In-fiber beam shaping with short-focal-length lenses

An optical beam delivery system, comprising:

• a source fiber configured to provide an input beam having an input transverse spatial intensity distribution;
• and
• an image relay fiber assembly, comprising:
• a first lens configured to convert the input transverse spatial intensity distribution of the input beam to an intermediate beam having a divergence distribution;
• a divergence-preserving fiber to receive the intermediate beam and preserve its divergence distribution along a length of the divergence-preserving fiber;
• and
• a second lens configured to receive the intermediate beam from the divergence-preserving fiber and to provide an output beam as an image of the input beam.

A method of relaying an input beam from a laser source, the input beam having an input transverse spatial intensity distribution, the method comprising:

• directing the input beam to a first lens that is configured to map the input transverse spatial intensity distribution to a divergence distribution of an intermediate beam;
• guiding with a divergence-preserving fiber the intermediate beam while preserving its divergence distribution along a length of the divergence-preserving fiber;
• and
• directing the intermediate beam to a second lens configured to map the divergence distribution into an output transverse spatial intensity distribution so as to provide an output beam as an image of the input beam.