Patent ID: 7116412

Claim:
An angle detection optical system, comprising: a light source that irradiates light onto a reflective surface for detection provided on a detection object; an optical path splitting element that splits reflected light that has been reflected by the reflective surface for detection into first and second luminous fluxes that are respectively propagated on at least first and second optical paths that are different from each other; a first optical detector that is placed on the first optical path so as to receive the first luminous flux; and a second optical detector that is distanced from the first optical detector and placed on the second optical path so as to receive the second luminous flux; wherein a first amount of movement of the first luminous flux on a first light receiving surface of the first optical detector is different from a second amount of movement of the second luminous flux on a second light receiving surface of the second optical detector, and the first and second amount of movement are caused by a variation in the inclination angle of the detection object.