Optical angle sensor

An optical angle comprising:

• a diffraction unit having a diffraction grating disposed at a predetermined period along the measurement direction;
• a light source for irradiating light toward the diffraction unit;
• a light receiving unit for receiving light through the diffraction unit;
• a calculating unit for calculating the amount of change in the angle of measurement target which rotates around a predetermined axis as a rotation axis based on the light received by the light receiving unit;
• and
• a plurality of reflection units that are irradiated by the light source and reflect light through the diffraction unit toward the diffraction unit,
• wherein the diffraction unit is attached to the measurement target, and rotates in synchronization with the rotation of the measurement target, and
• the diffraction unit comprises:
• a first diffraction part that divides and diffracts the light from the light source into first light and second light different from the first light, and diffracts and combines the first light and the second light through the plurality of reflection units into a combined light to be received by the light receiving unit;
• and
• a second diffraction part that diffracts and emits the first light and the second light through the plurality of reflection units to the plurality of reflection units, and diffracts and emits the first light and the second light reflected by the plurality of reflection units that are incident in the opposite direction to the case of emission to the plurality of reflection units,
• the plurality of reflection units comprises:
• a first reflection unit for reflecting the first light divided and diffracted by the first diffraction part toward the second diffraction part in a direction parallel to and opposite to the direction in which the first light is incident;
• a second reflection unit for reflecting the second light divided and diffracted by the first diffraction part toward the second diffraction part in a direction parallel to and opposite to the direction in which the second light is incident;
• a third reflection unit for reflecting the first light and the second light through the second part unit toward the second diffraction part;
• a fourth reflection unit for reflecting the first light diffracted by the second diffraction part toward the first diffraction part in a direction parallel to and opposite to the direction in which the first light is incident;
• and
• a fifth reflection unit for reflecting the second light diffracted by the second diffraction part toward the first diffraction part in a direction parallel to and opposite to the direction in which the second light is incident,
• the receiving unit includes a light receiving surface to which the combined light is irradiated, and
• the calculating unit, with the rotation of the diffraction unit, calculates the amount of change in the angle based on the change in the interference signal caused by the combined light generated on the light receiving surface.