This instrument measures temperatures beyond the range of ordinary thermometers and relies on the color produced by the object being heated:

The instrument that measures temperatures beyond the range of ordinary thermometers and uses the color produced by the heated object is a pyrometer. Pyrometers are specifically designed for high-temperature measurements and utilize the principles of thermal radiation. As an object is heated, it emits radiation in the form of light, and the color of that light changes with temperature—a phenomenon known as blackbody radiation. The pyrometer detects this emitted radiation and converts it into a temperature reading, allowing it to measure temperatures that are typically beyond the capabilities of standard thermometers.

The other instruments have different functions and are not designed for the same high-temperature applications. A thermocouple can measure a wide range of temperatures but does not rely on the visible color of the object. A bimetallic strip is primarily used for lower temperature measurements and operates based on the expansion of metals. A quartz ohmmeter is not relevant to temperature measurement at all; it is an instrument for measuring electrical resistance.