Laser scanning unit, image forming apparatus, laser scanning method, and non-transitory storage medium

A laser scanning method comprising:

• outputting a plurality of light beams from a light source portion;
• scanning the plurality of light beams to form a plurality of electrostatic latent images, respectively corresponding to a plurality of colors including at least one reference color and at least one non-reference color, in an image forming portion;
• applying an external mechanical force to an optical element located in a path of a reference beam, corresponding to the reference color, among the plurality of light beams to correct distortion of a scan line of the reference beam;
• and
• controlling the light source portion to correct distortion of a scan line of a non-reference beam, corresponding to the non-reference color, among the plurality of light beams.

A non-transitory computer-readable storage medium storing a program therein, wherein when executed by at least one processor, the program causes the processor to:

• output a plurality of light beams from a light source portion;
• scan the plurality of light beams to form a plurality of electrostatic latent images, respectively corresponding to a plurality of colors including at least one reference color and at least one non-reference color, in an image forming portion;
• apply an external mechanical force to an optical element located in a path of a reference beam, corresponding to the reference color, among the plurality of light beams to correct distortion of a scan line of the reference beam;
• and
• control the light source portion to correct distortion of a scan line of a non-reference beam, corresponding to the non-reference color, among the plurality of light beams.