Salvatore Buontempo presented this interesting technique at the Italian Society of Physics.
Because of its potential utility for KAGRA environmental and facility (including cryogencs) monitoring, I upload it to make it available to the KAGRA community.
Vincenzo Galdi (Unisannio and KAGRA) is presently evaluating the possibility of adapting it for use in KAGRA and transferring the technology to KAGRA.
Our thanks to Salvatore for making this file and the technology available to KAGRA if desired.