Method for laser machining inside materials

Abstract

The invention provides a method for laser modification of a sample to form a modified region at a target location within the sample. The method comprises positioning a sample in a laser system for modification by a laser; measuring tilt of a surface of the sample through which the laser focusses; using at least the measured tilt to determine a correction to be applied to an active optical element of the laser system; applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of coma on laser focus; and laser modifying the sample at the target location using the laser with the corrected wavefront properties to produce the modified region.

1 - 39 . (canceled) 
     
     
         40 . A sample comprising a plurality of spatially separated laser-modified regions, each having a size of less than 1 micrometre in at least one dimension. 
     
     
         41 . A sample as claimed in  claim 40 , comprising a structure formed by the plurality of laser-modified regions, wherein the structure is two dimensional or three dimensional. 
     
     
         42 . A sample as claimed in  claim 40 , comprising an optical volume formed by the plurality of spatially separated laser-modified regions. 
     
     
         43 . A sample as claimed in  claim 41 , comprising an optical volume formed by the plurality of spatially separated laser-modified regions. 
     
     
         44 . A sample as claimed in  claim 42 , wherein the optical volume comprises a visible feature. 
     
     
         45 . A sample as claimed in  claim 43 , wherein the optical volume comprises a visible feature. 
     
     
         46 . A sample as claimed in  claim 42 , wherein the optical volume is configured for detection by phase contrast microscopy or dark field microscopy. 
     
     
         47 . A sample as claimed in  claim 43 , wherein the optical volume is configured for detection by phase contrast microscopy or dark field microscopy. 
     
     
         48 . A sample as claimed in  claim 40 , comprising a predetermined stress field generated by the plurality of spatially separated laser-modified regions. 
     
     
         49 . A sample as claimed in  claim 48 , wherein each of the plurality of spatially separated laser-modified regions is configured to generate a respective stress load on the surrounding sample that is different from that of at least one other of the plurality of laser-modified regions. 
     
     
         50 . A sample as claimed in  claim 40 , wherein the sample is a crystal lattice. 
     
     
         51 . A sample as claimed in  claim 40 , wherein the sample bulk is diamond. 
     
     
         52 . A sample as claimed in  claim 40 , wherein the plurality of laser-modified regions form electrical conductors. 
     
     
         53 . A sample as claimed in  claim 41 , wherein the plurality of laser-modified regions form electrical conductors. 
     
     
         54 . A sample as claimed in  claim 40 , wherein the plurality of laser-modified regions comprises a security code. 
     
     
         55 . A sample as claimed in  claim 40 , wherein the plurality of laser-modified regions comprises a diffraction grating. 
     
     
         56 . A sample as claimed in  claim 40 , wherein the plurality of laser-modified regions form one of an alphanumeric character, a barcode, a quick response (QR) code, an image, a diffractive element, or a hologram. 
     
     
         57 . A sample as claimed in  claim 40 , wherein each of the plurality of laser-modified regions is less than 1 micrometre in all dimensions. 
     
     
         58 . A sample as claimed in  claim 40 , wherein each of the plurality of laser-modified regions is more than 100 micrometres below the nearest surface of the sample.