Microlensing is generally thought to probe planetary systems only out to a few Einstein radii. Microlensing events generated by bound planets beyond about 10 Einstein radii generally do not yield any trace of their hosts, and so would be classified as free floating planets (FFPs). I show that it is already possible, using adaptive optics (AO), to constrain the presence of potential hosts to FFP candidates at separations comparable to the Oort Cloud. With next-generation telescopes, planets at Kuiper-Belt separations can be probed. Next generation telescopes will also permit routine vetting for all FFP candidates, simply by obtaining second epochs 4--8 years after the event.At present, the search for such hosts is restricted to within the ``confusion limit'' of θconfus ∼ 0.25 〃, but future WFIRST (Wide Field Infrared Survey Telescope) observations will allow one to probe beyond this confusion limit as well.

Abstract
1. INTRODUCTION
2. CONFUSION LIMIT OF MICROLENSING
3. OORT PLANETS FROM AO ON EXISTINGTELESCOPE
4. KUIPER PLANETS FROM AO ON NEXTGENERATION TELESCOPES
5. AO IMAGING OF ALL FFP CANDIDATES
6. PROBING KUIPER PLANETS WITH WFIRST
7. BEYOND THE CONFUSION LIMIT
8. DYNAMICAL STABILITY OF OORT PLANETS
9. CONCLUSION
REFERENCES

• Andrew Gould(Max-Planck-Institute for Astronomy/Korea Astronomy and Space Science Institute/Department of Astronomy, Ohio State University) Corresponding author