Lens array, an exposure head and an image forming apparatus

An image forming apparatus, comprising:

• an exposure head that includes
• a light emitting element substrate that is provided with light emitting elements that emit lights and are arranged in a first direction and a second direction orthogonal or substantially orthogonal to the first direction,
• a lens array that has lenses that are arranged in the first direction and the second direction and image a light emitted from the light emitting elements, and
• a diaphragm that is arranged between the light emitting elements and the lenses;
• and
• a latent image carrier that is exposed by the exposure head to form a latent image and moves in the second direction,
• wherein a relationship defined by a following formula:
• 1<L1/L2
• is satisfied, where the symbol L1 denotes a length of the lens in the first direction and the symbol L2 denotes a length of the lens in the second direction.