The results of development of the series of Split-Stirling modular microcryogenic systems (MCSs) intended for use in the thermal image viewing and sighting devices of all fighting arms and commercial application are presented. The three structural variants of the MCSs are described. The developed MCSs allow cryostatting photo-sensitive cells (PSCs) of the different-type photo-detector divices (FDDs) on the temperature level of (75 to 80) K at the MCS heat load of 0,3 to 2,5 W. The 1 st class MCS is intended for use with heat loads of 0,8 to 2,5 W; the 2 nd class MCS - with those of 0,4 to 0,9 W and the 3 rd - for the rang of 0,3 to 0,5 W. The results of the MCS investigating and testing in different conditions are given.