A STEM outreach tool for demonstrating the sensing and compensation of atmospheric turbulence

Abstract

The US Air Force (USAF) conducts research involving the sensing and compensation of atmospheric turbulence, which acts to blur images and make laser-beam propagation more challenging. As such, USAF scientists and engineers (S&Es) often face the challenging task of explaining this research to audiences without relevant technical expertise. These audiences vary widely all the way from upper military leadership down to K-12 students as part of science, technology, engineering, and mathematics (STEM) outreach activities. Previously, a team of USAF S&Es developed a table-top setup for the demonstration of digital-holography (DH) technology. This technology enables the measurement of the complex-optical field, which in turn enables a plethora of applications that involve imaging and wavefront sensing. Therefore, in this paper we extend this table-top setup to illustrate both the effects of atmospheric turbulence on the imaging and wavefront sensing process and the digital-signal processing required to estimate and mitigate these effects. The enhanced demonstration provides a visual-learning aid to help explain the complicated concepts associated with imaging through atmospheric turbulence. Specifically, we show that we can introduce aberrations into the DH system and use digital-image correction to refocus the resultant blurry images. This paper discusses the overall system design, improvements, and lessons learned.

Rotating target detection model under arbitrary incidence of the vortex beam based on optical RDE

“…According to equations (19) and (20), when e q equals to 0, i.e., the beam is vertically incident on the target,…”

“…where j D is the distorted phase by atmospheric turbulence [19][20][21]. Therefore, in the presence of atmospheric turbulence, a distortion term d dt 2 ( ) / / j p D will be added to the original frequency shift, which will widen the frequency spectrum.…”