Laser processing device having an optical arrangement which comprises a beam splitter

A laser processing device comprising:

• an optical arrangement;
• wherein the optical arrangement comprises an input for receiving a laser beam;
• wherein the optical arrangement comprises a beam splitter that splits the laser beam into at least two partial beams;
• wherein the optical arrangement recombines the partial beams into a laser spot for generating an interference pattern in the laser spot;
• wherein a first state of the laser beam at the input generates a first interference pattern and a second state of the laser beam generates a second interference pattern;
• wherein the first state and the second state differ in at least one of (i) a position of the laser beam at the input and (ii) an angle of incidence of the laser beam with respect to the input;
• wherein a center of the first interference pattern and a center of the second interference pattern have a distance which corresponds to at least a single diameter of the laser spot, in particular at least five times the diameter of the laser spot, further in particular at least ten times the diameter of the laser spot;
• wherein a change in a path length of a radiation path of each of the partial beams due to the change in state from the first state to the second state is less than ±5% of the total path length of the radiation path from the beam splitter to the laser spot, in particular less than ±1% and further in particular less than ±0.5%.

An object having a surface comprising a periodic surface structure, wherein the surface structure defines a circumferential line which is an envelope of the surface structure, and wherein the circumferential line has, at least in sections in a circumferential line portion, a shape which is a periodic repetition of a basic element and wherein a periodicity of the surface structure is different from a periodicity of the circumferential line portion;

• wherein the circumferential line is defined by overlapping processing spots, wherein the processing spots comprise a first processing spot and a second processing spot;
• wherein the surface structure has a plurality of parallel trenches;
• wherein the surface structure comprises a first portion in the first processing spot and a second portion in the second processing spot and wherein the second portion of the surface structure continues the first portion of the surface structure in phase;
• wherein a first distance between a center of the first processing spot and a trench closest in a predetermined direction is different from a second distance between a center of the second processing spot and a trench closest in the predetermined direction.

An object having a surface, wherein

• the surface has a surface structure;
• the surface structure has a maximum extent in depth with respect to the surface;
• an extent in depth of the surface structure increases to 80% of the maximum extent in depth from a first position at an edge of the surface structure to a second position;
• and
• a distance between the first position and the second position is at least 100 μm.