  The VERITAS Imaging Air Cherenkov Telescope array (IACT) was augmented in
2019 with high-speed focal plane electronics to allow the use of VERITAS for
Stellar Intensity Interferometry (SII) observations. Since that time, several
improvements have been implemented to increase the sensitivity of the VERITAS
Stellar Intensity Interferometer (VSII) and increase the speed of nightly data
processing. This poster will describe the use of IACT arrays for performing
ultra-high resolution (sub-milliarcsecond) astronomical observations at short
visible wavelengths. The poster presentation will include a description of the
VERITAS-SII focal plane, data acquisition, and data analysis systems. The
poster concludes with a description of plans for future upgrades of the VSII
instrument.
