DIFFRACTIVE LENS

摘要

The disclosed diffractive lens has a light-focusing effect, and has a surface with a diffraction grating along a aspherical or spherical surface in the effective region. The diffraction grating has n0 concentric circular phase steps centered on the optical axis of the diffraction lens, and, counting from the optical axis of the diffraction lens, the radius rn of the circle formed by the nth (n being an integer between 0 and n0) phase step fulfils the expression below. a, b, c, and m are constants with a > 0, 0 ? c n is any value between -0.25 n < 0.25.