Differential thermometer for high temperature flow calorimetry

An AC platinum resistance thermometer bridge is the basis for a high resolution differential thermometer which has a resolution of better than 0.1 mK, an accuracy of better than +or-0.2 mK +or-0.1% of reading. The thermometer is designed to measure temperature differences of up to +or-3 K over the operating range of 0 to 600 degrees C. The thermometer uses a true four-lead resistance measurement and includes a novel facility to check for self-heating errors.