Abstract: An isolated signal probe comprises an input module, an output module, and a fiber optic line connecting the input module to the output module. The input module includes external positive and negative terminals, an input translation circuit electrically connected to the external positive and negative terminals, a first power supply for driving the input translation circuit, and an electrical-to-optical converter that receives a first signal from the input translation circuit. The output module includes an optical-to-electrical converter, an output translation circuit for receiving a second signal from the optical-to-electrical converter; a second power source for driving the output translation circuit, and an output connector electrically connected to the output translation circuit. The fiber optic line connects the electrical-to-optical converter to the optical-to-electrical converter.