Data-acquisition system for temperature measurement in the state primary standard for the length unit

The state primary standard for the length unit can be improved by an automated system for measuring the temperature in the working space. For example, in interference measurements with length standards, the accurate determination of the deviation in the mean volume temperature of the measure from 20°C governs the accuracy in determining the length. A modern interference comparator employs differential thermoelectric thermometers to determine the temperature gradients together with a standard platinum resistance thermometer for determining the measure's temperature. A data-acquisition system DAS for precision temperature measurement on the basis of a microcomputer has been designed, built and tested.