Light source device, method of manufacturing light source device, and line head module

A method of manufacturing a light source device including a light-emitting unit having a plurality of light-emitting elements, a first optical unit that substantially collimates beams emitted from the light-emitting elements in a first direction, and a second optical unit that condenses the emitted beams substantially collimated by the first optical unit in a second direction intersecting the first direction, the light-emitting unit being arranged such that the plurality of light-emitting elements are aligned in the first direction, and the first optical unit including a beam-condensing element group having a plurality of beam-condensing elements disposed near to every light-emitting element, the method comprising:

• measuring the quantity of light of the light-emitting elements, and
• forming the beam-condensing element group so that a beam-condensing element group corresponding to one light-emitting element has a larger number of beam-condensing elements than a beam-condensing element group corresponding to other light-emitting elements each of which has a greater quantity of light than the one light-emitting element.