivot the transmission plane about the axis. 
     
     
         7 . The system of  claim 1 , wherein the system has an optical axis extending between the holographic optical element and the material, and wherein the holographic optical element is further configured to rotate about the optical axis. 
     
     
         8 . A system for photoaltering a material, the system comprising:
 a laser source operable to produce a primary pulsed beam;   a first optical element configured to receive the primary pulsed beam and transmit a first secondary beam, the first secondary beam based on the primary pulsed beam and phase shifted from the primary pulsed beam by about a first quarter wavelength;   a first polarizing beam splitter configured to reflect a first polarized beam and transmit a second polarized beam, the first and second polarized beams together based on the first secondary beam;   a subsystem configured to produce a first transmission beam and a second transmission beam based on the first and second polarized beams, the first transmission beam angularly separated from the second transmission beam; and   a scanner operable to direct the first and second transmission beams to the material.   
     
     
         9 . The system of  claim 8 , wherein the subsystem comprises:
 a second optical element configured to receive the first polarized beam and transmit a second secondary beam, the second secondary beam based on the first polarized beam and phase shifted from the first polarized beam by about a second quarter wavelength;   a first mirror configured to reflect the second secondary beam to the second wave plate, the second wave plate further configured to transmit the first transmission beam;   a third optical element configured to receive the second polarized beam and transmit a third secondary beam, the third secondary beam based on the second polarized beam and phase shifted from the second polarized beam by about a third quarter wavelength; and   a second mirror configured to reflect the third secondary beam to the third wave plate, the third wave plate further configured to transmit the second transmission beam.   
     
     
         10 . The system of  claim 9 , wherein each of the first, second, and third optical elements comprises a quarter wave plate. 
     
     
         11 . The system of  claim 9 , wherein the second mirror has an optical plane and is further configured to pivot the optical plane to angularly separate the first transmission beam from the second transmission beam. 
     
     
         12 . The system of  claim 9 , wherein the first polarizing beam splitter is further configured to transmit the first transmission beam from the second wave plate and reflect the second transmission beam from the third wave plate. 
     
     
         13 . The system of  claim 8 , wherein the subsystem comprises:
 a first mirror configured to reflect the first polarized beam;   a second mirror configured to reflect the second polarized beam; and   a second polarizing beam splitter configured to:
 receive the first polarized beam from the first mirror and the second polarized beam from the second mirror; 
 transmit the first polarized beam to the scanner, the first polarized beam being the first transmission beam; and 
 reflect the second polarized beam to the scanner, the second polarized beam being the second transmission beam. 
   
     
     
         14 . The system of  claim 13 , wherein the first mirror has an optical plane and is further configured to pivot the optical plane to angularly separate the first transmission beam from the second transmission beam. 
     
     
         15 . A system for photoaltering a material, the system comprising:
 a laser source operable to produce a primary pulsed beam;   an optical element having a reflectivity less than about 100%, the optical element configured to:
 receive the primary pulsed beam; 
 reflect a first transmission beam; and 
 transmit a secondary beam, the first transmission beam and the secondary beam together based on the primary pulsed beam; 
   a mirror oriented non-parallel to the optical element, the mirror configured to reflect the secondary beam to the optical element, the optical element further configured to transmit a second transmission based on the secondary beam; and   a scanner operable to direct the first and second transmission beams to the material.   
     
     
         16 . The system of  claim 15 , wherein the reflectivity, R, of the optical element is about 0.382. 
     
     
         17 . The system of  claim 15 , wherein the pulsed laser beam has a pulse width of between about 300 picoseconds and about 10 femtoseconds. 
     
     
         18 . The system of  claim 15 , wherein the pulsed laser beam has a wavelength between about 400 nm to about 3000 nm. 
     
     
         19 . The system of  claim 15 , wherein the pulsed laser beam has a pulse energy less than or equal to about 800 nanojoules/pulse. 
     
     
         20 . The system of  claim 15 , wherein the pulsed laser beam has a pulse frequency selected from a range of about 30 MHz to about 1 GHz. 
     
     
         21 . The system of  claim 15 , wherein the pulsed laser beam has a pulse width between about 300 picoseconds and about 10 femtoseconds. 
     
     
         22 . A system for photoaltering a material, the system comprising:
 a laser source operable to produce a primary pulsed beam;   an optical element configured to receive the primary pulsed beam and transmit a phase shifted beam, the phase shifted beam orthogonally polarized with the primary pulsed beam;   a first Wollaston prism configured to:
 receive the phase shifted beam; and 
 transmit a first secondary beam and a second secondary beam, the first and second secondary beams together based on the phase shifted beam, the first secondary beam angularly separated from the second secondary beam; and 
   a scanner operable to direct a first transmission beam and a second transmission beam to the material, the first and second transmission beams based on the first and second secondary beams.   
     
     
         23 . The system of  claim 22 , wherein the first transmission beam is the first secondary beam, and wherein the second transmission beam is the second secondary beam. 
     
     
         24 . The system of  claim 22 , wherein the first transmission beam comprises a third secondary beam and a fourth secondary beam, wherein the second transmission beam comprises a fifth secondary beam and a sixth secondary beam, and wherein the system further comprises a second Wollaston prism coupled to the first Wollaston prism, the second Wollaston prism configured to:
 receive the first and second secondary beams; and   transmit a third secondary beam, a fourth secondary beam, a fifth secondary beam, and a sixth secondary beam, the third and fourth secondary beams together based on the first secondary beam, the fifth and sixth secondary beams together based on the second secondary beam.   
     
     
         25 . A method of photoaltering a material, the method comprising the steps of:
 holographically altering an input beam to produce a plurality of transmission beams; and   scanning a portion of the material with the plurality of transmission beams.   
     
     
         26 . The method of  claim 25 , wherein the scanning step comprises scanning a portion of a cornea with the plurality of transmission beams. 
     
     
         27 . The method of  claim 26 , wherein the scanning step comprises scanning a portion of a cornea at a predetermined depth with the plurality of transmission beams.