Gopinath's group develops photonic tools for sensing and imaging - electrowetting adaptive-optics and miniature two-photon/STED microscopes for in vivo neural imaging, dual-comb ranging and orbital-angular-momentum rotation sensing, and mid-infrared lasers/materials and fiber sensing. For context, this complements the established paradigm of NV-diamond ensemble magnetometry (Hahn-echo/DEER, nanoscale NMR, T1 relaxometry) operating near pT/√Hz sensitivity.