Diffractive optical element capable of being used for projecting oblique line, projection apparatus, and design method therefor

A projection apparatus, comprising:

• a light source configured to emit a light beam;
• a diffractive optical element, wherein the diffractive optical element is disposed downstream of the light source and receives the light beam, modulates the light beam and projects a pattern comprising an oblique line, an angle between the oblique line and a first direction is θ, the diffractive optical element comprising:
• a plurality of microstructure pattern units cyclically arranged in the first direction and a second direction, wherein the first direction is perpendicular to the second direction, a cycle of the microstructure pattern units in the first direction is d1, a cycle of the microstructure pattern units in the second direction is d2, and the first cycle d1 and the second cycle d2 are determined according to the angle,
• wherein a phase distribution map of the diffractive optical element is designed according to the first cycle d1, the second cycle d2 and a target pattern with an oblique line at 45°.