Diffractive optical element and measurement instrument

摘要: A diffractive optical element includes: a first in which plurality of basic units are two-dimensionally arranged; and second arranged, wherein when direction the arranged is direction, an angle φ between such that −|φ 1 |<φ<|φ |, φ≠0, sin =−α/Δx where closest distance zero-order light generated diffracted by further incident on Δx stray α.