  A multispeckle technique for efficiently measuring correctly
ensemble-averaged intensity autocorrelation functions of scattered light from
non-ergodic and/or non-stationary systems is described.
  The method employs a CCD camera as a multispeckle light detector and a
computer-based correlator, and permits the simultaneous calculation of up to
500 correlation functions, where each correlation function is started at a
different time.
  The correlation functions are calculated in real time and are referenced to a
unique starting time.
  The multispeckle nature of the CCD camera detector means that a true ensemble
average is calculated; no time averaging is necessary.
  The technique thus provides a "snapshot" of the dynamics, making it
particularly useful for non-stationary systems where the dynamics are changing
with time.
  Delay times spanning the range from 1 ms to 1000 s are readily achieved with
this method.
  The technique is demonstrated in the multiple scattering limit where
diffusing-wave spectroscopy theory applies.
  The technique can also be combined with a recently-developed two-cell
technique that can measure faster decay times.
  The combined technique can measure delay times from 10 ns to 1000 s.
  The method is peculiarly well suited for studying aging processes in soft
glassy materials, which exhibit both short and long relaxation times,
non-ergodic dynamics, and slowly-evolving transient behavior.
