Direct imaging of a digital-micromirror device for configurable microscopic optical potentials

TLDR

Programmable spatial light modulators have advanced configurable optical trapping, yet they are usually used in the Fourier plane, whereas direct imaging of amplitude patterns could simplify setups and speed computation. This work demonstrates high‑resolution direct imaging of a digital micromirror device at high numerical apertures for trapping a Bose‑Einstein condensate, enabling diverse optical potentials for superfluid dynamics and atomtronics. The authors employ a 1200×1920‑pixel DMD with 0.45‑NA objectives to pattern blue‑detuned 532‑nm light at 630‑nm FWHM resolution, and use time‑averaged potentials at 20‑kHz switching to create multiple grayscale levels with minimal heating. The system achieves near‑arbitrary control of BEC density without custom optics and offers broader applicability for optical trapping at non‑trivial numerical apertures.

Abstract

Programable spatial light modulators (SLMs) have significantly advanced the configurable optical trapping of particles. Typically, these devices are utilized in the Fourier plane of an optical system, but direct imaging of an amplitude pattern can potentially result in increased simplicity and computational speed. Here we demonstrate high-resolution direct imaging of a digital micromirror device (DMD) at high numerical apertures (NA), which we apply to the optical trapping of a Bose-Einstein condensate (BEC). We utilise a (1200 x 1920) pixel DMD and commercially available 0.45 NA microscope objectives, finding that atoms confined in a hybrid optical/magnetic or all-optical potential can be patterned using repulsive blue-detuned (532 nm) light with 630(10) nm full-width at half-maximum (FWHM) resolution, within 5% of the diffraction limit. The result is near arbitrary control of the density the BEC without the need for expensive custom optics. We also introduce the technique of time-averaged DMD potentials, demonstrating the ability to produce multiple grayscale levels with minimal heating of the atomic cloud, by utilising the high switching speed (20 kHz maximum) of the DMD. These techniques will enable the realization and control of diverse optical potentials for superfluid dynamics and atomtronics applications with quantum gases. The performance of this system in a direct imaging configuration has wider application for optical trapping at non-trivial NAs.