Phase-modified quasi-non-diffracting laser beams for high angle laser processing of transparent workpieces

A method for processing a transparent workpiece, the method comprising:

• directing a laser beam oriented along a beam pathway from free space into an impingement surface of the transparent workpiece at an impingement location, wherein:
• the impingement surface is an air-workpiece interface;
• the impingement surface comprises a non-planar topography;
• the laser beam in free space comprises an oblong angular spectrum comprising an axis of symmetry extending from a first axis end having a first radius of curvature to a second axis end having a second radius of curvature, where the first radius of curvature and the second radius of curvature are different such that the oblong angular spectrum is non-axisymmetric about an optical axis of the laser beam;
• and
• a portion of the laser beam directed into the transparent workpiece comprises a laser beam focal line and generates an induced absorption to produce a defect within the transparent workpiece, the laser beam focal line comprising:
• a wavelength λ;
• a spot size wo;
• a Rayleigh range ZR that is greater than
• F
• D
• ⁢
• π
• ⁢
• w
• o
• 2
• λ
• ,
• where FD is a dimensionless divergence factor comprising a value of 10 or greater;
• and
• an internal focal line angle of greater than 10° relative to a plane orthogonal to the impingement surface at the impingement location, such that the defect comprises a defect angle within the transparent workpiece of greater than 10° relative to a plane orthogonal to the impingement surface at the impingement location.