A Robust, Diffraction-limited Objective Lens Design Utilizing COTS Components for AMO Experiments*

We present a robust imaging system optimized for atomic, molecular, and optical physics experiments. Our design utilizes readily available commercial off-the-shelf (COTS) components to construct an objective lens that corrects for spherical aberrations and efficiently collects atomic fluorescence. Unlike traditional designs that require separate collimation and refocusing stages, our objective directly converges light to the back focal plane with a single lens group. This simplified configuration achieves high photon transmission and diffraction-limited performance across a wide range of wavelengths with adjustable objective length providing substantial flexibility to accommodate experiments with mechanical constraints. Our example objective has a long front working distance of 61 mm and a high numerical aperture (NA) of 0.3, limited by an aperture in the experimental setup (the full objective NA is 0.4). We experimentally verify that the design achieves diffraction-limited resolution at wavelengths from 375 nm to 866 nm. Specifically, when imaging 397 nm light (i.e. from 40Ca+ ion fluorescence), the objective reaches a resolution of 0.87 μm with a 540 μm field of view. Furthermore, the design maintains this performance over a 5 cm range variation of both front and back working distances. Additionally, we develop a method to qualitatively measure the field of view using a calibrated target. This robust, cost-effective, and versatile design is ideal for various AMO experiments, enabling the exploration of diverse quantum phenomena and high-precision measurements.