Subwavelength-grating-induced wavefront aberrations: a case study

摘要

The on-axis wavefront aberrations of a one-dimensional subwavelength-grating antireflection coating onan f/1.7 lens surface are shown to be small with noticeable contributions of defocus, astigmatism, and piston. The astigmatism is 0.02 wave, and the magnitude of the piston approaches one wave peak-to-valley. The difference in aberrations between orthogonally polarized wavefronts, or the retardance aberration, shows 0.01 wave of astigmatismlike variation and more than 0.01 wave of retardance-induced defocuslike variation. A small coupling between polarization states occurs in the form of the familiar Maltese cross, yielding a maximum of 3percent coupling in the four diagonal edges of the pupil.