Optical sensor and image forming apparatus

An optical sensor, comprising:

• a light emission system configured to emit an irradiated light of a linear polarization in a first polarization direction toward a surface of a target object having a sheet shape from an incident direction which is inclined with respect to a normal direction of the surface;
• a light detection system configured to include a light detector arranged on a light path of a diffuse reflected light which is diffusely reflected from an incident plane on the target object, the light detector receiving light passed by an optical element which passes a linear polarization component of a second polarization direction perpendicular to the first polarization direction;
• and
• an additional detection system configured to include an additional light detector arranged on a light path of a different diffuse reflected light which is diffusely reflected from the incident plane on the target object without passing the optical element,
• wherein the light detection system and the additional detection system are arranged on paths different from a light path of the specular reflected light which is emitted from the light emission system and is specularly reflected from the target object.