Lens unit, exposure device, reading head, image forming apparatus, and image reading apparatus

A lens unit comprising:

• a first lens array including a plurality of first lens elements each of which has a first optical axis, the first lens elements being arranged in an arrangement direction perpendicular to the first optical axis;
• and
• a second lens array including a plurality of second lens elements facing the first lens elements, each of the second lens elements having a second optical axis, the second lens elements being arranged in the arrangement direction, and
• a light shielding member disposed between the first lens array and the second lens array, the light shielding member including a plurality of openings arranged in the arrangement direction,
• wherein the second lens array is in a positional relationship relative to the first lens array such that the second lens array is rotated about a virtual line perpendicular to both the first optical axis and the arrangement direction as a rotational axis by 180 degrees,
• wherein the first optical axis of the first lens element located at a substantially center of the first lens array in the arrangement direction and the second optical axis of the second lens element located at a substantially center of the second lens array in the arrangement direction are arranged to substantially coincide with each other,
• wherein the first lens array includes a first positioning portion located at the substantially center in the arrangement direction, and the second lens array includes a second positioning portion located at the substantially center in the arrangement direction,
• wherein the light shielding member includes a first fitting portion into which the first positioning portion is fitted and a second fitting portion into which the second positioning portion is fitted, and
• wherein the first positioning portion and the second positioning portion are respectively fitted into the first fitting portion and the second fitting portion so that the first positioning portion and the second positioning portion face each other in a direction of the first optical axis via the light shielding member.