Flattening axial intensity oscillations of a diffracted Bessel beam through a cardioid-like hole

TL;DR

This paper introduces a novel cardioid-like hole design to stabilize the axial intensity of a diffracted Bessel beam, offering a practical and accurate method for applications like laser machining and optical trapping.

Contribution

The paper proposes a new hard truncation technique using a cardioid-like hole to suppress axial intensity oscillations in Bessel beams, improving upon previous methods.

Findings

Stable Bessel beam propagation over long distances after passing through the hole

Hard truncation outperforms gradual absorption in suppressing oscillations

Method is easier to implement and more accurate

Abstract

We present a new feasible way to flatten the axial intensity oscillations for diffraction of a finite-sized Bessel beam, through designing a cardioid-like hole. The boundary formula of the cardioid-like hole is given analytically. Numerical results by the complete Rayleigh-Sommerfeld method reveal that the Bessel beam propagates stably in a considerably long axial range, after passing through the cardioid-like hole. Compared with the gradually absorbing apodization technique in previous papers, in this paper a hard truncation of the incident Bessel beam is employed at the cardioid-like hole edges. The proposed hard apodization technique takes two advantages in suppressing the axial intensity oscillations, i.e., easier implementation and higher accuracy. It is expected to have practical applications in laser machining, light sectioning, or optical trapping.