Optical assembly to modify numerical aperture of a laser beam

An optical assembly to process laser light output from a laser source, the optical assembly comprising:

• a housing to receive a distal end of an optical fiber that outputs the laser light;
• one or more beam traps contained within the housing or coupled to the housing, the one or more beam traps configured to receive laser light and convert the received laser light to heat;
• means for removing the heat from the housing, the heat removal means thermally coupled to the one or more beam traps;
• and
• one or more optical apertures located inside the housing, at least one of the optical apertures to define a numerical aperture (NA) of a first portion of the laser light based on a radial dimension of the at least one optical aperture, the at least one optical aperture arranged to pass the first portion of the light and redirect a second different portion of the laser light to the one or more beam traps,
• wherein the laser light received by the one or more beam traps for conversion to heat comprises the redirected second different portion of the laser light.