Exposure apparatus and image forming apparatus

An image forming apparatus comprising:

• a plurality of light sources each of which emits light;
• a photoreceptor that includes a photosensitive surface on which an image is drawn by receiving illumination of a light and in which at least the photosensitive surface moves in a first direction along the photosensitive surface;
• a scanning optical system that guides each of the lights emitted from the plurality of light sources to the photosensitive surface included in the photoreceptor to scan the photosensitive surface in a second direction crossing the first direction by each of the lights and that guides a plurality of lights whose light sources are different from one another to positions different from one another in the first direction on the photosensitive surface;
• a light concentrating section that concentrates the lights which are emitted from the plurality of light sources and which are guided to the photosensitive surface by the scanning optical system, on the photosensitive surface, and that also has a function to adjust a light concentrating position to a light traveling direction;
• a light receiving device to which a plurality of lights whose light sources are different from one another are guided and emitted from a part of a movement range of light that moves along with scanning by the scanning optical system so as to receive separately the plurality of lights, which includes a plurality of light receiving parts to detect a received light quantity of each of the lights, and in which an optical path length to the light receiving part is greater than the optical path length to the photosensitive surface as for a part of the plurality of lights that pass through on the plurality of light receiving parts along with the scanning, and the optical path length to the light receiving part is smaller than the optical path length to the photosensitive surface as for another part of the plurality of lights;
• and
• a light concentrating position adjusting section that uses the function of the light concentrating section to adjust the light concentrating position by the light concentrating section based on the received light quantity detected by each of the plurality of light receiving parts included in the light receiving device;
• and
• a transferring and fixing section that transfers and fixes the toner image formed by the toner image forming section to a recording medium.