Abstract
In this work we present a comprehensive review of recent work carried out by our group in the field of optical refrigeration of Nd-doped solids. Several infrared thermography measurements in Nd-doped KPb2Cl5 crystals and micro-powders both above and below the barycentre of the F-4(3/2) are presented. These include some of our most recent ones obtained by employing a novel technique that allows one to perform differential temperature measurements. The role of both the direct anti-Stokes absorption processes and those assisted by either excited state absorption or energy transfer upconversion in the cooling process is discussed.