Billion km coherent telescopes: using the ISM lenses for pico-arcsecond measurements of pulsar properties.

Abstract: We present a new technique ‘VLBI scintillometry’ which uses VLBI to resolve the interstellar plasma lenses and then in turn uses these billion km lenses to achieve unprecedented imaging resolution of pulsar emission, and potentially measures pulsar distances and orbital properties.  New low frequency VLBI networks are emerging, combining the recently commissioned of low frequency telescopes across the earth.  I summarize recent developments, and upcoming prospects ranging from gravitational wave detection to pulsar mass, size, and emission region mapping.  I end with a physical proposal for the interstellar structures which give rise to plasma lenses.