Method of manufacturing print head, print head and image forming apparatus, using light density data for print head correction

A method of manufacturing a print head that includes a substrate on which a plurality of light-emitting units are provided to be arrayed, and a driver that drives each of the light-emitting units, wherein a light spot is formed on a field by each of the light-emitting units, comprising:

• a first step of finding first light quantity related data of a light quantity in the light spot formed by lighting up the light-emitting unit by the driver by using a first threshold;
• a second step of finding first magnitude related data of a magnitude in the light spot, formed by lighting up the light-emitting unit by the driver by using a second threshold;
• a third step of finding first ratio data of a ratio between the first light quantity related data and the first magnitude related data;
• and
• a fourth step of providing light quantity correction data to the light-emitting unit forming the light spot by using the first ratio data, and
• a fifth step of retaining the provided light quantity correction data at the print head, whereby the retained light quantity correction data may be used to correct a light quantity emitted by the light-emitting units.