US Patent 9477018 Diffractive optical element and measurement device

Disclosed are a diffractive optical element and a measurement device that are capable of reliably suppressing occurrence of a zero-order diffracted light beam and generating light spots in a wide range. The diffractive optical element has concave and convex portions and diffracts incident light in two dimensions to generate diffracted light. When a maximum diffraction angle with reference to an optical axis of the incident light is an angle range θ, the angle range θ is 7.5° or greater, and diffraction efficiency in a zero-order diffracted light beam is 5% or less.