Due to its short measuring wavelength the ratio pyrometer series optris CTratio is especially suited for measurement of high metal temperatures and the very short response time allows for surveillance of very fast processes. The ratio pyrometer is largely resistant against dust, steam and dirty observation windows. This allows for an accurate measurement in cases of window soiling of up to 90 percent. The pyrometer additionally measures reliably in cases where the measuring object only covers 5 percent of the measuring spot or moves very fast.

The rugged, electrically isolated sensing head and fiber optic cable makes the CTratio insensitive to electromagnetic fields and usable in ambient temperatures up to 315 °C without cooling.