Producing cut surfaces in a transparent material by means of optical radiation
A method for producing a cut surface in a transparent material using optical radiation. A laser device separates the material using optical radiation and includes an optical unit focussing the radiation along an optical axis into an image field defining an image-field size. A focal position is adjusted transversely along the axis, producing a cut surface extending substantially parallel to the axis and, in projection along the axis, is a curve having a maximum extent. The focus is displaced by adjustment of the focal position along a trajectory curve lying in the cut surface. The cut surface has a maximum extent which is greater than the image-field size. The focal position is moved transverse to the axis along the curve. The image field is displaced transversely, and the focal position is adjusted in an oscillating fashion along the axis on the curve between an upper and lower axial focus position.
1. A method for producing a cut in a transparent material comprising eye tissue, the method comprising
focussing optical radiation into the transparent material by using optics which define an optical axis and have in the material an image field of an image field size, and
generating the cut by shifting a focus within the material along an oscillating path which is located in the cut,
wherein generating the cut by shifting the focus within the material along the oscillating path comprises moving a position of the focus in a direction transverse to the optical axis, and during such transverse movement, moving the position of the focus along the oscillating path between an upper axial focus position and a lower axial focus position, wherein the oscillating path comprises upward sections in which the position of the focus moves along the oscillating path against a direction of incidence of the optical radiation with the material, and from the lower axial focus position to the upper axial focus position and downward sections in which the position of the focus moves along the oscillating path with the direction of incidence of the optical radiation with the material, and from the upper axial focus position to the lower axial focus position,
wherein each of the upward sections is asymmetrical to a subsequent and adjacent downward section with respect to an axis which is parallel to the optical axis and runs through a turning point connecting the upward section and the subsequent and adjacent downward section, and
wherein each of the downward sections is asymmetrical to a subsequent and adjacent upward section with respect to an axis which is parallel to the optical axis and runs through a turning point connecting the downward section and the subsequent and adjacent upward section.
2. The method according to claim 1 , further comprising switching the optical radiation off while shifting the focus within the oscillating path along a downward section, or modifying the optical radiation while shifting the focus within the oscillating path along the downward section, such that the optical radiation has no material-cutting effect in the material on the downward section.
3. The method according to claim 1 , wherein the downward sections each form an acute angle with the axis which is parallel to the optical axis and runs through a turning point connecting the downward section and a subsequent and adjacent upward section that is less than an acute angle formed between the subsequent and adjacent upward section and the axis which is parallel to the optical axis and runs through the turning point connecting the downward section and the subsequent and adjacent upward section.
4. The method according to claim 3 , wherein the cut has a shape of a cylinder surface.
5. The method according to claim 1 , wherein the upper axial focus position defines an upper edge of the cut and the lower axial focus position defines a lower edge of the cut.
6. The method according to claim 1 , further comprising moving the position of the focus in the direction transverse to the optical axis while shifting the image field in a direction transverse to the optical axis, and wherein generating the cut further comprises generating the cut so that the cut has a maximum extent transverse to the optical axis which maximum extent exceeds the image field size.
7. The method according to claim 6 , wherein shifting the image field transverse to the optical axis comprises displacing at least a part of the optics transverse to the optical axis.
8. The method according to claim 3 , wherein the cut extends substantially parallel to the optical axis and defines, in projection along the optical axis, a form of a curve and the curve is a periodic Lissajous figure.
9. The method according to claim 3 , wherein the cut extends substantially parallel to the optical axis and defines, in projection along the optical axis, a form of a curve and the curve is a closed curve.
10. The method according to claim 1 , wherein the upper axial positions are laterally offset against subsequent lower axial positions and vice versa.
11. The method according to claim 10 , wherein the cut is inclined to the optical axis.