  We report on a novel device capable of imaging second-order spatio-temporal
correlations g2(x,t) between photons. The imager is based on a monolithic array
of single-photon avalanche diodes (SPAD) implemented in CMOS technology and a
simple algorithm to treat multiphoton time-of-arrival distributions from
different SPAD pairs. It is capable of 80 ps temporal resolution with fluxes as
low as 10 photons/s at room temperature. An important application might be the
local imaging of g2 as a means of confirming the presence of true Bose-Einstein
macroscopic coherence (BEC) of cavity exciton polaritons.
