Diffractive optical element and measurement device

摘要

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.

主权项

1. A diffractive optical element, comprising:
a transparent substrate having a concave and convex pattern comprising concave portions and convex portions such that the concave and convex pattern diffracts incident light in two dimensions and generates diffracted light having a maximum diffraction angle with reference to an optical axis of an incident light in an angle range of 7.5° or greater, and diffraction efficiency of 5% or less in a zero-order diffracted light beam, wherein the concave and convex pattern has a distribution of the convex portions such that the convex portions have different shapes having different lengths measured in an X axis direction and a Y axis direction with respect to a Z axis direction representing a height direction of the convex and concave portions, and the lengths measured in the X axis and the Y axis are distributed in different frequencies within a range of λ/8 to 6λ where λ represents a wavelength of the incident light.