Thermal imaging does not radiate waves of any type. It is not a hazard to people or pets. It does not allow the operator to see through walls or other materials.
Thermal imaging allows the technician to find otherwise hidden deficiencies.
The left picture shows a dining room ceiling. Everything looks normal to the naked eye. The dark blue areas in the right picture show areas of moisture coming from a hidden plumbing leak on the second floor.
These pictures are from a new construction inspection. The left picture shows the master bedroom ceiling. The light colored areas in the right picture show where insulation was not installed. The energy loss and the inability to properly control the temperature would have plagued the homeowners for as long as they lived in the home.