Code formation method and information code

Abstract

A code formation method for forming an information code on a target object is provided. The information code stores information with an array of a light area and a dark area. The code formation method includes forming an emissive layer by applying, to the target object, a coating material containing a reactive paint that emits light in response to invisible light, and irradiating a portion of the emissive layer corresponding to the dark area with laser light to reduce an emissive performance of the dark area to be lower than an emissive performance of the light area. The irradiating with the laser light includes irradiating with the laser light to make a transmittance for the invisible light in the portion corresponding to the dark area higher than a transmittance for the invisible light in a portion of the emissive layer corresponding to the light area.