  We have realized optical excitation, trapping and detection of the
radioisotope $^{81}$Kr with an isotopic abundance of 0.9 ppt. The 124 nm light
needed for the production of metastable atoms is generated by a resonant
discharge lamp. Photon transport through the optically thick krypton gas inside
the lamp is simulated and optimized to enhance both brightness and resonance.
We achieve a state-of-the-art $^{81}$Kr loading rate of 1800 atoms/h, which can
be further scaled up by adding more lamps. The all-optical approach overcomes
the limitations on precision and sample size of radiokrypton dating, enabling
new applications in the earth sciences, particularly for dating of polar ice
cores.
