A motorized rotation mount for fast and reproducible optical polarization control

TL;DR

This paper introduces a motorized rotation mount for half-wave plates that enables rapid, precise, and reproducible polarization control of light, suitable for ultracold atom experiments and other optical applications.

Contribution

A novel motorized rotation mount design using a hollow-shaft stepper motor for fast, accurate, and reproducible polarization switching with minimal mechanical complexity.

Findings

Switching time of 15.9 ms achieved

Reaction time of 0.52 ms demonstrated

Reproducibility confirmed over 2000 tests in 11 hours

Abstract

We present a simple motorised rotation mount for a half-wave plate that can be used to rapidly change the polarization of light. We use the device to switch a high power laser beam between different optical dipole traps in an ultracold atom experiment. The device uses a stepper motor with a hollow shaft, which allows a beam to propagate along the axis of the motor shaft, minimising inertia and mechanical complexity. A simple machined adapter is used to mount the wave plate. We characterise the performance of the device, focusing on its capability to switch a beam between the output ports of a polarizing beamsplitter cube. We demonstrate a switching time of 15.9(3) ms, limited by the torque of the motor. The mount has a reaction time of 0.52(3) ms, and a rotational resolution of 0.45 degrees. The rotation is highly reproducible, with the stepper motor not missing a step in 2000 repeated tests over 11 hours.