An Imaging System to Study Spin Dynamics in Ultracold Sodium Gases

Abstract

Optical imaging plays a central role in ultracold atom experiments by enabling quantitative measurements of atomic density, temperature, atom number, and condensate dynamics. Achieving high-fidelity absorption imaging requires a well-characterized optical system with accurately calibrated magnification and spatial resolution. In this work, I designed, implemented, and experimentally characterized a dual-view optical imaging platform for future absorption imaging of ultracold sodium atoms. The system consists of two independent three-lens relay imaging systems providing top and side views of the atomic sample. Two low-magnification configurations with nominal magnification 0.6 were developed for imaging the relatively large sodium magneto-optical trap (MOT), while higher-magnification configurations with nominal magnifications of 4 and 10 were designed for Bose–Einstein condensate (BEC) imaging. The work included the integration and optimization of the laser cooling and trapping apparatus, improvements to the magnetic-field control system, and the alignment and calibration of both imaging paths. Characterization using a laser and a USAF 1951 resolution target yielded measured magnifications of 0.653 ± 0.033 and 0.521 ± 0.016 for the side and top MOT imaging systems, with corresponding spatial resolutions of 13.92 µm and 9.84 µm. The BEC imaging systems achieved measured magnifications of 4.094 ± 0.060 (top) and 10.817 ± 0.172 (side), with spatial resolutions of 9.84 µm and 6.20 µm, respectively. These measurements agree well with the theoretical diffraction-limited resolutions of 7.19 µm for the 0.6 and 4 magnification systems and 2.87 µm for the 10 magnification system, with the remaining differences attributed primarily to practical optical aberrations and alignment tolerances. The calibrated dual-view imaging platform provides the spatial resolution and quantitative accuracy required for absorption imaging of ultracold sodium atoms and establishes the experimental foundation for future investigations of sodium magneto-optical traps, Bose–Einstein condensation, and coherent spin dynamics in spinor sodium gases.