Laser system

An apparatus comprising:

• a mechanism reducing feature dimension roughness in an exposed photoresist layer exposed by a pulsed sub-400 nm light source comprising:
• a coherence busting mechanism comprising a coherence busting optical structure generating multiple sub-pulses delayed sequentially from a single input pulse, wherein each sub-pulse is delayed from the following sub-pulse by more than the coherence length of the light pulse.

An apparatus comprising:

• a mechanism reducing feature dimension roughness in an exposed photoresist layer exposed by a pulsed sub-400 nm light source comprising:
• a laser light source comprising a seed laser and an amplification gain stage;
• a coherence busting mechanism intermediate the seed laser and the amplification stage comprising a beam splitter separating the seed laser output into a main beam and a beam entering an optical delay path having a delay length longer than the coherence length of a pulse in the seed laser output.