How does a two color pyrometer handle emissivity variation in materials?

A two color pyrometer handles emissivity variations in materials by measuring the ratio of radiation intensities at two different wavelengths. Unlike single-color pyrometers, it doesn't rely on a fixed emissivity value, making it less sensitive to changes in a material's surface properties. This ratio-based approach allows the two color pyrometer to provide accurate temperature readings even when emissivity varies, ensuring reliable measurements in challenging conditions, such as high-temperature environments or when dealing with materials with fluctuating surface characteristics.