  We report on 25 sub-arcsecond binaries, detected for the first time by means
of lunar occultations in the near-infrared as part of a long-term program using
the ISAAC instrument at the ESO Very Large Telescope. The primaries have
magnitudes in the range K=3.8 to 10.4, and the companions in the range K=6.4 to
12.1. The magnitude differences have a median value of 2.8, with the largest
being 5.4. The projected separations are in the range 6 to 748 milliarcseconds
and with a median of 18 milliarcseconds, or about 3 times less than the
diffraction limit of the telescope. Among our binary detections are a pre-main
sequence star and an enigmatic Mira-like variable previously suspected to have
a companion. Additionally, we quote an accurate first-time near-IR detection of
a previously known wider binary.
  We discuss our findings on an individual basis as far as made possible by the
available literature, and we examine them from a statistical point of view. We
derive a typical frequency of binarity among field stars of ~10%, in the
resolution and sensitivity range afforded by the technique (~0.003" to ~0.5",
and K~12mag, respectively). This is in line with previous results by the same
technique but we point out interesting differences that we can trace up to
sensitivity, time sampling, and average distance of the targets. Finally, we
discuss the prospects for further follow-up studies.

Solar and Stellar Astrophysics;Instrumentation and Methods for Astrophysics