Optical sensor and image forming apparatus

An optical sensor, comprising:

• an irradiating system which irradiates, toward a surface of a subject a linearly polarized light in a first polarization direction from an incident direction which is slanted relative to a normal direction of the surface;
• a first photodetecting system including a first photodetector which is arranged on an optical path of a light which is specularly reflected from the subject;
• a second photodetecting system including an optical element which is arranged on an optical path of a light which is diffuse reflected from the subject within an incident face in the subject and which separates a linearly polarized component in a second polarizing direction which is orthogonal to the first polarization direction and a second photodetector which receives a light separated by the optical element;
• a restricting member which is arranged on an optical path of an incident light with respect to at least one photodetector amongst the first photodetector and the second photodetector and which restricts a light receiving range in the at least one photodetector;
• a third photodetecting system which includes at least one photodetector arranged on the optical path of the light which is diffuse reflected from the subject within the incident face in subject;
• and
• a processing unit which specifies the subject based on an output of the second photodetector and a ratio of an output of the first photodetector and the at least one photodetector of the third photodetecting system.

An optical sensor, comprising:

• an irradiating system which irradiates, toward a surface of a subject a linearly polarized light in a first polarization direction from an incident direction which is slanted relative to a normal direction of the surface;
• a first photodetecting system including a first photodetector which is arranged on an optical path of a light which is specularly reflected from the subject;
• a second photodetecting system including an optical element which is arranged on an optical path of a light which is diffuse reflected from the subject within an incident face in the subject and which separates a linearly polarized component in a second polarizing direction which is orthogonal to the first polarization direction and a second photodetector which receives a light separated by the optical element;
• a restricting member which is arranged on an optical path of an incident light with respect to at least one photodetector amongst the first photodetector and the second photodetector and which restricts a light receiving range in the at least one photodetector;
• a third photodetecting system which includes at least one photodetector arranged on the optical path of the light which is diffuse reflected from the subject within the incident face in the subject and at least one photodetector which receives a light which is transmitted through the at least one optical element;
• and
• a processing unit which specifies the subject based on an output of the first photodetector and a ratio of an output of the second photodetector and the at least one photodetector of the third photodetecting system.