  The FCAL collaboration is preparing large-scale prototypes of special
calorimeters to be used in the very forward region at future electron-positron
colliders for a precise measurement of integrated luminosity and for instant
luminosity measurement and assisting beam-tuning. LumiCal is designed as a
silicon-tungsten sandwich calorimeter with very thin sensor planes to keep the
Moli\`ere radius small, facilitating such the measurement of electron showers
in the presence of background. Dedicated front-end electronics has been
developed to match the timing and dynamic range requirements. A partially
instrumented prototype was investigated in a 1 to 5 GeV electron beam at the
DESY II synchrotron. In the recent beam tests, a multi-plane compact prototype
was equipped with thin detector planes fully assembled with readout electronics
and installed in 1 mm gaps between tungsten plates of one radiation length
thickness. High statistics data were used to perform sensor alignment, and to
measure the longitudinal and transversal shower development in the sandwich.
This talk covers the latest status of the calorimeter prototype development and
selected performance results, obtained in test beam measurements, the prospects
for the upcoming DESY test beam, as well as the expected simulation
performance.
