Susceptibility to and correction of azimuthal aberrations in singular light beams

TL;DR

This paper investigates how azimuthal aberrations affect singular light beams, causing intensity distortions that can be measured and corrected using a feedback loop with a spatial light modulator.

Contribution

It demonstrates a method to measure and correct azimuthal aberrations in singular light beams using a programmable spatial light modulator and intensity feedback.

Findings

Azimuthal aberrations cause intensity modulations proportional to aberration amplitude.

The pattern of intensity modulation relates to the azimuthal order of aberration.

A closed-loop correction system effectively reduces aberrations in singular light beams.

Abstract

We show how the effects of azimuthal optical aberrations on singular light beams can result in an intensity modulation in the beam waist or focal point spread function (PSF) that is directly proportional to the amplitude of the applied phase aberration. The resulting distortions are enough to significantly degrade the utility of the singular beams even in well corrected optical systems. However we show that pattern of these intensity modulations is related to the azimuthal order of the applied aberration and we suggest how this can be used to measure those aberrations. We demonstrate a closed loop system using a liquid crystal spatial light modulator as a programmable diffractive optical element to both generate the beam and correct for the sensed aberrations based on feedback from a CCD detected intensity image of the focal point spread function.