Can you measure background or RTC with a thermocouple?

• A. Yes
• B. No
• C. Only if the thermocouple is a special type
• D. Only at high temperatures

Answer: (B)

A thermocouple measures temperature at a contact point; it does not detect radiant energy. The background or RTC (reflected temperature component) is part of the radiance that reaches an infrared camera due to surroundings and reflections, not the temperature at a junction you touch with a probe. Because a thermocouple reads conduction temperature, not radiation, it cannot directly measure this radiometric background. To account for RTC you’d use radiometric sensors (like an IR camera or a dedicated radiometer) or, at best, estimate ambient temperature with a separate sensor—not a thermocouple serving as a radiance detector. Hence the best answer is that you cannot measure background or RTC with a thermocouple.